README.md

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-# math-learing
-

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.personalproject</groupId>
+    <artifactId>math-learning</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <name>Math Learning Application</name>
+    <description>A desktop application for math learning with exam functionality</description>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <javafx.version>21</javafx.version>
+        <javafx.maven.plugin.version>0.0.8</javafx.maven.plugin.version>
+    </properties>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>org.openjfx</groupId>
+            <artifactId>javafx-controls</artifactId>
+            <version>${javafx.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjfx</groupId>
+            <artifactId>javafx-fxml</artifactId>
+            <version>${javafx.version}</version>
+        </dependency>
+
+        <!-- Jakarta Mail for SMTP -->
+        <dependency>
+            <groupId>com.sun.mail</groupId>
+            <artifactId>jakarta.mail</artifactId>
+            <version>2.0.1</version>
+        </dependency>
+
+        <!-- Testing Dependencies -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.9.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.9.2</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- Maven Compiler Plugin -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.11.0</version>
+                <configuration>
+                    <source>17</source>
+                    <target>17</target>
+                </configuration>
+            </plugin>
+
+            <!-- JavaFX Maven Plugin -->
+            <plugin>
+                <groupId>org.openjfx</groupId>
+                <artifactId>javafx-maven-plugin</artifactId>
+                <version>${javafx.maven.plugin.version}</version>
+                <configuration>
+                    <mainClass>com.personalproject.ui.MathExamGui</mainClass>
+                    <!-- Specify required JavaFX modules -->
+                    <options>
+                        <option>--add-modules</option>
+                        <option>javafx.controls,javafx.fxml,javafx.graphics</option>
+                    </options>
+                </configuration>
+                <executions>
+                    <execution>
+                        <!-- Default execution for run goal -->
+                        <id>default-cli</id>
+                        <configuration>
+                            <mainClass>com.personalproject.ui.MathExamGui</mainClass>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+
+            <!-- Maven Surefire Plugin for testing -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.0.0</version>
+            </plugin>
+
+            <!-- Maven JAR Plugin -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>3.3.0</version>
+                <configuration>
+                    <archive>
+                        <manifest>
+                            <mainClass>com.personalproject.ui.MathExamGui</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+            </plugin>
+            
+            <!-- Maven Shade Plugin to create a fat JAR -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <version>3.4.1</version>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                        <configuration>
+                            <transformers>
+                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+                                    <mainClass>com.personalproject.ui.MathExamGui</mainClass>
+                                </transformer>
+                            </transformers>
+                            <!-- Include all JavaFX modules in the fat JAR -->
+                            <filters>
+                                <filter>
+                                    <artifact>*:*</artifact>
+                                    <excludes>
+                                        <exclude>META-INF/*.SF</exclude>
+                                        <exclude>META-INF/*.DSA</exclude>
+                                        <exclude>META-INF/*.RSA</exclude>
+                                    </excludes>
+                                </filter>
+                            </filters>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

src/main/java/com/personalproject/MathExamApplication.java

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+package com.personalproject;
+
+import com.personalproject.ui.MathExamGui;
+
+/**
+ * 数学学习软件主应用程序入口. 这个类现在启动JavaFX GUI应用程序.
+ */
+public final class MathExamApplication {
+
+  /**
+   * 程序入口：启动JavaFX GUI应用程序.
+   *
+   * @param args 命令行参数，当前未使用.
+   */
+  public static void main(String[] args) {
+    // 启动JavaFX应用程序
+    MathExamGui.main(args);
+  }
+}

src/main/java/com/personalproject/auth/AccountRepository.java

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+package com.personalproject.auth;
+
+import com.personalproject.model.DifficultyLevel;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.time.LocalDateTime;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Properties;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * 存放用户账号并提供认证和注册查询能力.
+ */
+public final class AccountRepository {
+
+  private static final Path ACCOUNTS_DIRECTORY = Paths.get("user_data", "accounts");
+  private static final String FILE_EXTENSION = ".properties";
+
+  private final Map<String, UserAccount> accounts = new ConcurrentHashMap<>();
+
+  /**
+   * 创建账号仓库并立即加载磁盘中的账号数据.
+   */
+  public AccountRepository() {
+    loadAccounts();
+  }
+
+  /**
+   * 根据用户名与密码查找匹配的账号.
+   *
+   * @param username 用户名.
+   * @param password 密码.
+   * @return 匹配成功时返回账号信息，否则返回空结果.
+   */
+  public Optional<UserAccount> authenticate(String username, String password) {
+    if (username == null || password == null) {
+      return Optional.empty();
+    }
+    String normalizedUsername = username.trim();
+    String normalizedPassword = password.trim();
+    UserAccount account = accounts.get(normalizedUsername);
+    if (account == null || !account.isRegistered()) {
+      return Optional.empty();
+    }
+    if (!account.password().equals(hashPassword(normalizedPassword))) {
+      return Optional.empty();
+    }
+    return Optional.of(account);
+  }
+
+  /**
+   * 使用电子邮箱注册新用户账号.
+   *
+   * @param username        用户名
+   * @param email           邮箱地址
+   * @param difficultyLevel 选择的难度级别
+   * @return 若注册成功则返回 true，若用户名已存在则返回 false
+   */
+  public synchronized boolean registerUser(String username, String email,
+      DifficultyLevel difficultyLevel) {
+    if (username == null || email == null || difficultyLevel == null) {
+      return false;
+    }
+
+    String normalizedUsername = username.trim();
+    String normalizedEmail = email.trim();
+    if (normalizedUsername.isEmpty() || normalizedEmail.isEmpty()) {
+      return false;
+    }
+
+    UserAccount existing = accounts.get(normalizedUsername);
+    if (existing != null && existing.isRegistered()) {
+      return false;
+    }
+
+    if (isEmailInUse(normalizedEmail, normalizedUsername)) {
+      return false;
+    }
+
+    LocalDateTime registrationDate =
+        existing != null ? existing.registrationDate() : LocalDateTime.now();
+    UserAccount account = new UserAccount(
+        normalizedUsername,
+        normalizedEmail,
+        "",
+        difficultyLevel,
+        registrationDate,
+        false);
+
+    accounts.put(normalizedUsername, account);
+    persistAccount(account);
+    return true;
+  }
+
+  /**
+   * 在注册后为用户设置密码.
+   *
+   * @param username 用户名
+   * @param password 要设置的密码
+   * @return 设置成功返回 true，若用户不存在则返回 false
+   */
+  public synchronized boolean setPassword(String username, String password) {
+    if (username == null || password == null) {
+      return false;
+    }
+    String normalizedUsername = username.trim();
+    UserAccount account = accounts.get(normalizedUsername);
+    if (account == null || account.isRegistered()) {
+      return false;
+    }
+
+    UserAccount updatedAccount = new UserAccount(
+        account.username(),
+        account.email(),
+        hashPassword(password.trim()),
+        account.difficultyLevel(),
+        account.registrationDate(),
+        true);
+    accounts.put(normalizedUsername, updatedAccount);
+    persistAccount(updatedAccount);
+    return true;
+  }
+
+  /**
+   * 修改现有用户的密码.
+   *
+   * @param username    用户名
+   * @param oldPassword 当前密码
+   * @param newPassword 新密码
+   * @return 修改成功返回 true，若旧密码错误或用户不存在则返回 false
+   */
+  public synchronized boolean changePassword(String username, String oldPassword,
+      String newPassword) {
+    if (username == null || oldPassword == null || newPassword == null) {
+      return false;
+    }
+    String normalizedUsername = username.trim();
+    UserAccount account = accounts.get(normalizedUsername);
+    if (account == null || !account.isRegistered()) {
+      return false;
+    }
+
+    if (!account.password().equals(hashPassword(oldPassword.trim()))) {
+      return false;
+    }
+
+    UserAccount updatedAccount = new UserAccount(
+        account.username(),
+        account.email(),
+        hashPassword(newPassword.trim()),
+        account.difficultyLevel(),
+        account.registrationDate(),
+        true);
+    accounts.put(normalizedUsername, updatedAccount);
+    persistAccount(updatedAccount);
+    return true;
+  }
+
+  /**
+   * 移除未完成注册的用户，便于重新注册.
+   *
+   * @param username 待移除的用户名
+   */
+  public synchronized void removeUnverifiedUser(String username) {
+    if (username == null) {
+      return;
+    }
+    String normalizedUsername = username.trim();
+    UserAccount account = accounts.get(normalizedUsername);
+    if (account != null && !account.isRegistered()) {
+      accounts.remove(normalizedUsername);
+      deleteAccountFile(normalizedUsername);
+    }
+  }
+
+  /**
+   * 检查用户是否存在.
+   *
+   * @param username 待检查的用户名
+   * @return 若存在则返回 true，否则返回 false
+   */
+  public boolean userExists(String username) {
+    if (username == null) {
+      return false;
+    }
+    return accounts.containsKey(username.trim());
+  }
+
+  /**
+   * 按用户名获取用户账户.
+   *
+   * @param username 用户名
+   * @return 若找到则返回包含用户账户的 Optional
+   */
+  public Optional<UserAccount> getUser(String username) {
+    if (username == null) {
+      return Optional.empty();
+    }
+    return Optional.ofNullable(accounts.get(username.trim()));
+  }
+
+  private void loadAccounts() {
+    try {
+      if (!Files.exists(ACCOUNTS_DIRECTORY)) {
+        Files.createDirectories(ACCOUNTS_DIRECTORY);
+        return;
+      }
+
+      try (var paths = Files.list(ACCOUNTS_DIRECTORY)) {
+        paths
+            .filter(path -> path.getFileName().toString().endsWith(FILE_EXTENSION))
+            .forEach(this::loadAccountFromFile);
+      }
+    } catch (IOException exception) {
+      throw new IllegalStateException("加载账户数据失败", exception);
+    }
+  }
+
+  private void loadAccountFromFile(Path file) {
+    Properties properties = new Properties();
+    try (Reader reader = Files.newBufferedReader(file, StandardCharsets.UTF_8)) {
+      properties.load(reader);
+    } catch (IOException exception) {
+      System.err.println("读取账户文件失败: " + file + "，原因: " + exception.getMessage());
+      return;
+    }
+
+    String username = properties.getProperty("username");
+    if (username == null || username.isBlank()) {
+      return;
+    }
+
+    String email = properties.getProperty("email", "");
+    String passwordHash = properties.getProperty("passwordHash", "");
+    String difficultyValue = properties.getProperty("difficulty", DifficultyLevel.PRIMARY.name());
+    String registrationDateValue = properties.getProperty("registrationDate");
+    String registeredValue = properties.getProperty("registered", "false");
+
+    try {
+      DifficultyLevel difficultyLevel = DifficultyLevel.valueOf(difficultyValue);
+      LocalDateTime registrationDate = registrationDateValue == null
+          ? LocalDateTime.now()
+          : LocalDateTime.parse(registrationDateValue);
+      boolean registered = Boolean.parseBoolean(registeredValue);
+      UserAccount account = new UserAccount(
+          username,
+          email,
+          passwordHash,
+          difficultyLevel,
+          registrationDate,
+          registered);
+      accounts.put(username, account);
+    } catch (Exception exception) {
+      System.err.println("解析账户文件失败: " + file + "，原因: " + exception.getMessage());
+    }
+  }
+
+  private void persistAccount(UserAccount account) {
+    Properties properties = new Properties();
+    properties.setProperty("username", account.username());
+    properties.setProperty("email", account.email());
+    properties.setProperty("passwordHash", account.password());
+    properties.setProperty("difficulty", account.difficultyLevel().name());
+    properties.setProperty("registrationDate", account.registrationDate().toString());
+    properties.setProperty("registered", Boolean.toString(account.isRegistered()));
+
+    Path targetFile = accountFile(account.username());
+    try {
+      if (!Files.exists(ACCOUNTS_DIRECTORY)) {
+        Files.createDirectories(ACCOUNTS_DIRECTORY);
+      }
+      try (Writer writer = Files.newBufferedWriter(targetFile, StandardCharsets.UTF_8)) {
+        properties.store(writer, "User account data");
+      }
+    } catch (IOException exception) {
+      throw new IllegalStateException("保存账户数据失败: " + account.username(), exception);
+    }
+  }
+
+  private void deleteAccountFile(String username) {
+    Path file = accountFile(username);
+    try {
+      Files.deleteIfExists(file);
+    } catch (IOException exception) {
+      System.err.println("删除账户文件失败: " + file + "，原因: " + exception.getMessage());
+    }
+  }
+
+  private boolean isEmailInUse(String email, String currentUsername) {
+    return accounts.values().stream()
+        .anyMatch(account -> account.email().equalsIgnoreCase(email)
+            && !account.username().equals(currentUsername));
+  }
+
+  private Path accountFile(String username) {
+    return ACCOUNTS_DIRECTORY.resolve(username + FILE_EXTENSION);
+  }
+
+  private String hashPassword(String password) {
+    try {
+      MessageDigest digest = MessageDigest.getInstance("SHA-256");
+      byte[] hashBytes = digest.digest(password.getBytes(StandardCharsets.UTF_8));
+      return toHex(hashBytes);
+    } catch (NoSuchAlgorithmException exception) {
+      throw new IllegalStateException("当前运行环境不支持SHA-256算法", exception);
+    }
+  }
+
+  private String toHex(byte[] bytes) {
+    StringBuilder builder = new StringBuilder(bytes.length * 2);
+    for (byte value : bytes) {
+      builder.append(String.format("%02x", value));
+    }
+    return builder.toString();
+  }
+}

