src/Main.java

@@ -0,0 +1,8 @@
+import ui.MainApplication;
+
+public class Main {
+    public static void main(String[] args) {
+        // R1: 启动图形化界面应用 (JavaFX)
+        MainApplication.launch(MainApplication.class, args);
+    }
+}

src/auth/AuthService.java

@@ -0,0 +1,206 @@
+package auth;
+
+import util.ModifyUtils;
+import util.EmailService;
+import java.io.*;
+import java.util.*;
+import java.util.regex.Pattern;
+
+public class AuthService {
+    private static final String USER_FILE_PATH = "user.txt";
+    private final EmailService emailService = new EmailService();
+    
+    
+ 
+    
+    public AuthService() {
+        // 检查用户文件是否存在
+        File userFile = new File(USER_FILE_PATH);
+        if (!userFile.exists()) {
+            System.err.println("用户文件不存在: " + USER_FILE_PATH);
+            try {
+                // 尝试创建文件
+                if (userFile.createNewFile()) {
+                    System.out.println("已创建用户文件: " + USER_FILE_PATH);
+                }
+            } catch (IOException e) {
+                System.err.println("创建用户文件失败: " + e.getMessage());
+            }
+        } 
+        
+    }
+    
+ 
+
+    // --- 校验和辅助方法 ---
+
+    private static final Pattern EMAIL_PATTERN =
+            Pattern.compile("^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,6}$");
+
+    // R3: 密码校验: 6-10 位, 必须含大小写字母和数字
+    public static boolean isPasswordValid(String password) {
+        if (password == null || password.length() < 6 ||
+                password.length() > 10) {
+            return false;
+        }
+        Pattern pattern =
+                Pattern.compile("^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d).{6,10}$");
+        return pattern.matcher(password).matches();
+    }
+
+    public boolean validateEmail(String email) {
+        if (email == null){
+            return false;
+        }
+        return EMAIL_PATTERN.matcher(email).matches();
+    }
+
+    // --- 用户加载和保存 ---
+
+    private User parseLine(String line, int lineNumber) {
+        line = line.trim();
+        if (line.isEmpty()) {
+            return null;
+        }
+
+        String[] parts = line.split("\\s+");
+        if (parts.length != 4) {
+            System.out.println("警告: 第" + lineNumber +
+                    "行数据格式不正确，需要4个数据。");
+            return null;
+        }
+        return new User(parts[0], parts[1], parts[2], parts[3]);
+    }
+
+    public List<User> loadUsers() {
+        List<User> users = new ArrayList<>();
+        int lineNumber = 1;
+        
+        try (BufferedReader br = new BufferedReader(new FileReader(USER_FILE_PATH))) {
+            String line;
+            while ((line = br.readLine()) != null) {
+                User user = parseLine(line, lineNumber);
+                if (user != null) {
+                    users.add(user);
+                }
+                lineNumber++;
+            }
+        } catch (IOException e) {
+            System.out.println("读取文件时发生错误: " + e.getMessage());
+        }
+
+        return users;
+    }
+
+    // --- 认证和注册 ---
+
+    public User login(String username, String password) {
+        List<User> users = loadUsers();
+        
+        for (User user : users) {
+            if ((user.getUsername().equals(username) || user.getEmail().equals(username)) &&
+                    user.getPassword().equals(password)) {