src/main/java/com/personalproject/auth/EmailService.java

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+package com.personalproject.auth;
+
+import jakarta.mail.Authenticator;
+import jakarta.mail.Message;
+import jakarta.mail.MessagingException;
+import jakarta.mail.PasswordAuthentication;
+import jakarta.mail.Session;
+import jakarta.mail.Transport;
+import jakarta.mail.internet.InternetAddress;
+import jakarta.mail.internet.MimeMessage;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Properties;
+import java.util.Random;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * 用于发送带有注册码的电子邮件的工具类.
+ */
+public final class EmailService {
+
+  private static final String CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+  private static final int CODE_LENGTH = 6;
+  private static final Random RANDOM = new Random();
+  private static final Path OUTBOX_DIRECTORY = Paths.get("user_data", "emails");
+  private static final String CONFIG_RESOURCE = "email-config.properties";
+  private static final DateTimeFormatter DATE_TIME_FORMATTER =
+      DateTimeFormatter.ofPattern("yyyyMMdd-HHmmss");
+  private static final Map<String, String> LAST_CODES = new ConcurrentHashMap<>();
+  private static final AtomicReference<MailConfiguration> CONFIG_CACHE = new AtomicReference<>();
+  private static final String DEFAULT_SUBJECT = "数学学习软件注册验证码";
+
+  private EmailService() {
+    // 防止实例化此工具类
+  }
+
+  /**
+   * 生成随机注册码.
+   *
+   * @return 随机生成的注册码
+   */
+  public static String generateRegistrationCode() {
+    StringBuilder code = new StringBuilder();
+    for (int i = 0; i < CODE_LENGTH; i++) {
+      code.append(CHARACTERS.charAt(RANDOM.nextInt(CHARACTERS.length())));
+    }
+    return code.toString();
+  }
+
+  /**
+   * 将注册码发送到指定邮箱.
+   *
+   * @param email            收件人邮箱
+   * @param registrationCode 要发送的注册码
+   * @return 发送成功返回 true
+   */
+  public static boolean sendRegistrationCode(String email, String registrationCode) {
+    try {
+      MailConfiguration configuration = loadConfiguration();
+      sendEmail(email, registrationCode, configuration);
+      persistMessage(email, registrationCode);
+      LAST_CODES.put(email.trim().toLowerCase(), registrationCode);
+      return true;
+    } catch (Exception exception) {
+      System.err.println("发送验证码失败: " + exception.getMessage());
+      return false;
+    }
+  }
+
+  /**
+   * 获取最近一次发送到指定邮箱的验证码（便于调试或测试）.
+   *
+   * @param email 收件人邮箱
+   * @return 若存在则返回验证码
+   */
+  public static Optional<String> getLastSentRegistrationCode(String email) {
+    if (email == null) {
+      return Optional.empty();
+    }
+    return Optional.ofNullable(LAST_CODES.get(email.trim().toLowerCase()));
+  }
+
+  /**
+   * 校验电子邮件地址的格式是否有效.
+   *
+   * @param email 待校验的邮箱地址
+   * @return 若格式有效则返回 true，否则返回 false
+   */
+  public static boolean isValidEmail(String email) {
+    if (email == null || email.trim().isEmpty()) {
+      return false;
+    }
+
+    String emailRegex = "^[a-zA-Z0-9_+&*-]+(?:\\.[a-zA-Z0-9_+&*-]+)*@"
+        + "(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,7}$";
+    return email.matches(emailRegex);
+  }
+
+  private static MailConfiguration loadConfiguration() throws IOException {
+    MailConfiguration cached = CONFIG_CACHE.get();
+    if (cached != null) {
+      return cached;
+    }
+
+    synchronized (CONFIG_CACHE) {
+      cached = CONFIG_CACHE.get();
+      if (cached != null) {
+        return cached;
+      }
+
+      Properties properties = new Properties();
+      try (InputStream inputStream =
+          EmailService.class.getClassLoader().getResourceAsStream(CONFIG_RESOURCE)) {
+        if (inputStream == null) {
+          throw new IllegalStateException(
+              "类路径下缺少邮箱配置文件: " + CONFIG_RESOURCE
+                  + "，请在 src/main/resources 下提供该文件");
+        }
+        try (InputStreamReader reader =
+            new InputStreamReader(inputStream, StandardCharsets.UTF_8)) {
+          properties.load(reader);
+        }
+      }
+
+      String username = require(properties, "mail.username");
+      final String password = require(properties, "mail.password");
+      final String from = properties.getProperty("mail.from", username);
+      final String subject = properties.getProperty("mail.subject", DEFAULT_SUBJECT);
+
+      Properties smtpProperties = new Properties();
+      for (Map.Entry<Object, Object> entry : properties.entrySet()) {
+        String key = entry.getKey().toString();
+        if (key.startsWith("mail.smtp.")) {
+          smtpProperties.put(key, entry.getValue());
+        }
+      }
+
+      if (!smtpProperties.containsKey("mail.smtp.host")) {
+        throw new IllegalStateException("邮箱配置缺少 mail.smtp.host");
+      }
+      if (!smtpProperties.containsKey("mail.smtp.port")) {
+        throw new IllegalStateException("邮箱配置缺少 mail.smtp.port");
+      }
+
+      smtpProperties.putIfAbsent("mail.smtp.auth", "true");
+      smtpProperties.putIfAbsent("mail.smtp.starttls.enable", "true");
+
+      MailConfiguration configuration =
+          new MailConfiguration(smtpProperties, username, password, from, subject);
+      CONFIG_CACHE.set(configuration);
+      return configuration;
+    }
+  }
+
+  private static void sendEmail(
+      String recipientEmail, String registrationCode, MailConfiguration configuration)
+      throws MessagingException {
+    Session session = Session.getInstance(configuration.smtpProperties(), new Authenticator() {
+      @Override
+      protected PasswordAuthentication getPasswordAuthentication() {
+        return new PasswordAuthentication(configuration.username(), configuration.password());
+      }
+    });
+
+    MimeMessage message = new MimeMessage(session);
+    message.setFrom(new InternetAddress(configuration.from()));
+    message.setRecipients(
+        Message.RecipientType.TO,
+        InternetAddress.parse(recipientEmail, false));
+    message.setSubject(configuration.subject());
+
+    String body = "您好，您的注册码为：" + registrationCode + System.lineSeparator()
+        + "请在10分钟内使用该验证码完成注册。";
+    message.setText(body, StandardCharsets.UTF_8.name());
+
+    Transport.send(message);
+  }
+
+  private static void persistMessage(String email, String registrationCode) throws IOException {
+    if (!Files.exists(OUTBOX_DIRECTORY)) {
+      Files.createDirectories(OUTBOX_DIRECTORY);
+    }
+
+    String sanitizedEmail = sanitizeEmail(email);
+    String timestamp = DATE_TIME_FORMATTER.format(LocalDateTime.now());
+    final Path messageFile = OUTBOX_DIRECTORY.resolve(sanitizedEmail + "_" + timestamp + ".txt");
+    StringBuilder content = new StringBuilder();
+    content.append("收件人: ").append(email).append(System.lineSeparator());
+    content.append("注册码: ").append(registrationCode).append(System.lineSeparator());
+    content.append("发送时间: ").append(LocalDateTime.now()).append(System.lineSeparator());
+
+    Files.writeString(
+        messageFile,
+        content.toString(),
+        StandardCharsets.UTF_8,
+        StandardOpenOption.CREATE_NEW,
+        StandardOpenOption.WRITE);
+  }
+
+  private static String require(Properties properties, String key) {
+    String value = properties.getProperty(key);
+    if (value == null || value.trim().isEmpty()) {
+      throw new IllegalStateException("邮箱配置缺少必要字段: " + key);
+    }
+    return value.trim();
+  }
+
+  private static String sanitizeEmail(String email) {
+    return email.replaceAll("[^a-zA-Z0-9._-]", "_");
+  }
+
+  private record MailConfiguration(
+      Properties smtpProperties,
+      String username,
+      String password,
+      String from,
+      String subject) {
+
+  }
+}

src/main/java/com/personalproject/auth/PasswordValidator.java

@@ -0,0 +1,37 @@
+package com.personalproject.auth;
+
+import java.util.regex.Pattern;
+
+/**
+ * 用于验证密码规则的工具类.
+ */
+public final class PasswordValidator {
+
+  private static final Pattern PASSWORD_PATTERN =
+      Pattern.compile("^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)[a-zA-Z\\d]{6,10}$");
+
+  private PasswordValidator() {
+    // 防止实例化此工具类
+  }
+
+  /**
+   * 校验密码是否满足以下要求.
+   * - 长度 6-10 位
+   * - 至少包含一个大写字母
+   * - 至少包含一个小写字母
+   * - 至少包含一个数字
+   *
+   * @param password 待校验的密码
+   * @return 若满足要求则返回 true，否则返回 false
+   */
+  public static boolean isValidPassword(String password) {
+    if (password == null) {
+      return false;
+    }
+    String normalized = password.trim();
+    if (normalized.isEmpty()) {
+      return false;
+    }
+    return PASSWORD_PATTERN.matcher(normalized).matches();
+  }
+}

src/main/java/com/personalproject/auth/UserAccount.java

@@ -0,0 +1,40 @@
+package com.personalproject.auth;
+
+import com.personalproject.model.DifficultyLevel;
+import java.time.LocalDateTime;
+
+/**
+ * 不可变的账号定义.
+ */
+public record UserAccount(
+    String username,
+    String email,
+    String password,
+    DifficultyLevel difficultyLevel,
+    LocalDateTime registrationDate,
+    boolean isRegistered) {
+
+  /**
+   * 创建新的用户账户，并使用当前时间作为注册时间.
+   *
+   * @param username        用户名
+   * @param email           邮箱地址
+   * @param password        密码
+   * @param difficultyLevel 选择的难度级别
+   * @param isRegistered    用户是否已完成注册
+   */
+  public UserAccount {
+    if (username == null || username.trim().isEmpty()) {
+      throw new IllegalArgumentException("Username cannot be null or empty");
+    }
+    if (email == null || email.trim().isEmpty()) {
+      throw new IllegalArgumentException("Email cannot be null or empty");
+    }
+    if (password == null) {
+      throw new IllegalArgumentException("Password cannot be null");
+    }
+    if (difficultyLevel == null) {
+      throw new IllegalArgumentException("Difficulty level cannot be null");
+    }
+  }
+}

src/main/java/com/personalproject/controller/MathLearningController.java

@@ -0,0 +1,155 @@
+package com.personalproject.controller;
+
+import com.personalproject.generator.QuestionGenerator;
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.model.ExamSession;
+import com.personalproject.service.ExamResultService;
+import com.personalproject.service.MathLearningService;
+import com.personalproject.service.QuestionGenerationService;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * 遵循MVC模式处理应用程序逻辑的控制器类.
+ */
+public final class MathLearningController {
+
+  private final MathLearningService mathLearningService;
+
+  /**
+   * 创建具有所需服务的新控制器.
+   *
+   * @param generatorMap              难度级别到题目生成器的映射
+   * @param questionGenerationService 题目生成服务
+   */
+  public MathLearningController(
+      Map<DifficultyLevel, QuestionGenerator> generatorMap,
+      QuestionGenerationService questionGenerationService) {
+    this.mathLearningService = new MathLearningService(generatorMap, questionGenerationService);
+  }
+
+  /**
+   * 启动用户注册.
+   *
+   * @param username        所需用户名
+   * @param email           用户的电子邮箱地址
+   * @param difficultyLevel 选择的难度级别
+   * @return 注册成功启动则返回true，否则返回false
+   */
+  public boolean initiateRegistration(String username, String email,
+      DifficultyLevel difficultyLevel) {
+    return mathLearningService.initiateRegistration(username, email, difficultyLevel);
+  }
+
+  /**
+   * 验证注册码.
+   *
+   * @param username         用户名
+   * @param registrationCode 注册码
+   * @return 码有效则返回true，否则返回false
+   */
+  public boolean verifyRegistrationCode(String username, String registrationCode) {
+    return mathLearningService.verifyRegistrationCode(username, registrationCode);
+  }
+
+  /**
+   * 注册后设置用户密码.
+   *
+   * @param username 用户名
+   * @param password 要设置的密码
+   * @return 密码设置成功则返回true，否则返回false
+   */
+  public boolean setPassword(String username, String password) {
+    return mathLearningService.setPassword(username, password);
+  }
+
+  /**
+   * 验证用户.
+   *
+   * @param username 用户名
+   * @param password 密码
+   * @return 验证成功则返回包含用户账户的Optional
+   */
+  public Optional<com.personalproject.auth.UserAccount> authenticate(String username,
+      String password) {
+    return mathLearningService.authenticate(username, password);
+  }
+
+  /**
+   * 为用户创建考试会话.
+   *
+   * @param username        用户名
+   * @param difficultyLevel 难度级别
+   * @param questionCount   题目数量
+   * @return 创建的考试会话
+   */
+  public ExamSession createExamSession(String username, DifficultyLevel difficultyLevel,
+      int questionCount) {
+    return mathLearningService.createExamSession(username, difficultyLevel, questionCount);
+  }
+
+  /**
+   * 保存考试结果.
+   *
+   * @param examSession 要保存的考试会话
+   */
+  public void saveExamResults(ExamSession examSession) {
+    mathLearningService.saveExamResults(examSession);
+  }
+
+  /**
+   * 处理考试结果并确定下一步操作.
+   *
+   * @param examSession           完成的考试会话
+   * @param continueWithSameLevel 是否继续相同难度
+   * @param newDifficultyLevel    更改时的新难度（如果不更改则为null）
+   * @return 要执行的下一步操作
+   */
+  public ExamResultService.ExamContinuationAction processExamResult(
+      ExamSession examSession, boolean continueWithSameLevel, DifficultyLevel newDifficultyLevel) {
+    return mathLearningService.processExamResult(examSession, continueWithSameLevel,
+        newDifficultyLevel);
+  }
+
+  /**
+   * 更改用户密码.
+   *
+   * @param username    用户名
+   * @param oldPassword 旧密码
+   * @param newPassword 新密码
+   * @return 密码更改成功则返回true，否则返回false
+   */
+  public boolean changePassword(String username, String oldPassword, String newPassword) {
+    return mathLearningService.changePassword(username, oldPassword, newPassword);
+  }
+
+  /**
+   * 验证密码.
+   *
+   * @param password 要验证的密码
+   * @return 密码有效则返回true，否则返回false
+   */
+  public boolean isValidPassword(String password) {
+    return MathLearningService.isValidPassword(password);
+  }
+
+  /**
+   * 验证电子邮箱地址.
+   *
+   * @param email 要验证的邮箱
+   * @return 邮箱有效则返回true，否则返回false
+   */
+  public boolean isValidEmail(String email) {
+    return MathLearningService.isValidEmail(email);
+  }
+
+  /**
+   * 按用户名获取用户账户.
+   *
+   * @param username 用户名
+   * @return 若找到则返回包含用户账户的 Optional
+   */
+  public Optional<com.personalproject.auth.UserAccount> getUserAccount(String username) {
+    return mathLearningService.getUser(username);
+  }
+}

src/main/java/com/personalproject/generator/HighSchoolQuestionGenerator.java

@@ -0,0 +1,37 @@
+package com.personalproject.generator;
+
+import java.util.Random;
+
+/**
+ * 生成至少包含一种三角函数的高中难度题目表达式.
+ */
+public final class HighSchoolQuestionGenerator implements QuestionGenerator {
+
+  private static final String[] OPERATORS = {"+", "-", "*", "/"};
+  private static final String[] TRIG_FUNCTIONS = {"sin", "cos", "tan"};
+
+  @Override
+  public String generateQuestion(Random random) {
+    int operandCount = random.nextInt(5) + 1;
+    String[] operands = new String[operandCount];
+    for (int index = 0; index < operandCount; index++) {
+      operands[index] = String.valueOf(random.nextInt(100) + 1);
+    }
+    int specialIndex = random.nextInt(operandCount);
+    String function = TRIG_FUNCTIONS[random.nextInt(TRIG_FUNCTIONS.length)];
+    operands[specialIndex] = function + '(' + operands[specialIndex] + ')';
+    StringBuilder builder = new StringBuilder();
+    for (int index = 0; index < operandCount; index++) {
+      if (index > 0) {
+        String operator = OPERATORS[random.nextInt(OPERATORS.length)];
+        builder.append(' ').append(operator).append(' ');
+      }
+      builder.append(operands[index]);
+    }
+    String expression = builder.toString();
+    if (operandCount > 1 && random.nextBoolean()) {
+      return '(' + expression + ')';
+    }
+    return expression;
+  }
+}

src/main/java/com/personalproject/generator/MiddleSchoolQuestionGenerator.java

@@ -0,0 +1,39 @@
+package com.personalproject.generator;
+
+import java.util.Random;
+
+/**
+ * 生成包含平方或开根号运算的初中难度题目表达式.
+ */
+public final class MiddleSchoolQuestionGenerator implements QuestionGenerator {
+
+  private static final String[] OPERATORS = {"+", "-", "*", "/"};
+
+  @Override
+  public String generateQuestion(Random random) {
+    int operandCount = random.nextInt(5) + 1;
+    String[] operands = new String[operandCount];
+    for (int index = 0; index < operandCount; index++) {
+      operands[index] = String.valueOf(random.nextInt(100) + 1);
+    }
+    int specialIndex = random.nextInt(operandCount);
+    if (random.nextBoolean()) {
+      operands[specialIndex] = '(' + operands[specialIndex] + ")^2";
+    } else {
+      operands[specialIndex] = "sqrt(" + operands[specialIndex] + ')';
+    }
+    StringBuilder builder = new StringBuilder();
+    for (int index = 0; index < operandCount; index++) {
+      if (index > 0) {
+        String operator = OPERATORS[random.nextInt(OPERATORS.length)];
+        builder.append(' ').append(operator).append(' ');
+      }
+      builder.append(operands[index]);
+    }
+    String expression = builder.toString();
+    if (operandCount > 1 && random.nextBoolean()) {
+      return '(' + expression + ')';
+    }
+    return expression;
+  }
+}

src/main/java/com/personalproject/generator/PrimaryQuestionGenerator.java

@@ -0,0 +1,119 @@
+package com.personalproject.generator;
+
+import com.personalproject.model.QuizQuestion;
+import com.personalproject.service.MathExpressionEvaluator;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Random;
+import java.util.Set;
+
+/**
+ * 生成包含基础四则运算的小学难度题目表达式.
+ */
+public final class PrimaryQuestionGenerator implements QuestionGenerator, QuizQuestionGenerator {
+
+  private static final String[] OPERATORS = {"+", "-", "*", "/"};
+  private static final int OPTIONS_COUNT = 4;
+
+  @Override
+  public String generateQuestion(Random random) {
+    // 至少生成两个操作数，避免题目退化成单个数字
+    int operandCount = random.nextInt(4) + 2;
+    StringBuilder builder = new StringBuilder();
+    for (int index = 0; index < operandCount; index++) {
+      if (index > 0) {
+        String operator = OPERATORS[random.nextInt(OPERATORS.length)];
+        builder.append(' ').append(operator).append(' ');
+      }
+      int value = random.nextInt(100) + 1;
+      builder.append(value);
+    }
+    String expression = builder.toString();
+    if (operandCount > 1 && random.nextBoolean()) {
+      return '(' + expression + ')';
+    }
+    return expression;
+  }
+
+  @Override
+  public QuizQuestion generateQuizQuestion(Random random) {
+    // 生成数学表达式
+    int operandCount = random.nextInt(4) + 2;
+    StringBuilder builder = new StringBuilder();
+    for (int index = 0; index < operandCount; index++) {
+      if (index > 0) {
+        String operator = OPERATORS[random.nextInt(OPERATORS.length)];
+        builder.append(' ').append(operator).append(' ');
+      }
+      int value = random.nextInt(100) + 1;
+      builder.append(value);
+    }
+    String expression = builder.toString();
+    if (operandCount > 1 && random.nextBoolean()) {
+      expression = '(' + expression + ')';
+    }
+
+    // 直接计算正确答案
+    double correctAnswer;
+    try {
+      correctAnswer = MathExpressionEvaluator.evaluate(expression);
+    } catch (Exception e) {
+      // 如果计算失败则使用兜底值
+      correctAnswer = 0.0;
+    }
+
+    List<String> options = generateOptions(correctAnswer, random);
+    String correctOption = formatOption(correctAnswer);
+    int correctAnswerIndex = options.indexOf(correctOption);
+    if (correctAnswerIndex < 0) {
+      // 兜底逻辑：确保正确答案存在于选项中
+      options.set(0, correctOption);
+      correctAnswerIndex = 0;
+    }
+
+    return new QuizQuestion(expression, options, correctAnswerIndex);
+  }
+
+  /**
+   * 生成选择题选项.
+   */
+  private List<String> generateOptions(double correctAnswer, Random random) {
+    String correctOption = formatOption(correctAnswer);
+    Set<String> optionSet = new LinkedHashSet<>();
+    optionSet.add(correctOption);
+
+    double scale = Math.max(Math.abs(correctAnswer) * 0.2, 1.0);
+    int attempts = 0;
+    while (optionSet.size() < OPTIONS_COUNT && attempts < 100) {
+      double delta = random.nextGaussian() * scale;
+      if (Math.abs(delta) < 0.5) {
+        double direction = random.nextBoolean() ? 1 : -1;
+        delta = direction * (0.5 + random.nextDouble()) * scale;
+      }
+      double candidate = correctAnswer + delta;
+      if (Double.isNaN(candidate) || Double.isInfinite(candidate)) {
+        attempts++;
+        continue;
+      }
+      optionSet.add(formatOption(candidate));
+      attempts++;
+    }
+
+    double step = Math.max(scale, 1.0);
+    while (optionSet.size() < OPTIONS_COUNT) {
+      double candidate = correctAnswer + step * optionSet.size();
+      optionSet.add(formatOption(candidate));
+      step += 1.0;
+    }
+
+    List<String> options = new ArrayList<>(optionSet);
+    Collections.shuffle(options, random);
+    return options;
+  }
+
+  private String formatOption(double value) {
+    return String.format("%.2f", value);
+  }
+}

src/main/java/com/personalproject/generator/QuestionGenerator.java

@@ -0,0 +1,17 @@
+package com.personalproject.generator;
+
+import java.util.Random;
+
+/**
+ * 负责生成单条数学题目的表达式.
+ */
+public interface QuestionGenerator {
+
+  /**
+   * 基于提供的随机数生成器构造一道题目的表达式.
+   *
+   * @param random 用于生成随机数的实例.
+   * @return 生成的题目表达式.
+   */
+  String generateQuestion(Random random);
+}

src/main/java/com/personalproject/generator/QuizQuestionGenerator.java

@@ -0,0 +1,18 @@
+package com.personalproject.generator;
+
+import com.personalproject.model.QuizQuestion;
+import java.util.Random;
+
+/**
+ * 负责生成带答案的数学题目.
+ */
+public interface QuizQuestionGenerator {
+
+  /**
+   * 基于提供的随机数生成器构造一道带答案的题目.
+   *
+   * @param random 用于生成随机数的实例.
+   * @return 生成的带答案的题目.
+   */
+  QuizQuestion generateQuizQuestion(Random random);
+}

src/main/java/com/personalproject/model/DifficultyLevel.java

@@ -0,0 +1,49 @@
+package com.personalproject.model;
+
+import java.util.Optional;
+
+/**
+ * 系统支持的出题难度级别.
+ */
+public enum DifficultyLevel {
+  PRIMARY("小学"),
+  MIDDLE("初中"),
+  HIGH("高中");
+
+  private final String displayName;
+
+  DifficultyLevel(String displayName) {
+    this.displayName = displayName;
+  }
+
+  /**
+   * 获取当前难度对应的展示名称.
+   *
+   * @return 难度的展示名称.
+   */
+  public String getDisplayName() {
+    return displayName;
+  }
+
+  /**
+   * 根据展示名称查找对应的难度枚举值.
+   *
+   * @param name 展示名称.
+   * @return 匹配到的难度枚举，可空返回.
+   */
+  public static Optional<DifficultyLevel> fromDisplayName(String name) {
+    if (name == null) {
+      return Optional.empty();
+    }
+    String trimmed = name.trim();
+    if (trimmed.isEmpty()) {
+      return Optional.empty();
+    }
+    for (DifficultyLevel level : values()) {
+      if (level.displayName.equals(trimmed)) {
+        return Optional.of(level);
+      }
+    }
+    return Optional.empty();
+  }
+}

src/main/java/com/personalproject/model/ExamSession.java

@@ -0,0 +1,255 @@
+package com.personalproject.model;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * 表示用户的考试会话.
+ */
+public final class ExamSession {
+
+  private final String username;
+  private final DifficultyLevel difficultyLevel;
+  private final List<QuizQuestion> questions;
+  private final List<Integer> userAnswers;
+  private final LocalDateTime startTime;
+  private int currentQuestionIndex;
+
+  /**
+   * 创建新的考试会话.
+   *
+   * @param username        考生的用户名
+   * @param difficultyLevel 考试的难度级别
+   * @param questions       考试题目列表
+   */
+  public ExamSession(String username, DifficultyLevel difficultyLevel,
+      List<QuizQuestion> questions) {
+    if (username == null || username.trim().isEmpty()) {
+      throw new IllegalArgumentException("Username cannot be null or empty");
+    }
+    if (difficultyLevel == null) {
+      throw new IllegalArgumentException("Difficulty level cannot be null");
+    }
+    if (questions == null || questions.isEmpty()) {
+      throw new IllegalArgumentException("Questions list cannot be null or empty");
+    }
+
+    this.username = username;
+    this.difficultyLevel = difficultyLevel;
+    this.questions = List.copyOf(questions); // 题目的不可变副本
+    this.userAnswers = new ArrayList<>(Collections.nCopies(questions.size(), -1));
+    this.startTime = LocalDateTime.now();
+    this.currentQuestionIndex = 0;
+  }
+
+  /**
+   * 获取考生的用户名.
+   *
+   * @return 用户名
+   */
+  public String getUsername() {
+    return username;
+  }
+
+  /**
+   * 获取考试的难度级别.
+   *
+   * @return 考试难度级别
+   */
+  public DifficultyLevel getDifficultyLevel() {
+    return difficultyLevel;
+  }
+
+  /**
+   * 获取考试中的题目列表.
+   *
+   * @return 不可修改的题目列表
+   */
+  public List<QuizQuestion> getQuestions() {
+    return questions;
+  }
+
+  /**
+   * 获取用户对各题的作答.
+   *
+   * @return 答案索引列表（-1 表示未选择）
+   */
+  public List<Integer> getUserAnswers() {
+    return List.copyOf(userAnswers); // 返回副本以防止被修改
+  }
+
+  /**
+   * 获取当前题目的索引.
+   *
+   * @return 当前题目索引
+   */
+  public int getCurrentQuestionIndex() {
+    return currentQuestionIndex;
+  }
+
+  /**
+   * 为当前题目记录用户的答案.
+   *
+   * @param answerIndex 选中答案的索引
+   */
+  public void setAnswer(int answerIndex) {
+    if (currentQuestionIndex < 0 || currentQuestionIndex >= questions.size()) {
+      throw new IllegalStateException("No valid question at current index");
+    }
+    int optionCount = questions.get(currentQuestionIndex).getOptions().size();
+    if (answerIndex < 0 || answerIndex >= optionCount) {
+      throw new IllegalArgumentException("Invalid answer index");
+    }
+    userAnswers.set(currentQuestionIndex, answerIndex);
+  }
+
+  /**
+   * 跳转到下一题.
+   *
+   * @return 若成功跳转则返回 true，若已是最后一题则返回 false
+   */
+  public boolean goToNextQuestion() {
+    if (currentQuestionIndex < questions.size() - 1) {
+      currentQuestionIndex++;
+      return true;
+    }
+    return false;
+  }
+
+  /**
+   * 返回上一题.
+   *
+   * @return 若成功返回则返回 true，若已是第一题则返回 false
+   */
+  public boolean goToPreviousQuestion() {
+    if (currentQuestionIndex > 0) {
+      currentQuestionIndex--;
+      return true;
+    }
+    return false;
+  }
+
+  /**
+   * 检查考试是否完成（所有题目已作答或到达最后一题）.
+   *
+   * @return 若考试已完成则返回 true，否则返回 false
+   */
+  public boolean isComplete() {
+    return userAnswers.stream().allMatch(answer -> answer != -1);
+  }
+
+  /**
+   * 获取当前题目.
+   *
+   * @return 当前的测验题
+   */
+  public QuizQuestion getCurrentQuestion() {
+    if (currentQuestionIndex < 0 || currentQuestionIndex >= questions.size()) {
+      throw new IllegalStateException("No valid question at current index");
+    }
+    return questions.get(currentQuestionIndex);
+  }
+
+  /**
+   * 获取指定题目的用户答案.
+   *
+   * @param questionIndex 题目索引
+   * @return 用户答案的索引（未选择时为 -1）
+   */
+  public int getUserAnswer(int questionIndex) {
+    if (questionIndex < 0 || questionIndex >= questions.size()) {
+      throw new IllegalArgumentException("Question index out of bounds");
+    }
+    return userAnswers.get(questionIndex);
+  }
+
+  /**
+   * 计算得分百分比.
+   *
+   * @return 0-100 范围内的得分百分比
+   */
+  public double calculateScore() {
+    int correctCount = 0;
+    for (int i = 0; i < questions.size(); i++) {
+      QuizQuestion question = questions.get(i);
+      int userAnswer = userAnswers.get(i);
+      if (userAnswer != -1 && question.isAnswerCorrect(userAnswer)) {
+        correctCount++;
+      }
+    }
+    return questions.isEmpty() ? 0.0 : (double) correctCount / questions.size() * 100.0;
+  }
+
+  /**
+   * 获取考试中的题目总数.
+   *
+   * @return 题目总数
+   */
+  public int getTotalQuestions() {
+    return questions.size();
+  }
+
+  /**
+   * 检查指定题目是否已作答.
+   *
+   * @param questionIndex 题目索引
+   * @return 若已作答则返回 true，否则返回 false
+   */
+  public boolean hasAnswered(int questionIndex) {
+    if (questionIndex < 0 || questionIndex >= questions.size()) {
+      throw new IllegalArgumentException("Question index out of bounds");
+    }
+    return userAnswers.get(questionIndex) != -1;
+  }
+
+  /**
+   * 获取考试开始时间.
+   *
+   * @return 开始时间
+   */
+  public LocalDateTime getStartTime() {
+    return startTime;
+  }
+
+  /**
+   * 获取答对的题目数量.
+   *
+   * @return 正确题目数量
+   */
+  public int getCorrectAnswersCount() {
+    int correctCount = 0;
+    for (int i = 0; i < questions.size(); i++) {
+      QuizQuestion question = questions.get(i);
+      int userAnswer = userAnswers.get(i);
+      if (userAnswer != -1 && question.isAnswerCorrect(userAnswer)) {
+        correctCount++;
+      }
+    }
+    return correctCount;
+  }
+
+  /**
+   * 获取答错的题目数量.
+   *
+   * @return 错误题目数量
+   */
+  public int getIncorrectAnswersCount() {
+    int totalAnswered = 0;
+    int correctCount = 0;
+
+    for (int i = 0; i < questions.size(); i++) {
+      int userAnswer = userAnswers.get(i);
+      if (userAnswer != -1) {
+        totalAnswered++;
+        QuizQuestion question = questions.get(i);
+        if (question.isAnswerCorrect(userAnswer)) {
+          correctCount++;
+        }
+      }
+    }
+
+    return totalAnswered - correctCount;
+  }
+}

src/main/java/com/personalproject/model/QuizQuestion.java

@@ -0,0 +1,73 @@
+package com.personalproject.model;
+
+import java.util.List;
+
+/**
+ * 表示一个带有多项选择的测验题目.
+ */
+public final class QuizQuestion {
+
+  private final String questionText;
+  private final List<String> options;
+  private final int correctAnswerIndex;
+
+  /**
+   * 创建新的测验题目.
+   *
+   * @param questionText       题目文本
+   * @param options            答案选项列表
+   * @param correctAnswerIndex 正确答案在选项列表中的索引
+   */
+  public QuizQuestion(String questionText, List<String> options, int correctAnswerIndex) {
+    if (questionText == null || questionText.trim().isEmpty()) {
+      throw new IllegalArgumentException("Question text cannot be null or empty");
+    }
+    if (options == null || options.size() < 2) {
+      throw new IllegalArgumentException("Options must contain at least 2 choices");
+    }
+    if (correctAnswerIndex < 0 || correctAnswerIndex >= options.size()) {
+      throw new IllegalArgumentException("Correct answer index out of bounds");
+    }
+
+    this.questionText = questionText;
+    this.options = List.copyOf(options); // 不可变副本
+    this.correctAnswerIndex = correctAnswerIndex;
+  }
+
+  /**
+   * 获取题目文本.
+   *
+   * @return 题目文本
+   */
+  public String getQuestionText() {
+    return questionText;
+  }
+
+  /**
+   * 获取答案选项列表.
+   *
+   * @return 不可修改的答案选项列表
+   */
+  public List<String> getOptions() {
+    return options;
+  }
+
+  /**
+   * 获取正确答案在选项列表中的索引.
+   *
+   * @return 正确答案的索引
+   */
+  public int getCorrectAnswerIndex() {
+    return correctAnswerIndex;
+  }
+
+  /**
+   * 检查给定的答案索引是否正确.
+   *
+   * @param answerIndex 用户答案的索引
+   * @return 若答案正确则返回 true，否则返回 false
+   */
+  public boolean isAnswerCorrect(int answerIndex) {
+    return answerIndex == correctAnswerIndex;
+  }
+}