+                return user;
+            }
+        }
+        
+        return null;
+    }
+
+    public boolean isUsernameOrEmailTaken(String username, String email) {
+        List<User> users = loadUsers();
+        for (User user : users) {
+            if ((username != null && user.getUsername().equals(username)) ||
+                    (email != null && user.getEmail().equals(email))) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    // R2: 实际发送验证邮件
+    public String sendVerificationCode(String email) {
+        if (!validateEmail(email) || isUsernameOrEmailTaken(null, email)) {
+            return null;
+        }
+        String code = emailService.generateVerificationCode();
+        if (emailService.sendVerificationEmail(email, code)) {
+            return code;
+        }
+        return null;
+    }
+
+    private void writeUserData(String userData) throws IOException {
+        try (BufferedWriter writer =
+                     new BufferedWriter(new FileWriter(USER_FILE_PATH, true))) {
+            writer.write(userData);
+            writer.newLine();
+        }
+    }
+
+    // R2: 注册用户
+    public boolean registerUser(String username, String password, String email) {
+        if (isUsernameOrEmailTaken(username, email)) {
+            return false;
+        }
+
+        // 格式: username password type email
+        String userData = username + " " + password + " 小学 " + email;
+        try {
+            writeUserData(userData);
+            return true;
+        } catch (IOException e) {
+            System.out.println("写入文件时发生错误: " + e.getMessage());
+            return false;
+        }
+    }
+
+    // --- 用户修改 ---
+
+    public boolean updatePassword(String username, String newPassword) {
+        // 索引 1 是密码
+        int result = ModifyUtils.modifyFileField(USER_FILE_PATH, username, 1, newPassword);
+        return result != -1;
+    }
+
+    public boolean updateDifficulty(String username, String newDifficulty) {
+        List<String> lines = new ArrayList<>();
+        boolean found = false;
+        
+        try (BufferedReader br = new BufferedReader(new FileReader(USER_FILE_PATH))) {
+            String line;
+            while ((line = br.readLine()) != null) {
+                String[] parts = line.trim().split("\\s+");
+                
+                if (parts.length >= 4 && parts[0].equals(username)) {
+                    // 找到目标用户，更新难度
+                    parts[2] = newDifficulty;
+                    line = String.join(" ", parts);
+                    found = true;
+                }
+                lines.add(line);
+            }
+        } catch (IOException e) {
+            System.err.println("读取用户文件错误: " + e.getMessage());
+            return false;
+        }
+        
+        if (!found) {
+            System.err.println("未找到用户: " + username);
+            return false;
+        }
+        
+        // 写回文件
+        try (BufferedWriter bw = new BufferedWriter(new FileWriter(USER_FILE_PATH))) {
+            for (String line : lines) {
+                bw.write(line);
+                bw.newLine();
+            }
+            return true;
+        } catch (IOException e) {
+            System.err.println("写入用户文件错误: " + e.getMessage());
+            return false;
+        }
+    }
+    
+}