src/main/java/com/personalproject/service/ExamResultService.java

@@ -0,0 +1,83 @@
+package com.personalproject.service;
+
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.model.ExamSession;
+
+/**
+ * 用于处理考试后选项（如继续或退出）的服务.
+ */
+public final class ExamResultService {
+
+  /**
+   * 评估用户在完成考试后的选择.
+   *
+   * @param examSession           完成的考试会话
+   * @param continueWithSameLevel 是否使用相同难度级别继续
+   * @param newDifficultyLevel    更改时的新难度级别（如果不更改则为null）
+   * @return 指示下一步操作的操作
+   */
+  public ExamContinuationAction processExamResult(
+      ExamSession examSession, boolean continueWithSameLevel, DifficultyLevel newDifficultyLevel) {
+
+    if (continueWithSameLevel) {
+      return new ExamContinuationAction(
+          true, examSession.getDifficultyLevel(), (int) examSession.getQuestions().size());
+    } else if (newDifficultyLevel != null) {
+      return new ExamContinuationAction(true, newDifficultyLevel,
+          (int) examSession.getQuestions().size());
+    } else {
+      return new ExamContinuationAction(false, null, 0);
+    }
+  }
+
+  /**
+   * 表示完成考试后要采取的操作.
+   */
+  public static final class ExamContinuationAction {
+
+    private final boolean shouldContinue;
+    private final DifficultyLevel nextDifficultyLevel;
+    private final int nextQuestionCount;
+
+    /**
+     * 创建新的考试延续操作.
+     *
+     * @param shouldContinue      用户是否想继续参加另一次考试
+     * @param nextDifficultyLevel 下次考试的难度级别（如果不继续则为null）
+     * @param nextQuestionCount   下次考试的题目数量（如果不继续则为0）
+     */
+    public ExamContinuationAction(
+        boolean shouldContinue, DifficultyLevel nextDifficultyLevel, int nextQuestionCount) {
+      this.shouldContinue = shouldContinue;
+      this.nextDifficultyLevel = nextDifficultyLevel;
+      this.nextQuestionCount = nextQuestionCount;
+    }
+
+    /**
+     * 获取用户是否想继续参加另一次考试.
+     *
+     * @return 如果继续则为true，如果退出则为false
+     */
+    public boolean shouldContinue() {
+      return shouldContinue;
+    }
+
+    /**
+     * 获取下次考试的难度级别.
+     *
+     * @return 下次难度级别（如果不继续则为null）
+     */
+    public DifficultyLevel getNextDifficultyLevel() {
+      return nextDifficultyLevel;
+    }
+
+    /**
+     * 获取下次考试的题目数量.
+     *
+     * @return 下次题目数量（如果不继续则为0）
+     */
+    public int getNextQuestionCount() {
+      return nextQuestionCount;
+    }
+  }
+}

src/main/java/com/personalproject/service/ExamService.java

@@ -0,0 +1,158 @@
+package com.personalproject.service;
+
+import com.personalproject.generator.QuestionGenerator;
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.model.ExamSession;
+import com.personalproject.model.QuizQuestion;
+import com.personalproject.storage.QuestionStorageService;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+
+/**
+ * 用于管理考试会话和生成测验题目的服务类.
+ */
+public final class ExamService {
+
+  private static final int OPTIONS_COUNT = 4;
+  private final Map<DifficultyLevel, QuestionGenerator> generators;
+  private final Random random = new Random();
+  private final QuestionGenerationService questionGenerationService;
+  private final QuestionStorageService questionStorageService;
+
+  /**
+   * 创建新的考试服务.
+   *
+   * @param generatorMap              难度级别到题目生成器的映射
+   * @param questionGenerationService 题目生成服务
+   * @param questionStorageService    题目存储服务
+   */
+  public ExamService(
+      Map<DifficultyLevel, QuestionGenerator> generatorMap,
+      QuestionGenerationService questionGenerationService,
+      QuestionStorageService questionStorageService) {
+    this.generators = new EnumMap<>(DifficultyLevel.class);
+    this.generators.putAll(generatorMap);
+    this.questionGenerationService = questionGenerationService;
+    this.questionStorageService = questionStorageService;
+  }
+
+  /**
+   * 使用指定参数创建新的考试会话.
+   *
+   * @param username        考生用户名
+   * @param difficultyLevel 考试难度级别
+   * @param questionCount   考试中包含的题目数量
+   * @return 新的考试会话
+   */
+  public ExamSession createExamSession(
+      String username, DifficultyLevel difficultyLevel, int questionCount) {
+    if (questionCount < 10 || questionCount > 30) {
+      throw new IllegalArgumentException("题目数量必须在10到30之间");
+    }
+
+    // 根据难度级别生成题目
+    if (!generators.containsKey(difficultyLevel)) {
+      throw new IllegalArgumentException("找不到难度级别的生成器: " + difficultyLevel);
+    }
+
+    try {
+      Set<String> existingQuestions = questionStorageService.loadExistingQuestions(username);
+      List<String> uniqueQuestions = questionGenerationService.generateUniqueQuestions(
+          difficultyLevel, questionCount, existingQuestions);
+
+      List<QuizQuestion> quizQuestions = new ArrayList<>();
+      for (String questionText : uniqueQuestions) {
+        quizQuestions.add(buildQuizQuestion(questionText));
+      }
+
+      questionStorageService.saveQuestions(username, uniqueQuestions);
+      return new ExamSession(username, difficultyLevel, quizQuestions);
+    } catch (IOException exception) {
+      throw new IllegalStateException("生成考试题目失败", exception);
+    }
+  }
+
+  /**
+   * 使用预定义题目创建考试会话（用于测试）.
+   *
+   * @param username        考生用户名
+   * @param difficultyLevel 考试难度级别
+   * @param questions       预定义题目列表
+   * @return 新的考试会话
+   */
+  public ExamSession createExamSession(
+      String username, DifficultyLevel difficultyLevel, List<QuizQuestion> questions) {
+    if (questions.size() < 10 || questions.size() > 30) {
+      throw new IllegalArgumentException("题目数量必须在10到30之间");
+    }
+    return new ExamSession(username, difficultyLevel, questions);
+  }
+
+  private QuizQuestion buildQuizQuestion(String questionText) {
+    try {
+      double correctAnswer = MathExpressionEvaluator.evaluate(questionText);
+      String formattedCorrectAnswer = formatAnswer(correctAnswer);
+      List<String> options = buildOptions(correctAnswer, formattedCorrectAnswer);
+      int correctAnswerIndex = options.indexOf(formattedCorrectAnswer);
+      if (correctAnswerIndex < 0) {
+        options.set(0, formattedCorrectAnswer);
+        correctAnswerIndex = 0;
+      }
+      return new QuizQuestion(questionText, options, correctAnswerIndex);
+    } catch (RuntimeException exception) {
+      List<String> fallbackOptions = new ArrayList<>();
+      for (int i = 1; i <= OPTIONS_COUNT; i++) {
+        fallbackOptions.add("选项" + i);
+      }
+      return new QuizQuestion(questionText, fallbackOptions, 0);
+    }
+  }
+
+  private List<String> buildOptions(double correctAnswer, String formattedCorrectAnswer) {
+    Set<String> optionSet = new LinkedHashSet<>();
+    optionSet.add(formattedCorrectAnswer);
+
+    int attempts = 0;
+    while (optionSet.size() < OPTIONS_COUNT && attempts < 100) {
+      double offset = generateOffset(correctAnswer);
+      double candidateValue = correctAnswer + offset;
+      if (Double.isNaN(candidateValue) || Double.isInfinite(candidateValue)) {
+        attempts++;
+        continue;
+      }
+      String candidate = formatAnswer(candidateValue);
+      if (!candidate.equals(formattedCorrectAnswer)) {
+        optionSet.add(candidate);
+      }
+      attempts++;
+    }
+
+    while (optionSet.size() < OPTIONS_COUNT) {
+      optionSet.add(formatAnswer(correctAnswer + optionSet.size() * 1.5));
+    }
+
+    List<String> options = new ArrayList<>(optionSet);
+    Collections.shuffle(options, random);
+    return options;
+  }
+
+  private double generateOffset(double base) {
+    double scale = Math.max(1.0, Math.abs(base) / 2.0);
+    double offset = random.nextGaussian() * scale;
+    if (Math.abs(offset) < 0.5) {
+      offset += offset >= 0 ? 1.5 : -1.5;
+    }
+    return offset;
+  }
+
+  private String formatAnswer(double value) {
+    return String.format("%.2f", value);
+  }
+}

src/main/java/com/personalproject/service/MathExpressionEvaluator.java

@@ -0,0 +1,269 @@
+package com.personalproject.service;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Stack;
+import java.util.function.DoubleUnaryOperator;
+import java.util.regex.Pattern;
+
+/**
+ * 可处理基本算术运算的数学表达式求值器.
+ */
+public final class MathExpressionEvaluator {
+
+  private static final Pattern NUMBER_PATTERN = Pattern.compile("-?\\d+(\\.\\d+)?");
+  private static final Map<Character, Integer> PRECEDENCE = new HashMap<>();
+  private static final Map<String, DoubleUnaryOperator> FUNCTIONS = new HashMap<>();
+
+  static {
+    PRECEDENCE.put('+', 1);
+    PRECEDENCE.put('-', 1);
+    PRECEDENCE.put('*', 2);
+    PRECEDENCE.put('/', 2);
+    PRECEDENCE.put('^', 3);
+
+    FUNCTIONS.put("sin", angle -> Math.sin(Math.toRadians(angle)));
+    FUNCTIONS.put("cos", angle -> Math.cos(Math.toRadians(angle)));
+    FUNCTIONS.put("tan", angle -> Math.tan(Math.toRadians(angle)));
+    FUNCTIONS.put("sqrt", Math::sqrt);
+  }
+
+  private MathExpressionEvaluator() {
+    // 防止实例化此工具类
+  }
+
+  /**
+   * 计算数学表达式字符串的结果.
+   *
+   * @param expression 要计算的数学表达式
+   * @return 计算结果
+   * @throws IllegalArgumentException 如果表达式无效
+   */
+  public static double evaluate(String expression) {
+    if (expression == null) {
+      throw new IllegalArgumentException("Expression cannot be null");
+    }
+
+    expression = expression.replaceAll("\\s+", ""); // 移除空白字符
+    if (expression.isEmpty()) {
+      throw new IllegalArgumentException("Expression cannot be empty");
+    }
+
+    // 将表达式拆分为记号
+    String[] tokens = tokenize(expression);
+
+    // 使用调度场算法将中缀表达式转换为后缀表达式
+    String[] postfix = infixToPostfix(tokens);
+
+    // 计算后缀表达式
+    return evaluatePostfix(postfix);
+  }
+
+  /**
+   * 将表达式拆分为数字与运算符的记号.
+   *
+   * @param expression 待拆分的表达式
+   * @return 记号数组
+   */
+  private static String[] tokenize(String expression) {
+    java.util.List<String> tokens = new java.util.ArrayList<>();
+    StringBuilder currentNumber = new StringBuilder();
+
+    for (int i = 0; i < expression.length(); i++) {
+      char c = expression.charAt(i);
+
+      if (Character.isDigit(c) || c == '.') {
+        currentNumber.append(c);
+      } else if (Character.isLetter(c)) {
+        if (currentNumber.length() > 0) {
+          tokens.add(currentNumber.toString());
+          currentNumber.setLength(0);
+        }
+        StringBuilder functionBuilder = new StringBuilder();
+        functionBuilder.append(c);
+        while (i + 1 < expression.length() && Character.isLetter(expression.charAt(i + 1))) {
+          functionBuilder.append(expression.charAt(++i));
+        }
+        String function = functionBuilder.toString();
+        if (!isFunction(function)) {
+          throw new IllegalArgumentException("Unsupported function: " + function);
+        }
+        tokens.add(function);
+      } else if (c == '(' || c == ')') {
+        if (currentNumber.length() > 0) {
+          tokens.add(currentNumber.toString());
+          currentNumber.setLength(0);
+        }
+        tokens.add(String.valueOf(c));
+      } else if (isOperator(c)) {
+        if (currentNumber.length() > 0) {
+          tokens.add(currentNumber.toString());
+          currentNumber.setLength(0);
+        }
+
+        // 处理一元负号
+        if (c == '-' && (i == 0 || expression.charAt(i - 1) == '(')) {
+          currentNumber.append(c);
+        } else {
+          tokens.add(String.valueOf(c));
+        }
+      } else {
+        throw new IllegalArgumentException("Invalid character in expression: " + c);
+      }
+    }
+
+    if (currentNumber.length() > 0) {
+      tokens.add(currentNumber.toString());
+    }
+
+    return tokens.toArray(new String[0]);
+  }
+
+  /**
+   * 检查字符是否为运算符.
+   *
+   * @param c 待检查的字符
+   * @return 若字符是运算符则返回 true，否则返回 false
+   */
+  private static boolean isOperator(char c) {
+    return c == '+' || c == '-' || c == '*' || c == '/' || c == '^';
+  }
+
+  private static boolean isFunction(String token) {
+    return FUNCTIONS.containsKey(token);
+  }
+
+  /**
+   * 使用调度场算法将中缀表达式转换为后缀表达式.
+   *
+   * @param tokens 中缀表达式的记号数组
+   * @return 后缀表达式的记号数组
+   */
+  private static String[] infixToPostfix(String[] tokens) {
+    java.util.List<String> output = new java.util.ArrayList<>();
+    Stack<String> operators = new Stack<>();
+
+    for (String token : tokens) {
+      if (isNumber(token)) {
+        output.add(token);
+      } else if (isFunction(token)) {
+        operators.push(token);
+      } else if (token.equals("(")) {
+        operators.push(token);
+      } else if (token.equals(")")) {
+        while (!operators.isEmpty() && !operators.peek().equals("(")) {
+          output.add(operators.pop());
+        }
+        if (!operators.isEmpty()) {
+          operators.pop(); // 移除 "("
+        }
+        if (!operators.isEmpty() && isFunction(operators.peek())) {
+          output.add(operators.pop());
+        }
+      } else if (isOperator(token.charAt(0))) {
+        while (!operators.isEmpty()
+            && isOperator(operators.peek().charAt(0))
+            && PRECEDENCE.get(operators.peek().charAt(0)) >= PRECEDENCE.get(token.charAt(0))) {
+          output.add(operators.pop());
+        }
+        operators.push(token);
+      }
+    }
+
+    while (!operators.isEmpty()) {
+      String operator = operators.pop();
+      if (operator.equals("(") || operator.equals(")")) {
+        throw new IllegalArgumentException("Mismatched parentheses in expression");
+      }
+      output.add(operator);
+    }
+
+    return output.toArray(new String[0]);
+  }
+
+  /**
+   * 计算后缀表达式的值.
+   *
+   * @param postfix 后缀表达式的记号数组
+   * @return 计算结果
+   */
+  private static double evaluatePostfix(String[] postfix) {
+    Stack<Double> values = new Stack<>();
+
+    for (String token : postfix) {
+      if (isNumber(token)) {
+        values.push(Double.parseDouble(token));
+      } else if (isOperator(token.charAt(0))) {
+        if (values.size() < 2) {
+          throw new IllegalArgumentException("Invalid expression: insufficient operands");
+        }
+
+        double b = values.pop();
+        double a = values.pop();
+        double result = performOperation(a, b, token.charAt(0));
+        values.push(result);
+      } else if (isFunction(token)) {
+        if (values.isEmpty()) {
+          throw new IllegalArgumentException(
+              "Invalid expression: insufficient operands for function");
+        }
+        double value = values.pop();
+        values.push(applyFunction(token, value));
+      } else {
+        throw new IllegalArgumentException("Unknown token: " + token);
+      }
+    }
+
+    if (values.size() != 1) {
+      throw new IllegalArgumentException("Invalid expression: too many operands");
+    }
+
+    return values.pop();
+  }
+
+  /**
+   * 对两个操作数执行指定运算.
+   *
+   * @param a        第一个操作数
+   * @param b        第二个操作数
+   * @param operator 要应用的运算符
+   * @return 运算结果
+   */
+  private static double performOperation(double a, double b, char operator) {
+    switch (operator) {
+      case '+':
+        return a + b;
+      case '-':
+        return a - b;
+      case '*':
+        return a * b;
+      case '/':
+        if (b == 0) {
+          throw new ArithmeticException("Division by zero");
+        }
+        return a / b;
+      case '^':
+        return Math.pow(a, b);
+      default:
+        throw new IllegalArgumentException("Unknown operator: " + operator);
+    }
+  }
+
+  private static double applyFunction(String function, double value) {
+    DoubleUnaryOperator operator = FUNCTIONS.get(function);
+    if (operator == null) {
+      throw new IllegalArgumentException("Unknown function: " + function);
+    }
+    return operator.applyAsDouble(value);
+  }
+
+  /**
+   * 检查记号是否为数字.
+   *
+   * @param token 待检查的记号
+   * @return 若为数字则返回 true，否则返回 false
+   */
+  private static boolean isNumber(String token) {
+    return NUMBER_PATTERN.matcher(token).matches();
+  }
+}

src/main/java/com/personalproject/service/MathLearningService.java

@@ -0,0 +1,180 @@
+package com.personalproject.service;
+
+import com.personalproject.auth.AccountRepository;
+import com.personalproject.auth.EmailService;
+import com.personalproject.auth.PasswordValidator;
+import com.personalproject.generator.QuestionGenerator;
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.model.ExamSession;
+import com.personalproject.storage.QuestionStorageService;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * 为主JavaFX UI提供所有功能的服务类. 此类协调各种服务以为UI提供统一的API.
+ */
+public final class MathLearningService {
+
+  private final AccountRepository accountRepository;
+  private final RegistrationService registrationService;
+  private final ExamService examService;
+  private final QuestionStorageService storageService;
+  private final ExamResultService resultService;
+
+  /**
+   * 创建一个新的数学学习服务.
+   *
+   * @param generatorMap              难度级别到题目生成器的映射
+   * @param questionGenerationService 题目生成服务
+   */
+  public MathLearningService(
+      Map<DifficultyLevel, QuestionGenerator> generatorMap,
+      QuestionGenerationService questionGenerationService) {
+    this.storageService = new QuestionStorageService();
+    this.accountRepository = new AccountRepository();
+    this.registrationService = new RegistrationService(accountRepository);
+    this.examService = new ExamService(generatorMap, questionGenerationService, storageService);
+    this.resultService = new ExamResultService();
+  }
+
+  // 注册方法
+
+  /**
+   * 通过向提供的电子邮件发送注册码来启动注册过程.
+   *
+   * @param username        所需用户名
+   * @param email           要发送注册码的电子邮件地址
+   * @param difficultyLevel 选择的难度级别
+   * @return 如果注册成功启动则返回true，如果电子邮件无效或用户名已存在则返回false
+   */
+  public boolean initiateRegistration(String username, String email,
+      DifficultyLevel difficultyLevel) {
+    return registrationService.initiateRegistration(username, email, difficultyLevel);
+  }
+
+  /**
+   * 验证用户输入的注册码.
+   *
+   * @param username         用户名
+   * @param registrationCode 通过电子邮件收到的注册码
+   * @return 如果注册码有效则返回true，否则返回false
+   */
+  public boolean verifyRegistrationCode(String username, String registrationCode) {
+    return registrationService.verifyRegistrationCode(username, registrationCode);
+  }
+
+  /**
+   * 在成功验证注册码后为用户设置密码.
+   *
+   * @param username 用户名
+   * @param password 要设置的密码
+   * @return 如果密码设置成功则返回true，如果验证失败或用户不存在则返回false
+   */
+  public boolean setPassword(String username, String password) {
+    return registrationService.setPassword(username, password);
+  }
+
+  /**
+   * 使用用户名和密码验证用户.
+   *
+   * @param username 用户名
+   * @param password 密码
+   * @return 如果验证成功则返回包含用户账户的Optional
+   */
+  public Optional<com.personalproject.auth.UserAccount> authenticate(String username,
+      String password) {
+    return registrationService.authenticate(username, password);
+  }
+
+  /**
+   * 检查密码是否符合验证要求.
+   *
+   * @param password 要验证的密码
+   * @return 如果密码有效则返回true，否则返回false
+   */
+  public static boolean isValidPassword(String password) {
+    return PasswordValidator.isValidPassword(password);
+  }
+
+  /**
+   * 更改现有用户的密码.
+   *
+   * @param username    用户名
+   * @param oldPassword 当前密码
+   * @param newPassword 新密码
+   * @return 如果密码更改成功则返回true，如果验证失败或验证失败则返回false
+   */
+  public boolean changePassword(String username, String oldPassword, String newPassword) {
+    return registrationService.changePassword(username, oldPassword, newPassword);
+  }
+
+  /**
+   * 检查电子邮件地址是否具有有效格式.
+   *
+   * @param email 要验证的电子邮件地址
+   * @return 如果电子邮件格式有效则返回true，否则返回false
+   */
+  public static boolean isValidEmail(String email) {
+    return EmailService.isValidEmail(email);
+  }
+
+  /**
+   * 为指定用户和难度级别创建新的考试会话.
+   *
+   * @param username        应试者用户名
+   * @param difficultyLevel 考试难度级别
+   * @param questionCount   考试中包含的题目数量
+   * @return 新的考试会话
+   */
+  public ExamSession createExamSession(String username, DifficultyLevel difficultyLevel,
+      int questionCount) {
+    return examService.createExamSession(username, difficultyLevel, questionCount);
+  }
+
+  /**
+   * 将考试结果保存到存储中.
+   *
+   * @param examSession 完成的考试会话
+   * @return 保存结果文件的路径
+   */
+  public java.nio.file.Path saveExamResults(ExamSession examSession) {
+    try {
+      return storageService.saveExamResults(examSession);
+    } catch (java.io.IOException e) {
+      throw new RuntimeException("保存考试结果失败", e);
+    }
+  }
+
+  /**
+   * 处理用户完成考试后的选择.
+   *
+   * @param examSession           完成的考试会话
+   * @param continueWithSameLevel 是否继续使用相同难度级别
+   * @param newDifficultyLevel    更改时的新难度级别（如果不更改则为null）
+   * @return 表示下一步操作的动作
+   */
+  public ExamResultService.ExamContinuationAction processExamResult(
+      ExamSession examSession, boolean continueWithSameLevel, DifficultyLevel newDifficultyLevel) {
+    return resultService.processExamResult(examSession, continueWithSameLevel, newDifficultyLevel);
+  }
+
+  /**
+   * 检查用户是否存在于系统中.
+   *
+   * @param username 要检查的用户名
+   * @return 如果用户存在则返回true，否则返回false
+   */
+  public boolean userExists(String username) {
+    return registrationService.userExists(username);
+  }
+
+  /**
+   * 按用户名获取用户账户.
+   *
+   * @param username 用户名
+   * @return 若找到则返回包含用户账户的 Optional
+   */
+  public Optional<com.personalproject.auth.UserAccount> getUser(String username) {
+    return registrationService.getUser(username);
+  }
+}

src/main/java/com/personalproject/service/QuestionGenerationService.java

@@ -0,0 +1,71 @@
+package com.personalproject.service;
+
+import com.personalproject.generator.QuestionGenerator;
+import com.personalproject.model.DifficultyLevel;
+import java.security.SecureRandom;
+import java.util.ArrayList;
+import java.util.EnumMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+
+/**
+ * 负责批量生成题目并避免与历史题库重复.
+ */
+public final class QuestionGenerationService {
+
+  private static final int MAX_ATTEMPTS = 10_000;
+  private final Map<DifficultyLevel, QuestionGenerator> generators;
+  private final Random random = new SecureRandom();
+
+  /**
+   * 构造函数：复制难度与生成器的映射，保留内部安全副本.
+   *
+   * @param generatorMap 难度到题目生成器的外部映射.
+   */
+  public QuestionGenerationService(Map<DifficultyLevel, QuestionGenerator> generatorMap) {
+    generators = new EnumMap<>(DifficultyLevel.class);
+    generators.putAll(generatorMap);
+  }
+
+  /**
+   * 根据指定难度批量生成不与历史题目重复的新题目.
+   *
+   * @param level             目标题目难度.
+   * @param count             需要生成的题目数量.
+   * @param existingQuestions 已存在的题目集合，用于查重.
+   * @return 生成的题目列表.
+   * @throws IllegalArgumentException 当难度未配置时抛出.
+   * @throws IllegalStateException    当达到最大尝试次数仍无法生成足够题目时抛出.
+   */
+  public List<String> generateUniqueQuestions(
+      DifficultyLevel level, int count, Set<String> existingQuestions) {
+    QuestionGenerator generator = generators.get(level);
+    if (generator == null) {
+      throw new IllegalArgumentException("Unsupported difficulty level: " + level);
+    }
+    Set<String> produced = new HashSet<>();
+    List<String> results = new ArrayList<>();
+    int attempts = 0;
+    while (results.size() < count) {
+      if (attempts >= MAX_ATTEMPTS) {
+        throw new IllegalStateException("Unable to generate enough unique questions.");
+      }
+      attempts++;
+      String question = generator.generateQuestion(random).trim();
+      if (question.isEmpty()) {
+        continue;
+      }
+      if (existingQuestions.contains(question)) {
+        continue;
+      }
+      if (!produced.add(question)) {
+        continue;
+      }
+      results.add(question);
+    }
+    return results;
+  }
+}

src/main/java/com/personalproject/service/RegistrationService.java

@@ -0,0 +1,201 @@
+package com.personalproject.service;
+
+import com.personalproject.auth.AccountRepository;
+import com.personalproject.auth.EmailService;
+import com.personalproject.auth.PasswordValidator;
+import com.personalproject.model.DifficultyLevel;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * 用于处理用户注册和身份验证过程的服务类.
+ */
+public final class RegistrationService {
+
+  private final AccountRepository accountRepository;
+  private final Map<String, String> pendingRegistrations;
+  private final Map<String, Integer> registrationAttempts;
+  private final Set<String> verifiedUsers;
+
+  /**
+   * 创建新的注册服务.
+   *
+   * @param accountRepository 使用的账户存储库
+   */
+  public RegistrationService(AccountRepository accountRepository) {
+    this.accountRepository = accountRepository;
+    this.pendingRegistrations = new ConcurrentHashMap<>();
+    this.registrationAttempts = new ConcurrentHashMap<>();
+    this.verifiedUsers = ConcurrentHashMap.newKeySet();
+  }
+
+  /**
+   * 通过向提供的电子邮件发送注册码来启动注册过程.
+   *
+   * @param username        所需用户名
+   * @param email           要发送注册码的电子邮件地址
+   * @param difficultyLevel 选择的难度级别
+   * @return 注册成功启动则返回true，如果电子邮件无效或用户名已存在则返回false
+   */
+  public boolean initiateRegistration(String username, String email,
+      DifficultyLevel difficultyLevel) {
+    if (username == null || email == null || difficultyLevel == null) {
+      return false;
+    }
+
+    String normalizedUsername = username.trim();
+    String normalizedEmail = email.trim();
+    if (normalizedUsername.isEmpty() || normalizedEmail.isEmpty()) {
+      return false;
+    }
+
+    if (!EmailService.isValidEmail(normalizedEmail)) {
+      return false;
+    }
+
+    if (!accountRepository.registerUser(normalizedUsername, normalizedEmail, difficultyLevel)) {
+      return false; // 用户名已存在或邮箱已注册
+    }
+
+    String registrationCode = EmailService.generateRegistrationCode();
+    pendingRegistrations.put(normalizedUsername, registrationCode);
+    registrationAttempts.put(normalizedUsername, 0);
+    verifiedUsers.remove(normalizedUsername);
+
+    boolean sent = EmailService.sendRegistrationCode(normalizedEmail, registrationCode);
+    if (!sent) {
+      pendingRegistrations.remove(normalizedUsername);
+      registrationAttempts.remove(normalizedUsername);
+      accountRepository.removeUnverifiedUser(normalizedUsername);
+    }
+    return sent;
+  }
+
+  /**
+   * 通过验证注册码完成注册.
+   *
+   * @param username         用户名
+   * @param registrationCode 通过电子邮件收到的注册码
+   * @return 注册码有效则返回true，否则返回false
+   */
+  public boolean verifyRegistrationCode(String username, String registrationCode) {
+    if (username == null || registrationCode == null) {
+      return false;
+    }
+    String normalizedUsername = username.trim();
+    String trimmedCode = registrationCode.trim();
+
+    String storedCode = pendingRegistrations.get(normalizedUsername);
+    if (storedCode == null || !storedCode.equals(trimmedCode)) {
+      // 跟踪失败尝试
+      int attempts = registrationAttempts.getOrDefault(normalizedUsername, 0);
+      attempts++;
+      registrationAttempts.put(normalizedUsername, attempts);
+
+      if (attempts >= 3) {
+        // 如果失败次数过多，则删除用户
+        pendingRegistrations.remove(normalizedUsername);
+        registrationAttempts.remove(normalizedUsername);
+        verifiedUsers.remove(normalizedUsername);
+        accountRepository.removeUnverifiedUser(normalizedUsername);
+        return false;
+      }
+      return false;
+    }
+
+    // 有效码，从待处理列表中移除
+    pendingRegistrations.remove(normalizedUsername);
+    registrationAttempts.remove(normalizedUsername);
+    verifiedUsers.add(normalizedUsername);
+    return true;
+  }
+
+  /**
+   * 在成功验证注册码后为用户设置密码.
+   *
+   * @param username 用户名
+   * @param password 要设置的密码
+   * @return 密码设置成功则返回true，如果验证失败或用户不存在则返回false
+   */
+  public boolean setPassword(String username, String password) {
+    if (username == null || password == null) {
+      return false;
+    }
+    String normalizedUsername = username.trim();
+    if (!PasswordValidator.isValidPassword(password)) {
+      return false;
+    }
+
+    if (!verifiedUsers.contains(normalizedUsername)) {
+      return false;
+    }
+
+    boolean updated = accountRepository.setPassword(normalizedUsername, password);
+    if (updated) {
+      verifiedUsers.remove(normalizedUsername);
+    }
+    return updated;
+  }
+
+  /**
+   * 更改现有用户的密码.
+   *
+   * @param username    用户名
+   * @param oldPassword 当前密码
+   * @param newPassword 新密码
+   * @return 密码更改成功则返回true，如果验证失败或身份验证失败则返回false
+   */
+  public boolean changePassword(String username, String oldPassword, String newPassword) {
+    if (username == null || oldPassword == null || newPassword == null) {
+      return false;
+    }
+    if (!PasswordValidator.isValidPassword(newPassword)) {
+      return false;
+    }
+
+    return accountRepository.changePassword(username.trim(), oldPassword, newPassword);
+  }
+
+  /**
+   * 使用用户名和密码验证用户.
+   *
+   * @param username 用户名
+   * @param password 密码
+   * @return 验证成功则返回包含用户账户的Optional
+   */
+  public Optional<com.personalproject.auth.UserAccount> authenticate(String username,
+      String password) {
+    if (username == null || password == null) {
+      return Optional.empty();
+    }
+    return accountRepository.authenticate(username.trim(), password);
+  }
+
+  /**
+   * 检查用户是否存在于系统中.
+   *
+   * @param username 要检查的用户名
+   * @return 用户存在则返回true，否则返回false
+   */
+  public boolean userExists(String username) {
+    if (username == null) {
+      return false;
+    }
+    return accountRepository.userExists(username.trim());
+  }
+
+  /**
+   * 按用户名获取用户账户.
+   *
+   * @param username 用户名
+   * @return 若找到则返回包含用户账户的 Optional
+   */
+  public Optional<com.personalproject.auth.UserAccount> getUser(String username) {
+    if (username == null) {
+      return Optional.empty();
+    }
+    return accountRepository.getUser(username.trim());
+  }
+}