src/auth/User.java

@@ -0,0 +1,20 @@
+package auth;
+
+public class User {
+    private String username;
+    private String password;
+    private String type;
+    private String email;
+
+    public User(String username, String password, String type, String email) {
+        this.username = username;
+        this.password = password;
+        this.type = type;
+        this.email = email;
+    }
+
+    public String getUsername() { return username; }
+    public String getPassword() { return password; }
+    public String getType() { return type; }
+    public String getEmail() { return email; }
+}

src/auth/UserManager.java

@@ -0,0 +1,13 @@
+package auth;
+
+public class UserManager {
+    private final AuthService authService;
+
+    public UserManager() {
+        this.authService = new AuthService();
+    }
+
+    public User login(String username, String password) {
+        return authService.login(username, password);
+    }
+}

src/fxml/css/main.css

@@ -0,0 +1,170 @@
+/* 根容器样式 */
+.root {
+    -fx-font-family: "Microsoft YaHei", "Segoe UI", sans-serif;
+    -fx-background-image: url("1.jpg");
+    -fx-background-repeat: no-repeat;
+    -fx-background-size: cover;
+}
+
+/* 通用按钮样式 */
+.button {
+    -fx-background-color: #4CAF50;
+    -fx-text-fill: white;
+    -fx-font-size: 14px;
+    -fx-font-weight: bold;
+    -fx-padding: 10px 20px;
+    -fx-background-radius: 25px;
+    -fx-border-radius: 25px;
+    -fx-cursor: hand;
+    -fx-effect: dropshadow(three-pass-box, rgba(0,0,0,0.3), 5, 0, 0, 2);
+    -fx-transition: all 0.3s;
+}
+
+.button:hover {
+    -fx-background-color: #45a049;
+    -fx-scale-x: 1.05;
+    -fx-scale-y: 1.05;
+    -fx-effect: dropshadow(three-pass-box, rgba(0,0,0,0.5), 8, 0, 0, 3);
+}
+
+.button:pressed {
+    -fx-background-color: #3d8b40;
+    -fx-scale-x: 0.95;
+    -fx-scale-y: 0.95;
+}
+
+/* 次要按钮样式 */
+.button-secondary {
+    -fx-background-color: #2196F3;
+}
+
+.button-secondary:hover {
+    -fx-background-color: #1976D2;
+}
+
+.button-secondary:pressed {
+    -fx-background-color: #0D47A1;
+}
+
+/* 警告按钮样式 */
+.button-warning {
+    -fx-background-color: #ff9800;
+}
+
+.button-warning:hover {
+    -fx-background-color: #f57c00;
+}
+
+/* 危险按钮样式 */
+.button-danger {
+    -fx-background-color: #f44336;
+}
+
+.button-danger:hover {
+    -fx-background-color: #d32f2f;
+}
+
+/* 标签样式 */
+.label {
+    -fx-text-fill: #333333;
+    -fx-font-size: 14px;
+}
+
+.label-title {
+    -fx-font-size: 24px;
+    -fx-font-weight: bold;
+    -fx-text-fill: #2c3e50;
+    -fx-effect: dropshadow(three-pass-box, rgba(0,0,0,0.1), 3, 0, 1, 1);
+}
+
+.label-subtitle {
+    -fx-font-size: 18px;
+    -fx-font-weight: bold;
+    -fx-text-fill: #34495e;
+}
+
+.label-info {
+    -fx-text-fill: #7f8c8d;
+    -fx-font-size: 12px;
+}
+
+/* 输入框样式 */
+.text-field, .password-field {
+    -fx-background-color: white;
+    -fx-border-color: #bdc3c7;
+    -fx-border-radius: 15px;
+    -fx-background-radius: 15px;
+    -fx-padding: 10px 15px;
+    -fx-font-size: 14px;
+    -fx-effect: innershadow(three-pass-box, rgba(0,0,0,0.1), 5, 0, 0, 2);
+}
+
+.text-field:focused, .password-field:focused {
+    -fx-border-color: #3498db;
+    -fx-effect: dropshadow(three-pass-box, rgba(52, 152, 219, 0.3), 10, 0, 0, 3);
+}
+
+/* 下拉框样式 */
+.combo-box {
+    -fx-background-color: white;
+    -fx-border-color: #bdc3c7;
+    -fx-border-radius: 15px;
+    -fx-background-radius: 15px;
+    -fx-padding: 5px 15px;
+}
+
+.combo-box .arrow-button {
+    -fx-background-color: transparent;
+}
+
+.combo-box .list-cell {
+    -fx-background-color: white;
+    -fx-text-fill: #333333;
+}
+
+.combo-box .list-view {
+    -fx-background-color: white;
+    -fx-border-color: #bdc3c7;
+    -fx-border-radius: 10px;
+    -fx-background-radius: 10px;
+}
+
+/* 单选按钮样式 */
+.radio-button {
+    -fx-text-fill: #333333;
+    -fx-font-size: 14px;
+    -fx-padding: 5px;
+}
+
+.radio-button .radio {
+    -fx-background-color: white;
+    -fx-border-color: #bdc3c7;
+    -fx-border-radius: 50%;
+    -fx-background-radius: 50%;
+}
+
+.radio-button:selected .radio {
+    -fx-background-color: #3498db;
+    -fx-border-color: #2980b9;
+}
+
+.radio-button .dot {
+    -fx-background-color: white;
+    -fx-background-radius: 50%;
+}
+
+/* 容器样式 */
+.vbox {
+    -fx-background-color: rgba(255, 255, 255, 0.5); 
+    -fx-background-radius: 16px;
+}
+
+
+.container {
+    -fx-background-color: white;
+    -fx-background-radius: 20px;
+    -fx-border-radius: 20px;
+    -fx-effect: dropshadow(three-pass-box, rgba(0,0,0,0.1), 15, 0, 0, 5);
+    -fx-padding: 30px;
+}
+