src/main/java/com/personalproject/storage/QuestionStorageService.java

@@ -0,0 +1,150 @@
+package com.personalproject.storage;
+
+import com.personalproject.model.ExamSession;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Stream;
+
+/**
+ * 负责保存生成的题目并维护查重信息.
+ */
+public final class QuestionStorageService {
+
+  private static final String BASE_DIRECTORY = "user_data";
+  private static final String QUESTIONS_SUBDIR = "questions";
+  private static final String RESULTS_SUBDIR = "results";
+  private static final DateTimeFormatter FORMATTER =
+      DateTimeFormatter.ofPattern("yyyy-MM-dd-HH-mm-ss");
+
+  /**
+   * 加载指定用户历史生成的题目，用于后续查重.
+   *
+   * @param username 用户名.
+   * @return 历史题目的去重集合.
+   * @throws IOException 当读取文件时发生 I/O 错误.
+   */
+  public Set<String> loadExistingQuestions(String username) throws IOException {
+    Path accountDirectory = getQuestionsDirectory(username);
+    Set<String> questions = new HashSet<>();
+    if (!Files.exists(accountDirectory)) {
+      return questions;
+    }
+    try (Stream<Path> paths = Files.list(accountDirectory)) {
+      paths
+          .filter(path -> path.getFileName().toString().endsWith(".txt"))
+          .sorted()
+          .forEach(path -> readQuestionsFromFile(path, questions));
+    }
+    return questions;
+  }
+
+  /**
+   * 将新生成的题目保存到用户目录，并返回生成的文件路径.
+   *
+   * @param username  用户名.
+   * @param questions 待保存的题目列表.
+   * @return 保存题目的文件路径.
+   * @throws IOException 当写入文件失败时抛出.
+   */
+  public Path saveQuestions(String username, List<String> questions) throws IOException {
+    Path accountDirectory = getQuestionsDirectory(username);
+    Files.createDirectories(accountDirectory);
+    String fileName = FORMATTER.format(LocalDateTime.now()) + ".txt";
+    Path outputFile = accountDirectory.resolve(fileName);
+    StringBuilder builder = new StringBuilder();
+    for (int index = 0; index < questions.size(); index++) {
+      String question = questions.get(index);
+      builder
+          .append(index + 1)
+          .append(". ")
+          .append(question)
+          .append(System.lineSeparator())
+          .append(System.lineSeparator());
+    }
+    Files.writeString(
+        outputFile, builder.toString(), StandardCharsets.UTF_8, StandardOpenOption.CREATE_NEW);
+    return outputFile;
+  }
+
+  /**
+   * 保存用户的考试结果.
+   *
+   * @param examSession 包含结果的考试会话
+   * @return 保存结果文件的路径
+   * @throws IOException 如果写入文件失败
+   */
+  public Path saveExamResults(ExamSession examSession) throws IOException {
+    Path resultsDirectory = getResultsDirectory(examSession.getUsername());
+    Files.createDirectories(resultsDirectory);
+
+    StringBuilder builder = new StringBuilder();
+    builder.append("考试试卷").append(System.lineSeparator());
+    builder.append("用户名: ").append(examSession.getUsername()).append(System.lineSeparator());
+    builder.append("难度: ").append(examSession.getDifficultyLevel().getDisplayName())
+        .append(System.lineSeparator());
+    builder.append("开始时间: ").append(examSession.getStartTime()).append(System.lineSeparator());
+    builder.append("题目数量: ").append(examSession.getQuestions().size())
+        .append(System.lineSeparator());
+    builder.append(System.lineSeparator());
+
+    // 只保存题目内容
+    for (int i = 0; i < examSession.getQuestions().size(); i++) {
+      var question = examSession.getQuestions().get(i);
+      builder.append("题目 ").append(i + 1).append(": ").append(question.getQuestionText())
+          .append(System.lineSeparator());
+      builder.append(System.lineSeparator());
+    }
+
+    String fileName = "exam_result_" + FORMATTER.format(LocalDateTime.now()) + ".txt";
+    Path outputFile = resultsDirectory.resolve(fileName);
+
+    Files.writeString(
+        outputFile, builder.toString(), StandardCharsets.UTF_8, StandardOpenOption.CREATE_NEW);
+    return outputFile;
+  }
+
+  private Path getAccountDirectory(String username) {
+    return Paths.get(BASE_DIRECTORY, username);
+  }
+
+  private Path getQuestionsDirectory(String username) {
+    return getAccountDirectory(username).resolve(QUESTIONS_SUBDIR);
+  }
+
+  private Path getResultsDirectory(String username) {
+    return getAccountDirectory(username).resolve(RESULTS_SUBDIR);
+  }
+
+  private void readQuestionsFromFile(Path path, Set<String> questions) {
+    try {
+      List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
+      for (String line : lines) {
+        String trimmed = line.trim();
+        if (trimmed.isEmpty()) {
+          continue;
+        }
+        int dotIndex = trimmed.indexOf('.');
+        if (dotIndex >= 0 && dotIndex + 1 < trimmed.length()) {
+          String question = trimmed.substring(dotIndex + 1).trim();
+          if (!question.isEmpty()) {
+            questions.add(question);
+          }
+        } else {
+          questions.add(trimmed);
+        }
+      }
+    } catch (IOException exception) {
+      System.err.println(
+          "读取题目文件失败：" + path + "，原因：" + exception.getMessage() + "，将跳过该文件.");
+    }
+  }
+}

src/main/java/com/personalproject/ui/MathExamGui.java

@@ -0,0 +1,54 @@
+package com.personalproject.ui;
+
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.generator.HighSchoolQuestionGenerator;
+import com.personalproject.generator.MiddleSchoolQuestionGenerator;
+import com.personalproject.generator.PrimaryQuestionGenerator;
+import com.personalproject.generator.QuestionGenerator;
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.service.QuestionGenerationService;
+import com.personalproject.ui.scenes.LoginScene;
+import java.util.EnumMap;
+import java.util.Map;
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.stage.Stage;
+
+/**
+ * 数学学习软件的 JavaFX 图形界面应用程序. 这是图形界面的主要入口点.
+ */
+public final class MathExamGui extends Application {
+
+  private MathLearningController controller;
+
+  @Override
+  public void start(Stage primaryStage) {
+    // 使用题目生成器初始化控制器
+    Map<DifficultyLevel, QuestionGenerator> generatorMap = new EnumMap<>(DifficultyLevel.class);
+    generatorMap.put(DifficultyLevel.PRIMARY, new PrimaryQuestionGenerator());
+    generatorMap.put(DifficultyLevel.MIDDLE, new MiddleSchoolQuestionGenerator());
+    generatorMap.put(DifficultyLevel.HIGH, new HighSchoolQuestionGenerator());
+    QuestionGenerationService questionGenerationService = new QuestionGenerationService(
+        generatorMap);
+    this.controller = new MathLearningController(generatorMap, questionGenerationService);
+
+    // 配置主舞台
+    primaryStage.setTitle("数学学习软件");
+
+    // 从登录界面开始
+    LoginScene loginScene = new LoginScene(primaryStage, controller);
+    Scene scene = new Scene(loginScene, 600, 400);
+
+    primaryStage.setScene(scene);
+    primaryStage.show();
+  }
+
+  /**
+   * 启动 JavaFX 应用程序.
+   *
+   * @param args 命令行参数
+   */
+  public static void main(String[] args) {
+    launch(args);
+  }
+}

src/main/java/com/personalproject/ui/scenes/LoginScene.java

@@ -0,0 +1,162 @@
+package com.personalproject.ui.scenes;
+
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.ui.views.MainMenuView;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.control.TextField;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.GridPane;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 负责处理用户登录与注册的场景.
+ */
+public class LoginScene extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private TextField usernameField;
+  private PasswordField passwordField;
+  private Button loginButton;
+  private Button registerButton;
+
+  /**
+   * LoginScene 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   */
+  public LoginScene(Stage primaryStage, MathLearningController controller) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(15);
+    mainLayout.setAlignment(Pos.CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 标题
+    final Label titleLabel = new Label("数学学习软件");
+    titleLabel.setFont(Font.font("System", FontWeight.BOLD, 24));
+
+    // 登录表单
+    GridPane loginForm = new GridPane();
+    loginForm.setHgap(10);
+    loginForm.setVgap(10);
+    loginForm.setAlignment(Pos.CENTER);
+
+    final Label usernameLabel = new Label("用户名:");
+    usernameField = new TextField();
+    usernameField.setPrefWidth(200);
+
+    final Label passwordLabel = new Label("密码:");
+    passwordField = new PasswordField();
+    passwordField.setPrefWidth(200);
+
+    loginForm.add(usernameLabel, 0, 0);
+    loginForm.add(usernameField, 1, 0);
+    loginForm.add(passwordLabel, 0, 1);
+    loginForm.add(passwordField, 1, 1);
+
+    // 按钮
+    HBox buttonBox = new HBox(10);
+    buttonBox.setAlignment(Pos.CENTER);
+
+    loginButton = new Button("登录");
+    registerButton = new Button("注册");
+
+    // 设置按钮样式
+    loginButton.setPrefWidth(100);
+    registerButton.setPrefWidth(100);
+
+    buttonBox.getChildren().addAll(loginButton, registerButton);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(titleLabel, loginForm, buttonBox);
+
+    // 将主布局放到边界面板中央
+    setCenter(mainLayout);
+
+    // 添加事件处理器
+    addEventHandlers();
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers() {
+    loginButton.setOnAction(e -> handleLogin());
+    registerButton.setOnAction(e -> handleRegistration());
+
+    // 允许使用回车键登录
+    setOnKeyPressed(event -> {
+      if (event.getCode().toString().equals("ENTER")) {
+        handleLogin();
+      }
+    });
+  }
+
+  /**
+   * 处理登录流程.
+   */
+  private void handleLogin() {
+    String username = usernameField.getText().trim();
+    String password = passwordField.getText();
+
+    if (username.isEmpty() || password.isEmpty()) {
+      showAlert(Alert.AlertType.WARNING, "警告", "请输入用户名和密码");
+      return;
+    }
+
+    // 验证用户
+    var userAccount = controller.authenticate(username, password);
+
+    if (userAccount.isPresent()) {
+      // 登录成功，跳转到主菜单
+      MainMenuView mainMenuView = new MainMenuView(primaryStage, controller, userAccount.get());
+      primaryStage.getScene().setRoot(mainMenuView);
+    } else {
+      // 登录失败
+      showAlert(Alert.AlertType.ERROR, "登录失败", "用户名或密码错误");
+    }
+  }
+
+  /**
+   * 处理注册流程.
+   */
+  private void handleRegistration() {
+    // 切换到注册界面
+    RegistrationScene registrationScene = new RegistrationScene(primaryStage, controller);
+    primaryStage.getScene().setRoot(registrationScene);
+  }
+
+  /**
+   * 显示提示对话框.
+   *
+   * @param alertType 提示类型
+   * @param title     对话框标题
+   * @param message   显示的消息
+   */
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+}

src/main/java/com/personalproject/ui/scenes/RegistrationScene.java

@@ -0,0 +1,288 @@
+package com.personalproject.ui.scenes;
+
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.ui.views.MainMenuView;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.ComboBox;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.control.ScrollPane;
+import javafx.scene.control.TextField;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.GridPane;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 负责处理用户注册的场景.
+ */
+public class RegistrationScene extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private TextField usernameField;
+  private TextField emailField;
+  private ComboBox<DifficultyLevel> difficultyComboBox;
+  private Button sendCodeButton;
+  private TextField registrationCodeField;
+  private Button verifyCodeButton;
+  private PasswordField passwordField;
+  private PasswordField confirmPasswordField;
+  private Button setPasswordButton;
+  private Button backButton;
+  private VBox registrationForm;
+
+  /**
+   * RegistrationScene 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   */
+  public RegistrationScene(Stage primaryStage, MathLearningController controller) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(15);
+    mainLayout.setAlignment(Pos.TOP_CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 标题
+    final Label titleLabel = new Label("用户注册");
+    titleLabel.setFont(Font.font("System", FontWeight.BOLD, 24));
+
+    // 注册表单
+    registrationForm = new VBox(15);
+    registrationForm.setAlignment(Pos.CENTER);
+
+    // 步骤1：填写基础信息
+    GridPane basicInfoForm = new GridPane();
+    basicInfoForm.setHgap(10);
+    basicInfoForm.setVgap(10);
+    basicInfoForm.setAlignment(Pos.CENTER);
+
+    final Label usernameLabel = new Label("用户名:");
+    usernameField = new TextField();
+    usernameField.setPrefWidth(200);
+
+    final Label emailLabel = new Label("邮箱:");
+    emailField = new TextField();
+    emailField.setPrefWidth(200);
+
+    final Label difficultyLabel = new Label("默认难度:");
+    difficultyComboBox = new ComboBox<>();
+    difficultyComboBox.getItems()
+        .addAll(DifficultyLevel.PRIMARY, DifficultyLevel.MIDDLE, DifficultyLevel.HIGH);
+    difficultyComboBox.setValue(DifficultyLevel.PRIMARY);
+    difficultyComboBox.setPrefWidth(200);
+
+    basicInfoForm.add(usernameLabel, 0, 0);
+    basicInfoForm.add(usernameField, 1, 0);
+    basicInfoForm.add(emailLabel, 0, 1);
+    basicInfoForm.add(emailField, 1, 1);
+    basicInfoForm.add(difficultyLabel, 0, 2);
+    basicInfoForm.add(difficultyComboBox, 1, 2);
+
+    sendCodeButton = new Button("发送注册码");
+    sendCodeButton.setPrefWidth(120);
+
+    registrationForm.getChildren().addAll(basicInfoForm, sendCodeButton);
+
+    // 步骤2：验证码验证（初始隐藏）
+    VBox verificationSection = new VBox(10);
+    verificationSection.setAlignment(Pos.CENTER);
+    verificationSection.setVisible(false);
+    verificationSection.setManaged(false);
+
+    final Label codeLabel = new Label("注册码:");
+    registrationCodeField = new TextField();
+    registrationCodeField.setPrefWidth(200);
+
+    verifyCodeButton = new Button("验证注册码");
+    verifyCodeButton.setPrefWidth(120);
+
+    verificationSection.getChildren().addAll(codeLabel, registrationCodeField, verifyCodeButton);
+    registrationForm.getChildren().add(verificationSection);
+
+    // 步骤3：设置密码（初始隐藏）
+    VBox passwordSection = new VBox(10);
+    passwordSection.setAlignment(Pos.CENTER);
+    passwordSection.setVisible(false);
+    passwordSection.setManaged(false);
+
+    final Label passwordLabel = new Label("设置密码 (6-10位，包含大小写字母和数字):");
+    passwordField = new PasswordField();
+    passwordField.setPrefWidth(200);
+
+    final Label confirmPasswordLabel = new Label("确认密码:");
+    confirmPasswordField = new PasswordField();
+    confirmPasswordField.setPrefWidth(200);
+
+    setPasswordButton = new Button("设置密码");
+    setPasswordButton.setPrefWidth(120);
+
+    passwordSection.getChildren().addAll(passwordLabel, passwordField, confirmPasswordLabel,
+        confirmPasswordField, setPasswordButton);
+    registrationForm.getChildren().add(passwordSection);
+
+    // 返回按钮
+    backButton = new Button("返回");
+    backButton.setPrefWidth(100);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(titleLabel, registrationForm, backButton);
+
+    // 使用可滚动容器保证内容在小窗口中完整显示
+    ScrollPane scrollPane = new ScrollPane(mainLayout);
+    scrollPane.setFitToWidth(true);
+    scrollPane.setHbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
+    setCenter(scrollPane);
+
+    // 添加事件处理器
+    addEventHandlers(sendCodeButton, verificationSection, verifyCodeButton, passwordSection);
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers(Button sendCodeButton, VBox verificationSection,
+      Button verifyCodeButton, VBox passwordSection) {
+    sendCodeButton.setOnAction(e -> handleSendCode(verificationSection));
+    verifyCodeButton.setOnAction(e -> handleVerifyCode(passwordSection));
+    setPasswordButton.setOnAction(e -> handleSetPassword());
+    backButton.setOnAction(e -> handleBack());
+  }
+
+  /**
+   * 处理发送注册码的逻辑.
+   */
+  private void handleSendCode(VBox verificationSection) {
+    final String username = usernameField.getText().trim();
+    final String email = emailField.getText().trim();
+    final DifficultyLevel difficultyLevel = difficultyComboBox.getValue();
+
+    if (username.isEmpty() || email.isEmpty()) {
+      showAlert(Alert.AlertType.WARNING, "警告", "请输入用户名和邮箱");
+      return;
+    }
+
+    if (!controller.isValidEmail(email)) {
+      showAlert(Alert.AlertType.ERROR, "邮箱格式错误", "请输入有效的邮箱地址");
+      return;
+    }
+
+    // 发起注册
+    boolean success = controller.initiateRegistration(username, email, difficultyLevel);
+
+    if (success) {
+      showAlert(Alert.AlertType.INFORMATION, "注册码已发送", "注册码已发送至您的邮箱，请查收。");
+      verificationSection.setVisible(true);
+      verificationSection.setManaged(true);
+    } else {
+      showAlert(Alert.AlertType.ERROR, "注册失败", "用户名或邮箱可能已存在，请重试。");
+    }
+  }
+
+  /**
+   * 处理注册码验证.
+   */
+  private void handleVerifyCode(VBox passwordSection) {
+    final String username = usernameField.getText().trim();
+    final String registrationCode = registrationCodeField.getText().trim();
+
+    if (registrationCode.isEmpty()) {
+      showAlert(Alert.AlertType.WARNING, "警告", "请输入注册码");
+      return;
+    }
+
+    boolean verified = controller.verifyRegistrationCode(username, registrationCode);
+
+    if (verified) {
+      showAlert(Alert.AlertType.INFORMATION, "验证成功", "注册码验证成功！");
+      passwordSection.setVisible(true);
+      passwordSection.setManaged(true);
+    } else {
+      showAlert(Alert.AlertType.ERROR, "验证失败", "注册码验证失败，请检查后重试。");
+    }
+  }
+
+  /**
+   * 处理设置用户密码的逻辑.
+   */
+  private void handleSetPassword() {
+    final String username = usernameField.getText().trim();
+    final String password = passwordField.getText();
+    final String confirmPassword = confirmPasswordField.getText();
+
+    if (password.isEmpty() || confirmPassword.isEmpty()) {
+      showAlert(Alert.AlertType.WARNING, "警告", "请输入并确认密码");
+      return;
+    }
+
+    if (!password.equals(confirmPassword)) {
+      showAlert(Alert.AlertType.ERROR, "密码不匹配", "两次输入的密码不一致");
+      return;
+    }
+
+    if (!controller.isValidPassword(password)) {
+      showAlert(Alert.AlertType.ERROR, "密码不符合要求",
+          "密码长度必须为6-10位，且包含大小写字母和数字");
+      return;
+    }
+
+    boolean success = controller.setPassword(username, password);
+
+    if (success) {
+      var userAccountOptional = controller.getUserAccount(username);
+      if (userAccountOptional.isPresent()) {
+        showAlert(Alert.AlertType.INFORMATION, "注册成功", "注册成功！正在进入难度选择界面。");
+        MainMenuView mainMenuView = new MainMenuView(primaryStage, controller,
+            userAccountOptional.get());
+        if (primaryStage.getScene() != null) {
+          primaryStage.getScene().setRoot(mainMenuView);
+        }
+      } else {
+        showAlert(Alert.AlertType.WARNING, "注册提示",
+            "注册成功，但未能加载用户信息，请使用新密码登录。");
+        handleBack();
+      }
+    } else {
+      showAlert(Alert.AlertType.ERROR, "设置密码失败", "设置密码失败，请重试。");
+    }
+  }
+
+  /**
+   * 处理返回按钮的操作.
+   */
+  private void handleBack() {
+    LoginScene loginScene = new LoginScene(primaryStage, controller);
+    primaryStage.getScene().setRoot(loginScene);
+  }
+
+  /**
+   * 显示提示对话框.
+   *
+   * @param alertType 提示类型
+   * @param title     对话框标题
+   * @param message   显示的消息
+   */
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+}