src/fxml/difficulty-selection.fxml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.ComboBox?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Region?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.ExamController">
+   <children>
+      <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" minHeight="360.0" minWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="20.0" styleClass="vbox" stylesheets="@css/main.css">
+         <padding>
+            <Insets bottom="20.0" left="20.0" right="20.0" top="20.0" />
+         </padding>
+         <Label fx:id="titleLabel" style="-fx-font-size: 25; -fx-font-weight: bold;" text="难度" />
+         <HBox alignment="CENTER" prefHeight="65.0" prefWidth="241.0">
+            <children>
+               <ComboBox fx:id="difficultyCombo" prefHeight="37.0" prefWidth="99.0" promptText="难度" />
+               <Region prefHeight="65.0" prefWidth="31.0" /> 
+               <Button fx:id="switchDiffButton" onAction="#handleSwitchDifficulty" prefHeight="39.0" prefWidth="97.0" styleClass="button-warning" text="切换难度" />
+            </children>
+         </HBox>
+         <TextField fx:id="countField" alignment="CENTER" maxWidth="220.0" promptText="输入生成题目数量 (10-30)" />
+         <Button fx:id="startButton" onAction="#handleStartExam" styleClass="button-secondary" text="生成试卷" />
+         <Button fx:id="logoutButton" onAction="#handleLogout" styleClass="button-danger" text="退出登录" />
+         <VBox.margin>
+            <Insets left="30.0" />
+         </VBox.margin>
+      </VBox>
+   </children>
+</VBox>

src/fxml/exam-problem.fxml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Region?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" spacing="15" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.ExamController">
+   <VBox alignment="CENTER_LEFT" maxHeight="300.0" maxWidth="270.0" prefHeight="300.0" styleClass="vbox">
+      <children>
+         <Label fx:id="problemText" style="-fx-font-size: 12;">
+            <VBox.margin>
+               <Insets left="8.0" />
+            </VBox.margin>
+         </Label>
+         <Region prefHeight="17.0" prefWidth="300.0" />
+         <VBox fx:id="optionsBox" alignment="CENTER_LEFT" maxHeight="150.0" maxWidth="300.0" spacing="5" />
+         <HBox alignment="CENTER">
+            <children>
+               <Button fx:id="nextButton" onAction="#handleNextProblem" text="下一题" />
+            </children>
+         </HBox>
+      </children>
+      <VBox.margin>
+         <Insets left="30.0" />
+      </VBox.margin>
+   </VBox>
+</VBox>

src/fxml/login.fxml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.PasswordField?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Region?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.LoginController">
+   <children>
+      <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" minHeight="360.0" minWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="20.0" styleClass="vbox">
+         <Label style="-fx-font-size: 25; -fx-font-weight: bold;" text="登  录" />
+         <TextField fx:id="usernameField" maxWidth="220.0" promptText="用户名/邮箱" />
+         <PasswordField fx:id="passwordField" maxWidth="220.0" promptText="密码" />
+         <HBox alignment="CENTER" prefHeight="23.0" prefWidth="143.0">
+            <children>
+               <Button fx:id="loginButton" onAction="#handleLogin" styleClass="button-secondary" text="登录" />
+               <Region prefHeight="23.0" prefWidth="30.0" />
+               <Button fx:id="registerButton" onAction="#handleRegister" text="注册" />
+            </children>
+         </HBox>
+         <Button fx:id="modifyPasswordButton" onAction="#handleModifyPassword" styleClass="button-warning" text="修改密码" />
+         <Label fx:id="messageLabel" style="-fx-text-fill: red;" textAlignment="CENTER">
+            <VBox.margin>
+               <Insets />
+            </VBox.margin>
+         </Label>
+         <VBox.margin>
+            <Insets left="30.0" />
+         </VBox.margin>
+      </VBox>
+   </children>
+</VBox>

src/fxml/modify-password.fxml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.PasswordField?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Region?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" spacing="10" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.ModifyPasswordController">
+   <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" minHeight="360.0" minWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="12.0" styleClass="vbox">
+      <children>
+         <Label style="-fx-font-size: 25; -fx-font-weight: bold;" text="修改密码">
+            <VBox.margin>
+               <Insets top="8.0" />
+            </VBox.margin>
+         </Label>
+         <TextField fx:id="usernameField" alignment="CENTER" maxWidth="220.0" promptText="用户名" />
+         <PasswordField fx:id="oldPasswordField" alignment="CENTER" maxWidth="220.0" promptText="旧密码" />
+         <PasswordField fx:id="newPasswordField" alignment="CENTER" maxWidth="220.0" promptText="新密码" />
+         <PasswordField fx:id="confirmPasswordField" alignment="CENTER" maxWidth="220.0" promptText="确认新密码" />
+         <HBox alignment="CENTER" prefHeight="66.0" prefWidth="560.0">
+            <children>
+               <Button fx:id="backButton" onAction="#handleBack" styleClass="button-danger" text="返回登录" />
+               <Region prefHeight="45.0" prefWidth="33.0" />
+               <Button fx:id="modifyButton" onAction="#handleModifyPassword" styleClass="button-secondary" text="确认修改" />
+            </children>
+         </HBox>
+         <Label fx:id="messageLabel" style="-fx-text-fill: red;" />
+      </children>
+      <VBox.margin>
+         <Insets left="30.0" />
+      </VBox.margin>
+   </VBox>
+</VBox>

src/fxml/register-code.fxml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Region?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.RegisterController">
+   <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="30.0" styleClass="vbox">
+      <children>
+         <Label style="-fx-font-size: 24; -fx-font-weight: bold;" text="注册 (2/3) - 验证注册码">
+            <VBox.margin>
+               <Insets top="12.0" />
+            </VBox.margin>
+         </Label>
+         <Label fx:id="emailLabel" text="已发送到: " />
+         <TextField fx:id="codeField" alignment="CENTER" maxWidth="220.0" prefWidth="201.0" promptText="请输入收到的 6 位注册码" />
+         <Button fx:id="resendButton" onAction="#handleResendCode" prefHeight="39.0" prefWidth="96.0" text="重新发送" />
+         <HBox alignment="CENTER" prefHeight="58.0" prefWidth="560.0">
+            <children>
+               <Button fx:id="backButton" onAction="#handleBack" styleClass="button-danger" text="返回" />
+               <Region prefHeight="58.0" prefWidth="49.0" />
+               <Button fx:id="verifyButton" onAction="#handleVerifyCode" styleClass="button-secondary" text="验证" />
+            </children>
+         </HBox>
+         <Label fx:id="messageLabel" style="-fx-text-fill: red;" />
+      </children>
+      <VBox.margin>
+         <Insets left="30.0" />
+      </VBox.margin>
+   </VBox>
+</VBox>

src/fxml/register-email.fxml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.RegisterController">
+   <children>
+      <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="30.0" styleClass="vbox" stylesheets="@css/main.css">
+         <Label style="-fx-font-size: 25; -fx-font-weight: bold;" text="注册 (1/3) - 邮箱验证" />
+         <TextField fx:id="emailField" alignment="CENTER" maxWidth="220.0" promptText="邮箱" />
+         <Button fx:id="sendCodeButton" onAction="#handleSendCode" prefHeight="39.0" prefWidth="110.0" styleClass="button-secondary" text="发送注册码" />
+         <Button fx:id="backButton" onAction="#handleBack" styleClass="button-danger" text="返回" />
+         <Label fx:id="messageLabel" style="-fx-text-fill: red;" />
+         <VBox.margin>
+            <Insets left="30.0" />
+         </VBox.margin>
+      </VBox>
+   </children>
+</VBox>

src/fxml/register-password.fxml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.PasswordField?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.RegisterController">
+   <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" minHeight="360.0" minWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="15.0" styleClass="vbox">
+      <children>
+         <Label fx:id="titleLabel" style="-fx-font-size: 25; -fx-font-weight: bold;" text="注册 (3/3) - 设置密码" />
+         <TextField fx:id="usernameField" alignment="CENTER" maxWidth="220.0" promptText="设置用户名" />
+         <PasswordField fx:id="passwordField" alignment="CENTER" maxWidth="220.0" promptText="设置密码" />
+         <PasswordField fx:id="confirmPasswordField" alignment="CENTER" maxWidth="220.0" promptText="确认密码" />
+         <Button fx:id="completeButton" onAction="#handleCompleteRegistration" prefWidth="96.0" styleClass="button-secondary" text="完成注册" />
+         <Button fx:id="backButton" onAction="#handleBack" styleClass="button-danger" text="返回" />
+         <Label fx:id="messageLabel" style="-fx-text-fill: red;" />
+      </children>
+      <VBox.margin>
+         <Insets left="30.0" />
+      </VBox.margin>
+   </VBox>
+</VBox>