src/main/java/com/personalproject/ui/views/ExamResultsView.java

@@ -0,0 +1,161 @@
+package com.personalproject.ui.views;
+
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.model.ExamSession;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 用于展示考试结果的界面.
+ */
+public class ExamResultsView extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private final ExamSession examSession;
+  private Button continueButton;
+  private Button exitButton;
+
+  /**
+   * ExamResultsView 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   * @param examSession  已完成的考试会话
+   */
+  public ExamResultsView(Stage primaryStage, MathLearningController controller,
+      ExamSession examSession) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    this.examSession = examSession;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(20);
+    mainLayout.setAlignment(Pos.CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 结果标题
+    Label titleLabel = new Label("考试结果");
+    titleLabel.setFont(Font.font("System", FontWeight.BOLD, 24));
+
+    // 分数展示
+    double score = examSession.calculateScore();
+    Label scoreLabel = new Label(String.format("您的得分: %.2f", score));
+    scoreLabel.setFont(Font.font("System", FontWeight.BOLD, 18));
+
+    // 成绩明细
+    VBox breakdownBox = new VBox(10);
+    breakdownBox.setAlignment(Pos.CENTER);
+
+    Label totalQuestionsLabel = new Label("总题数: " + examSession.getTotalQuestions());
+    Label correctAnswersLabel = new Label("答对题数: " + examSession.getCorrectAnswersCount());
+    Label incorrectAnswersLabel = new Label("答错题数: " + examSession.getIncorrectAnswersCount());
+
+    breakdownBox.getChildren()
+        .addAll(totalQuestionsLabel, correctAnswersLabel, incorrectAnswersLabel);
+
+    // 按钮区域
+    HBox buttonBox = new HBox(15);
+    buttonBox.setAlignment(Pos.CENTER);
+
+    continueButton = new Button("继续考试");
+    exitButton = new Button("退出");
+
+    // 设置按钮尺寸
+    continueButton.setPrefSize(120, 40);
+    exitButton.setPrefSize(120, 40);
+
+    buttonBox.getChildren().addAll(continueButton, exitButton);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(titleLabel, scoreLabel, breakdownBox, buttonBox);
+
+    // 将主布局置于边界面板中央
+    setCenter(mainLayout);
+
+    // 添加事件处理器
+    addEventHandlers();
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers() {
+    continueButton.setOnAction(e -> handleContinue());
+    exitButton.setOnAction(e -> handleExit());
+  }
+
+  /**
+   * 处理继续考试按钮的操作.
+   */
+  private void handleContinue() {
+    // 返回主菜单以开始新考试
+    controller.getUserAccount(examSession.getUsername())
+        .ifPresentOrElse(
+            userAccount -> {
+              MainMenuView mainMenuView = new MainMenuView(primaryStage, controller, userAccount);
+              primaryStage.getScene().setRoot(mainMenuView);
+            },
+            () -> {
+              // 如果找不到用户信息，则提示错误并返回登录界面
+              showAlert(Alert.AlertType.ERROR, "错误", "用户信息无法找到，请重新登录");
+              // 返回登录场景
+              com.personalproject.ui.scenes.LoginScene loginScene =
+                  new com.personalproject.ui.scenes.LoginScene(primaryStage, controller);
+              primaryStage.getScene().setRoot(loginScene);
+            }
+        );
+  }
+
+  /**
+   * 处理退出按钮的操作.
+   */
+  private void handleExit() {
+    // 返回主菜单
+    controller.getUserAccount(examSession.getUsername())
+        .ifPresentOrElse(
+            userAccount -> {
+              MainMenuView mainMenuView = new MainMenuView(primaryStage, controller, userAccount);
+              primaryStage.getScene().setRoot(mainMenuView);
+            },
+            () -> {
+              // 如果找不到用户信息，则提示错误并返回登录界面
+              showAlert(Alert.AlertType.ERROR, "错误", "用户信息无法找到，请重新登录");
+              // 返回登录场景
+              com.personalproject.ui.scenes.LoginScene loginScene =
+                  new com.personalproject.ui.scenes.LoginScene(primaryStage, controller);
+              primaryStage.getScene().setRoot(loginScene);
+            }
+        );
+  }
+
+  /**
+   * 显示提示对话框.
+   *
+   * @param alertType 提示类型
+   * @param title     对话框标题
+   * @param message   显示的消息
+   */
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+}

src/main/java/com/personalproject/ui/views/ExamSelectionView.java

@@ -0,0 +1,157 @@
+package com.personalproject.ui.views;
+
+import com.personalproject.auth.UserAccount;
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.model.DifficultyLevel;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.ComboBox;
+import javafx.scene.control.Label;
+import javafx.scene.control.Spinner;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.GridPane;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 用于选择考试难度和题目数量的界面.
+ */
+public class ExamSelectionView extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private final UserAccount userAccount;
+  private ComboBox<DifficultyLevel> difficultyComboBox;
+  private Spinner<Integer> questionCountSpinner;
+  private Button startExamButton;
+  private Button backButton;
+
+  /**
+   * ExamSelectionView 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   * @param userAccount  当前用户账户
+   */
+  public ExamSelectionView(Stage primaryStage, MathLearningController controller,
+      UserAccount userAccount) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    this.userAccount = userAccount;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(20);
+    mainLayout.setAlignment(Pos.CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 标题
+    final Label titleLabel = new Label("考试设置");
+    titleLabel.setFont(Font.font("System", FontWeight.BOLD, 24));
+
+    // 考试设置表单
+    GridPane examSettingsForm = new GridPane();
+    examSettingsForm.setHgap(15);
+    examSettingsForm.setVgap(15);
+    examSettingsForm.setAlignment(Pos.CENTER);
+
+    final Label difficultyLabel = new Label("选择难度:");
+    difficultyComboBox = new ComboBox<>();
+    difficultyComboBox.getItems()
+        .addAll(DifficultyLevel.PRIMARY, DifficultyLevel.MIDDLE, DifficultyLevel.HIGH);
+    difficultyComboBox.setValue(userAccount.difficultyLevel()); // 默认选中用户的难度
+    difficultyComboBox.setPrefWidth(200);
+
+    final Label questionCountLabel = new Label("题目数量 (10-30):");
+    questionCountSpinner = new Spinner<>(10, 30, 10); // 最小值、最大值、初始值
+    questionCountSpinner.setPrefWidth(200);
+
+    examSettingsForm.add(difficultyLabel, 0, 0);
+    examSettingsForm.add(difficultyComboBox, 1, 0);
+    examSettingsForm.add(questionCountLabel, 0, 1);
+    examSettingsForm.add(questionCountSpinner, 1, 1);
+
+    // 按钮区域
+    HBox buttonBox = new HBox(15);
+    buttonBox.setAlignment(Pos.CENTER);
+
+    startExamButton = new Button("开始考试");
+    backButton = new Button("返回");
+
+    // 设置按钮尺寸
+    startExamButton.setPrefSize(120, 40);
+    backButton.setPrefSize(120, 40);
+
+    buttonBox.getChildren().addAll(startExamButton, backButton);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(titleLabel, examSettingsForm, buttonBox);
+
+    // 将主布局置于边界面板中央
+    setCenter(mainLayout);
+
+    // 添加事件处理器
+    addEventHandlers();
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers() {
+    startExamButton.setOnAction(e -> handleStartExam());
+    backButton.setOnAction(e -> handleBack());
+  }
+
+  /**
+   * 处理开始考试按钮的操作.
+   */
+  private void handleStartExam() {
+    DifficultyLevel selectedDifficulty = difficultyComboBox.getValue();
+    int questionCount = questionCountSpinner.getValue();
+
+    if (questionCount < 10 || questionCount > 30) {
+      showAlert(Alert.AlertType.WARNING, "无效输入", "题目数量必须在10到30之间");
+      return;
+    }
+
+    // 创建并启动考试会话
+    com.personalproject.model.ExamSession examSession = controller.createExamSession(
+        userAccount.username(), selectedDifficulty, questionCount);
+
+    ExamView examView = new ExamView(primaryStage, controller, examSession);
+    primaryStage.getScene().setRoot(examView);
+  }
+
+  /**
+   * 处理返回按钮的操作.
+   */
+  private void handleBack() {
+    MainMenuView mainMenuView = new MainMenuView(primaryStage, controller, userAccount);
+    primaryStage.getScene().setRoot(mainMenuView);
+  }
+
+  /**
+   * 显示提示对话框.
+   *
+   * @param alertType 提示类型
+   * @param title     对话框标题
+   * @param message   显示的消息
+   */
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+}