src/fxml/score-screen.fxml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.image.Image?>
+<?import javafx.scene.image.ImageView?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Region?>
+<?import javafx.scene.layout.VBox?>
+
+<VBox alignment="CENTER_LEFT" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/main.css" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ui.ExamController">
+   <VBox alignment="CENTER" maxHeight="360.0" maxWidth="270.0" minHeight="360.0" minWidth="270.0" prefHeight="360.0" prefWidth="270.0" spacing="20.0" styleClass="vbox">
+      <children>
+         <Label fx:id="scoreLabel" style="-fx-font-size: 25; -fx-font-weight: bold;" text="恭喜您完成答题！" />
+         <Label fx:id="finalScoreLabel" style="-fx-font-size: 15;" />
+         <ImageView fitHeight="70.0" fitWidth="130.0" pickOnBounds="true" preserveRatio="true">
+            <image>
+               <Image url="@css/2.gif" />
+            </image>
+         </ImageView>
+         <Button fx:id="continueButton" onAction="#handleContinue" prefHeight="39.0" prefWidth="218.0" styleClass="button-secondary" text="继续做题 (返回选择难度)" />
+         <HBox alignment="CENTER" prefHeight="0.0" prefWidth="270.0">
+            <children>
+               <Button fx:id="logoutButton" onAction="#handleLogout" styleClass="button-warning" text="退出登录" />
+               <Region prefHeight="39.0" prefWidth="28.0" />
+               <Button fx:id="exitButton" onAction="#handleExit" styleClass="button-danger" text="退出程序" />
+            </children>
+         </HBox>
+      </children>
+      <VBox.margin>
+         <Insets left="30.0" />
+      </VBox.margin>
+   </VBox>
+</VBox>

src/generator/HighGenerator.java

@@ -0,0 +1,28 @@
+package generator;
+
+import util.ExpressionUtils;
+import java.util.*;
+
+public class HighGenerator implements ProblemGenerator {
+    @Override
+    public List<Problem> generateProblems(int count) {
+        List<Problem> problems = new ArrayList<>();
+        int attempts = 0;
+        final int maxAttempts = count * 3; // 最多尝试3倍数量
+        
+        while (problems.size() < count && attempts < maxAttempts) {
+            Problem problem = ExpressionUtils.generateHighExpr();
+            if (problem != null) {
+                problems.add(problem);
+            }
+            attempts++;
+        }
+        
+        // 如果无法生成足够题目，用简单题目填充
+        while (problems.size() < count) {
+            problems.add(ExpressionUtils.createProblem("sin(30) + " + (problems.size() + 1)));
+        }
+        
+        return problems;
+    }
+}

src/generator/MiddleGenerator.java

@@ -0,0 +1,15 @@
+package generator;
+
+import util.ExpressionUtils;
+import java.util.*;
+
+public class MiddleGenerator implements ProblemGenerator {
+    @Override
+    public List<Problem> generateProblems(int count) {
+        List<Problem> problems = new ArrayList<>();
+        for (int i = 0; i < count; i++) {
+            problems.add(ExpressionUtils.generateMiddleExpr());
+        }
+        return problems;
+    }
+}

src/generator/PrimaryGenerator.java

@@ -0,0 +1,15 @@
+package generator;
+
+import util.ExpressionUtils;
+import java.util.*;
+
+public class PrimaryGenerator implements ProblemGenerator {
+    @Override
+    public List<Problem> generateProblems(int count) {
+        List<Problem> problems = new ArrayList<>(count);
+        for (int i = 0; i < count; i++) {
+            problems.add( ExpressionUtils.generatePrimaryExpr());
+        }
+        return problems;
+    }
+}

src/generator/Problem.java

@@ -0,0 +1,61 @@
+package generator;
+
+import java.util.List;
+import java.util.Collections;
+
+public class Problem {
+    private final String expression;
+    private final double result;
+    private final List<String> options;
+    private final String correctAnswerOption;
+
+    public Problem(String expression, double result, List<String> options,
+                   String correctAnswerOption) {
+        this.expression = expression;
+        this.result = result;
+        this.options = options;
+        this.correctAnswerOption = correctAnswerOption;
+    }
+
+    public String getQuestionText() {
+        return "计算: " + expression + " = ?";
+    }
+
+    public String getExpression() {
+        return expression;
+    }
+
+    public List<String> getOptions() {
+        return Collections.unmodifiableList(options);
+    }
+
+    public String getCorrectAnswerOption() {
+        return formatResult(result);
+    }
+    
+    private String formatResult(double result) {
+        if (Double.isNaN(result)) {
+            return "Error";
+        }
+        if (Math.abs(result - Math.round(result)) < 0.0001) {
+            return String.valueOf((int) Math.round(result));
+        }
+        return String.format("%.2f", result);
+    }
+
+    public double getResult() {
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append(getQuestionText()).append("\n");
+        char optionChar = 'A';
+        for (String option : options) {
+            sb.append(optionChar++).append(". ").append(option).append("  ");
+        }
+        sb.append("\n正确答案: ").append(correctAnswerOption);
+        return sb.toString();
+    }
+}

src/generator/ProblemGenerator.java

@@ -0,0 +1,7 @@
+package generator;
+
+import java.util.List;
+
+public interface ProblemGenerator {
+    List<Problem> generateProblems(int count);
+}

src/javafx-sdk-17.0.16/lib/javafx.properties

@@ -0,0 +1,3 @@
+javafx.version=17.0.16
+javafx.runtime.version=17.0.16+2
+javafx.runtime.build=2

src/run.bat

@@ -0,0 +1,78 @@
+@echo off
+chcp 65001 >nul
+setlocal enabledelayedexpansion
+
+:: 设置路径
+set JAVA_FX_PATH=javafx-sdk-17.0.16\lib
+set MAIL_JAR=referenced-lib\activation-1.1.1.jar
+set ACTIVATION_JAR=referenced-lib\javax.mail-1.6.2.jar
+
+:: 检查必要的 JAR 文件
+if not exist "%MAIL_JAR%" (
+    echo 错误: 找不到 %MAIL_JAR%
+    echo 请确保 JavaMail JAR 文件存在于 lib 文件夹中
+    pause
+    exit /b 1
+)
+
+if not exist "%ACTIVATION_JAR%" (
+    echo 警告: 找不到 %ACTIVATION_JAR%，尝试继续编译...
+)
+
+:: 清理并创建输出目录
+if exist out rmdir /s /q out
+mkdir out
+
+:: 构建类路径
+set CLASSPATH=%MAIL_JAR%
+if exist "%ACTIVATION_JAR%" set CLASSPATH=%CLASSPATH%;%ACTIVATION_JAR%
+
+echo 类路径: %CLASSPATH%
+echo.
+
+:: 编译项目
+echo 正在编译项目...
+javac -d out --module-path "%JAVA_FX_PATH%" --add-modules javafx.controls,javafx.fxml ^
+       -cp "referenced-lib\activation-1.1.1.jar;referenced-lib\javax.mail-1.6.2.jar" ^
+      auth\AuthService.java ^
+      auth\User.java ^
+      auth\UserManager.java ^
+      generator\HighGenerator.java ^
+      generator\MiddleGenerator.java ^
+      generator\PrimaryGenerator.java ^
+      generator\Problem.java ^
+      generator\ProblemGenerator.java ^
+      service\ExamService.java ^
+      ui\ExamController.java ^
+      ui\LoginController.java ^
+      ui\MainApplication.java ^
+      ui\ModifyPasswordController.java ^
+      ui\RegisterController.java ^
+      util\EmailService.java ^
+      util\ExpressionUtils.java ^
+      util\FileUtils.java ^
+      util\ModifyUtils.java ^
+      Main.java
+
+if !errorlevel! neq 0 (
+    echo.
+    echo 编译失败!
+    echo 请检查:
+    echo 1. JavaFX 路径是否正确: %JAVA_FX_PATH%
+    echo 2. JAR 文件是否存在: %CLASSPATH%
+    pause
+    exit /b 1
+)
+
+:: 复制资源文件
+echo 正在复制资源文件...
+xcopy fxml out\fxml /E /I /Y >nul 2>&1
+copy user.txt out\user.txt >nul 2>&1
+
+:: 运行项目
+echo 正在启动应用程序...
+java --module-path "%JAVA_FX_PATH%" ^
+     --add-modules javafx.controls,javafx.fxml ^
+     -cp "out;%CLASSPATH%" ^
+     -Dfile.encoding=UTF-8 ^
+     Main