src/main/java/com/personalproject/ui/views/ExamView.java

@@ -0,0 +1,267 @@
+package com.personalproject.ui.views;
+
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.model.ExamSession;
+import com.personalproject.model.QuizQuestion;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.control.RadioButton;
+import javafx.scene.control.ToggleGroup;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 提供答题界面以及题目与选项的呈现.
+ */
+public class ExamView extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private final ExamSession examSession;
+  private Label questionNumberLabel;
+  private Label questionTextLabel;
+  private ToggleGroup answerToggleGroup;
+  private VBox optionsBox;
+  private Button nextButton;
+  private Button previousButton;
+  private Button finishButton;
+  private HBox buttonBox;
+
+  /**
+   * ExamView 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   * @param examSession  当前的考试会话
+   */
+  public ExamView(Stage primaryStage, MathLearningController controller, ExamSession examSession) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    this.examSession = examSession;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(20);
+    mainLayout.setAlignment(Pos.CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 题号
+    questionNumberLabel = new Label();
+    questionNumberLabel.setFont(Font.font("System", FontWeight.BOLD, 16));
+
+    // 题目文本
+    questionTextLabel = new Label();
+    questionTextLabel.setWrapText(true);
+    questionTextLabel.setFont(Font.font("System", FontWeight.NORMAL, 14));
+    questionTextLabel.setMaxWidth(500);
+
+    // 选项容器
+    optionsBox = new VBox(10);
+    optionsBox.setPadding(new Insets(10));
+    answerToggleGroup = new ToggleGroup();
+
+    // 按钮区域
+    buttonBox = new HBox(15);
+    buttonBox.setAlignment(Pos.CENTER);
+
+    previousButton = new Button("上一题");
+    nextButton = new Button("下一题");
+    finishButton = new Button("完成考试");
+
+    // 设置按钮尺寸
+    previousButton.setPrefSize(100, 35);
+    nextButton.setPrefSize(100, 35);
+    finishButton.setPrefSize(120, 35);
+
+    buttonBox.getChildren().addAll(previousButton, nextButton, finishButton);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(questionNumberLabel, questionTextLabel, optionsBox, buttonBox);
+
+    // 将主布局置于边界面板中央
+    setCenter(mainLayout);
+
+    // 加载第一题
+    loadCurrentQuestion();
+
+    // 添加事件处理器
+    addEventHandlers();
+  }
+
+  /**
+   * 将当前题目加载到界面.
+   */
+  private void loadCurrentQuestion() {
+    try {
+      // 在加载下一题之前检查考试是否已完成
+      if (examSession.isComplete()) {
+        // 如果考试已完成，则启用“完成考试”按钮
+        updateButtonStates();
+        return;
+      }
+
+      QuizQuestion currentQuestion = examSession.getCurrentQuestion();
+      int currentIndex = examSession.getCurrentQuestionIndex();
+
+      if (currentQuestion == null) {
+        showAlert(Alert.AlertType.ERROR, "错误", "当前题目为空，请重新开始考试");
+        return;
+      }
+
+      // 更新题号与题目文本
+      questionNumberLabel.setText("第 " + (currentIndex + 1) + " 题");
+      questionTextLabel.setText(currentQuestion.getQuestionText());
+
+      // 清空上一题的选项
+      answerToggleGroup.selectToggle(null);
+      answerToggleGroup.getToggles().clear();
+      optionsBox.getChildren().clear();
+
+      // 创建新的选项组件
+      for (int i = 0; i < currentQuestion.getOptions().size(); i++) {
+        String option = currentQuestion.getOptions().get(i);
+        RadioButton optionButton = new RadioButton((i + 1) + ". " + option);
+        optionButton.setToggleGroup(answerToggleGroup);
+        optionButton.setUserData(i); // 存储选项索引
+
+        // 如果该题已有答案则自动选中
+        if (examSession.hasAnswered(currentIndex)
+            && examSession.getUserAnswer(currentIndex) == i) {
+          optionButton.setSelected(true);
+        }
+
+        optionsBox.getChildren().add(optionButton);
+      }
+
+      // 更新按钮状态
+      updateButtonStates();
+    } catch (Exception e) {
+      showAlert(Alert.AlertType.ERROR, "错误", "加载题目时发生错误: " + e.getMessage());
+    }
+  }
+
+  /**
+   * 根据当前位置更新导航按钮的状态.
+   */
+  private void updateButtonStates() {
+    try {
+      int currentIndex = examSession.getCurrentQuestionIndex();
+      int totalQuestions = examSession.getTotalQuestions();
+
+      // 处理潜在极端情况
+      if (totalQuestions <= 0) {
+        // 如果没有题目，则禁用所有导航按钮
+        previousButton.setDisable(true);
+        nextButton.setDisable(true);
+        finishButton.setDisable(false); // 仍允许完成考试
+        return;
+      }
+
+      // “上一题”按钮状态
+      previousButton.setDisable(currentIndex < 0 || currentIndex == 0);
+
+      // “下一题”按钮状态
+      nextButton.setDisable(currentIndex < 0 || currentIndex >= totalQuestions - 1);
+
+      // “完成考试”按钮状态——在考试完成或到达最后一题时启用
+      boolean isExamComplete = examSession.isComplete();
+      boolean isAtLastQuestion = (currentIndex >= totalQuestions - 1);
+      finishButton.setDisable(!(isExamComplete || isAtLastQuestion));
+    } catch (Exception e) {
+      // 若出现异常，禁用导航按钮以避免进一步问题
+      previousButton.setDisable(true);
+      nextButton.setDisable(true);
+      finishButton.setDisable(false); // 仍允许完成考试
+      showAlert(Alert.AlertType.ERROR, "错误", "更新按钮状态时发生错误: " + e.getMessage());
+    }
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers() {
+    nextButton.setOnAction(e -> handleNextQuestion());
+    previousButton.setOnAction(e -> handlePreviousQuestion());
+    finishButton.setOnAction(e -> handleFinishExam());
+
+    // 添加变更监听器，在选项被选择时保存答案
+    answerToggleGroup.selectedToggleProperty().addListener((obs, oldSelection, newSelection) -> {
+      if (newSelection != null) {
+        int selectedIndex = (Integer) newSelection.getUserData();
+        examSession.setAnswer(selectedIndex);
+      }
+    });
+  }
+
+  /**
+   * 处理“下一题”按钮的操作.
+   */
+  private void handleNextQuestion() {
+    try {
+      if (examSession.goToNextQuestion()) {
+        loadCurrentQuestion();
+      } else {
+        // 若无法跳转到下一题，可能已经到达末尾
+        // 检查考试是否完成并据此更新按钮状态
+        updateButtonStates();
+      }
+    } catch (Exception e) {
+      showAlert(Alert.AlertType.ERROR, "错误", "导航到下一题时发生错误: " + e.getMessage());
+    }
+  }
+
+  /**
+   * 处理“上一题”按钮的操作.
+   */
+  private void handlePreviousQuestion() {
+    try {
+      if (examSession.goToPreviousQuestion()) {
+        loadCurrentQuestion();
+      } else {
+        // 若无法返回上一题，可能已经位于开头
+        updateButtonStates();
+      }
+    } catch (Exception e) {
+      showAlert(Alert.AlertType.ERROR, "错误", "导航到上一题时发生错误: " + e.getMessage());
+    }
+  }
+
+  /**
+   * 显示提示对话框.
+   *
+   * @param alertType 提示类型
+   * @param title     对话框标题
+   * @param message   显示的消息
+   */
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+
+  /**
+   * 处理“完成考试”按钮的操作.
+   */
+  private void handleFinishExam() {
+    // 保存考试结果
+    controller.saveExamResults(examSession);
+
+    // 展示考试结果
+    ExamResultsView resultsView = new ExamResultsView(primaryStage, controller, examSession);
+    primaryStage.getScene().setRoot(resultsView);
+  }
+}

src/main/java/com/personalproject/ui/views/MainMenuView.java

@@ -0,0 +1,169 @@
+package com.personalproject.ui.views;
+
+import com.personalproject.auth.UserAccount;
+import com.personalproject.controller.MathLearningController;
+import com.personalproject.model.DifficultyLevel;
+import com.personalproject.ui.scenes.LoginScene;
+import java.util.Optional;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.control.TextInputDialog;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 用户可以开始考试或更改设置的主菜单界面.
+ */
+public class MainMenuView extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private final UserAccount userAccount;
+  private Button changePasswordButton;
+  private Button logoutButton;
+
+  /**
+   * MainMenuView 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   * @param userAccount  当前用户账户
+   */
+  public MainMenuView(Stage primaryStage, MathLearningController controller,
+      UserAccount userAccount) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    this.userAccount = userAccount;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(20);
+    mainLayout.setAlignment(Pos.CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 欢迎信息
+    Label welcomeLabel = new Label("欢迎, " + userAccount.username());
+    welcomeLabel.setFont(Font.font("System", FontWeight.BOLD, 18));
+
+    // 难度信息
+    Label difficultyLabel = new Label(
+        "当前难度: " + userAccount.difficultyLevel().getDisplayName());
+    difficultyLabel.setFont(Font.font("System", FontWeight.NORMAL, 14));
+
+    Label promptLabel = new Label("请选择考试难度开始答题");
+    promptLabel.setFont(Font.font("System", FontWeight.NORMAL, 14));
+
+    VBox difficultyBox = new VBox(10);
+    difficultyBox.setAlignment(Pos.CENTER);
+    difficultyBox.getChildren().addAll(
+        createDifficultyButton(DifficultyLevel.PRIMARY),
+        createDifficultyButton(DifficultyLevel.MIDDLE),
+        createDifficultyButton(DifficultyLevel.HIGH));
+
+    // 按钮区域
+    VBox buttonBox = new VBox(15);
+    buttonBox.setAlignment(Pos.CENTER);
+
+    changePasswordButton = new Button("修改密码");
+    logoutButton = new Button("退出登录");
+
+    // 设置按钮尺寸
+    changePasswordButton.setPrefSize(150, 40);
+    logoutButton.setPrefSize(150, 40);
+
+    buttonBox.getChildren().addAll(changePasswordButton, logoutButton);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(welcomeLabel, difficultyLabel, promptLabel, difficultyBox,
+        buttonBox);
+
+    // 将主布局置于边界面板中央
+    setCenter(mainLayout);
+
+    // 添加事件处理器
+    addEventHandlers();
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers() {
+    changePasswordButton.setOnAction(e -> handleChangePassword());
+    logoutButton.setOnAction(e -> handleLogout());
+  }
+
+  private Button createDifficultyButton(DifficultyLevel level) {
+    Button button = new Button(level.getDisplayName());
+    button.setPrefSize(150, 40);
+    button.setOnAction(e -> handleDifficultySelection(level));
+    return button;
+  }
+
+  private void handleDifficultySelection(DifficultyLevel level) {
+    TextInputDialog dialog = new TextInputDialog("10");
+    dialog.setTitle("题目数量");
+    dialog.setHeaderText("请选择题目数量");
+    dialog.setContentText("请输入题目数量 (10-30):");
+
+    Optional<String> result = dialog.showAndWait();
+    if (result.isEmpty()) {
+      return;
+    }
+
+    int questionCount;
+    try {
+      questionCount = Integer.parseInt(result.get().trim());
+    } catch (NumberFormatException ex) {
+      showAlert(Alert.AlertType.ERROR, "无效输入", "请输入有效的数字。");
+      return;
+    }
+
+    if (questionCount < 10 || questionCount > 30) {
+      showAlert(Alert.AlertType.WARNING, "题目数量范围错误", "题目数量必须在10到30之间。");
+      return;
+    }
+
+    com.personalproject.model.ExamSession examSession = controller.createExamSession(
+        userAccount.username(), level, questionCount);
+
+    ExamView examView = new ExamView(primaryStage, controller, examSession);
+    primaryStage.getScene().setRoot(examView);
+  }
+
+  /**
+   * 处理修改密码按钮的操作.
+   */
+  private void handleChangePassword() {
+    PasswordChangeView passwordChangeView = new PasswordChangeView(primaryStage, controller,
+        userAccount);
+    primaryStage.getScene().setRoot(passwordChangeView);
+  }
+
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+
+  /**
+   * 处理退出登录按钮的操作.
+   */
+  private void handleLogout() {
+    // 返回登录界面
+    LoginScene loginScene = new LoginScene(primaryStage, controller);
+    primaryStage.getScene().setRoot(loginScene);
+  }
+}

src/main/java/com/personalproject/ui/views/PasswordChangeView.java

@@ -0,0 +1,173 @@
+package com.personalproject.ui.views;
+
+import com.personalproject.auth.UserAccount;
+import com.personalproject.controller.MathLearningController;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.GridPane;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
+import javafx.scene.text.Font;
+import javafx.scene.text.FontWeight;
+import javafx.stage.Stage;
+
+/**
+ * 用户修改密码的界面.
+ */
+public class PasswordChangeView extends BorderPane {
+
+  private final Stage primaryStage;
+  private final MathLearningController controller;
+  private final UserAccount userAccount;
+  private PasswordField oldPasswordField;
+  private PasswordField newPasswordField;
+  private PasswordField confirmNewPasswordField;
+  private Button changePasswordButton;
+  private Button backButton;
+
+  /**
+   * PasswordChangeView 的构造函数.
+   *
+   * @param primaryStage 应用程序的主舞台
+   * @param controller   数学学习控制器
+   * @param userAccount  当前用户账户
+   */
+  public PasswordChangeView(Stage primaryStage, MathLearningController controller,
+      UserAccount userAccount) {
+    this.primaryStage = primaryStage;
+    this.controller = controller;
+    this.userAccount = userAccount;
+    initializeUi();
+  }
+
+  /**
+   * 初始化界面组件.
+   */
+  private void initializeUi() {
+    // 创建主布局
+    VBox mainLayout = new VBox(20);
+    mainLayout.setAlignment(Pos.CENTER);
+    mainLayout.setPadding(new Insets(20));
+
+    // 标题
+    final Label titleLabel = new Label("修改密码");
+    titleLabel.setFont(Font.font("System", FontWeight.BOLD, 24));
+
+    // 修改密码表单
+    GridPane passwordForm = new GridPane();
+    passwordForm.setHgap(15);
+    passwordForm.setVgap(15);
+    passwordForm.setAlignment(Pos.CENTER);
+
+    final Label oldPasswordLabel = new Label("当前密码:");
+    oldPasswordField = new PasswordField();
+    oldPasswordField.setPrefWidth(200);
+
+    final Label newPasswordLabel = new Label("新密码 (6-10位，包含大小写字母和数字):");
+    newPasswordField = new PasswordField();
+    newPasswordField.setPrefWidth(200);
+
+    final Label confirmNewPasswordLabel = new Label("确认新密码:");
+    confirmNewPasswordField = new PasswordField();
+    confirmNewPasswordField.setPrefWidth(200);
+
+    passwordForm.add(oldPasswordLabel, 0, 0);
+    passwordForm.add(oldPasswordField, 1, 0);
+    passwordForm.add(newPasswordLabel, 0, 1);
+    passwordForm.add(newPasswordField, 1, 1);
+    passwordForm.add(confirmNewPasswordLabel, 0, 2);
+    passwordForm.add(confirmNewPasswordField, 1, 2);
+
+    // 按钮区域
+    HBox buttonBox = new HBox(15);
+    buttonBox.setAlignment(Pos.CENTER);
+
+    changePasswordButton = new Button("修改密码");
+    backButton = new Button("返回");
+
+    // 设置按钮尺寸
+    changePasswordButton.setPrefSize(120, 40);
+    backButton.setPrefSize(120, 40);
+
+    buttonBox.getChildren().addAll(changePasswordButton, backButton);
+
+    // 将组件添加到主布局
+    mainLayout.getChildren().addAll(titleLabel, passwordForm, buttonBox);
+
+    // 将主布局置于边界面板中央
+    setCenter(mainLayout);
+
+    // 添加事件处理器
+    addEventHandlers();
+  }
+
+  /**
+   * 为界面组件添加事件处理器.
+   */
+  private void addEventHandlers() {
+    changePasswordButton.setOnAction(e -> handleChangePassword());
+    backButton.setOnAction(e -> handleBack());
+  }
+
+  /**
+   * 处理修改密码按钮的操作.
+   */
+  private void handleChangePassword() {
+    String oldPassword = oldPasswordField.getText();
+    String newPassword = newPasswordField.getText();
+    String confirmNewPassword = confirmNewPasswordField.getText();
+
+    if (oldPassword.isEmpty() || newPassword.isEmpty() || confirmNewPassword.isEmpty()) {
+      showAlert(Alert.AlertType.WARNING, "警告", "请填写所有字段");
+      return;
+    }
+
+    if (!newPassword.equals(confirmNewPassword)) {
+      showAlert(Alert.AlertType.ERROR, "密码不匹配", "新密码和确认密码不一致");
+      return;
+    }
+
+    if (!controller.isValidPassword(newPassword)) {
+      showAlert(Alert.AlertType.ERROR, "密码不符合要求",
+          "密码长度必须为6-10位，且包含大小写字母和数字");
+      return;
+    }
+
+    boolean success = controller.changePassword(userAccount.username(), oldPassword, newPassword);
+
+    if (success) {
+      showAlert(Alert.AlertType.INFORMATION, "修改成功", "密码修改成功！");
+      handleBack(); // 返回主菜单
+    } else {
+      showAlert(Alert.AlertType.ERROR, "修改失败", "当前密码错误或修改失败");
+    }
+  }
+
+  /**
+   * 处理返回按钮的操作.
+   */
+  private void handleBack() {
+    MainMenuView mainMenuView = new MainMenuView(primaryStage, controller, userAccount);
+    primaryStage.getScene().setRoot(mainMenuView);
+  }
+
+  /**
+   * 显示提示对话框.
+   *
+   * @param alertType 提示类型
+   * @param title     对话框标题
+   * @param message   显示的消息
+   */
+  private void showAlert(Alert.AlertType alertType, String title, String message) {
+    Alert alert = new Alert(alertType);
+    alert.setTitle(title);
+    alert.setHeaderText(null);
+    alert.setContentText(message);
+    alert.showAndWait();
+  }
+}

src/main/resources/email-config.properties

@@ -0,0 +1,20 @@
+
+# 主机不变
+mail.smtp.host=smtp.126.com
+
+# 关键修改：端口改为 465
+mail.smtp.port=465
+
+# 关键修改：禁用 STARTTLS
+mail.smtp.starttls.enable=false
+
+# 关键修改：启用 SSL
+mail.smtp.ssl.enable=true
+
+# 以下不变
+mail.smtp.auth=true
+mail.username=soloyouth@126.com
+mail.password=ZYsjxwDXFBsWeQcX
+mail.from=soloyouth@126.com
+mail.subject=数学学习软件注册验证码
+mail.debug=true