src/service/ExamService.java

@@ -0,0 +1,109 @@
+package service;
+
+import auth.User;
+import generator.Problem;
+import generator.ProblemGenerator;
+import generator.PrimaryGenerator;
+import generator.MiddleGenerator;
+import generator.HighGenerator;
+import util.FileUtils;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+public class ExamService {
+
+    public ProblemGenerator getGenerator(String type) {
+        switch (type) {
+            case "小学": return new PrimaryGenerator();
+            case "初中": return new MiddleGenerator();
+            case "高中": return new HighGenerator();
+            default: return null;
+        }
+    }
+
+    private Problem generateUniqueProblem(ProblemGenerator generator,
+                                          Set<String> historyExpressions) {
+        int attempts = 0;
+        final int maxAttemptsPerProblem = 1000;
+
+        while (attempts < maxAttemptsPerProblem) {
+            Problem problem = generator.generateProblems(1).get(0);
+            // 查重基于题干 (表达式字符串)
+            if (!historyExpressions.contains(problem.getExpression())) {
+                historyExpressions.add(problem.getExpression());
+                return problem;
+            }
+            attempts++;
+        }
+        return null;
+    }
+
+    // R5: 生成一张唯一试卷，并将其保存到用户的历史记录中。
+    public List<Problem> generateExam(User currentUser, int count) {
+        if (count < 10 || count > 30) {
+            throw new IllegalArgumentException("题目数量必须在 10 到 30 之间");
+        }
+
+        ProblemGenerator generator = getGenerator(currentUser.getType());
+        if (generator == null) {
+            System.err.println("错误: 无法获取题目生成器，用户类型: " + currentUser.getType());
+            return new ArrayList<>();
+        }
+        
+        Set<String> historyExpressions = FileUtils.loadHistory(currentUser.getUsername());
+        List<Problem> problems = new ArrayList<>();
+
+        for(int i = 0; i < count; i++) {
+            Problem problem = generateUniqueProblem(generator, historyExpressions);
+            if (problem != null) {
+                problems.add(problem);
+            } else {
+                System.err.println("警告: 无法生成足够数量的唯一题目。已生成: " + problems.size() + " 题");
+                break;
+            }
+        }
+
+        if (!problems.isEmpty()) {
+            FileUtils.saveProblems(currentUser.getUsername(), problems);
+        } else {
+            System.err.println("错误: 未能生成任何题目");
+        }
+        
+        return problems;
+    }
+
+    // 将这个私有方法改为公共方法，以便在其他类中调用
+    public boolean isAnswerCorrect(Problem problem, String userAnswer) {
+        if (userAnswer == null || problem.getCorrectAnswerOption() == null) {
+            return false;
+        }
+        
+        boolean isCorrect = userAnswer.trim().equalsIgnoreCase(problem.getCorrectAnswerOption().trim());
+        return isCorrect;
+    }
+
+    // R6: 根据答对的百分比计算分数。
+    public int calculateScore(List<Problem> problems, List<String> answers) {
+        if (problems == null || answers == null || 
+            problems.size() != answers.size() || 
+            problems.isEmpty()) {
+            System.err.println("评分错误: 题目和答案数量不匹配");
+            return 0;
+        }
+
+        int correctCount = 0;
+        for (int i = 0; i < problems.size(); i++) {
+            Problem problem = problems.get(i);
+            String userAnswer = answers.get(i);
+            
+            if (isAnswerCorrect(problem, userAnswer)) {
+                correctCount++;
+            }
+        }
+
+        double score = ((double) correctCount / problems.size()) * 100;
+        int finalScore = (int) Math.round(score);
+        return finalScore;
+    }
+}

src/ui/ExamController.java

@@ -0,0 +1,442 @@
+package ui;
+
+import auth.User;
+import generator.Problem;
+import service.ExamService;
+import javafx.fxml.FXML;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.scene.control.*;
+import javafx.scene.layout.VBox;
+import javafx.stage.Stage;
+import auth.AuthService;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.HashMap;
+
+public class ExamController {
+
+    @FXML private Label titleLabel;
+    @FXML private ComboBox<String> difficultyCombo;
+    @FXML private TextField countField;
+    @FXML private Label problemText;
+    @FXML private VBox optionsBox;
+    @FXML private Button nextButton;
+    @FXML private Label scoreLabel;
+    @FXML private Label finalScoreLabel;
+
+    private Stage primaryStage;
+    private User currentUser;
+    private final ExamService examService = new ExamService();
+    private List<Problem> currentExam;
+    private List<String> userAnswers;
+    private int currentProblemIndex = 0;
+    private Map<Integer, Map<String, String>> optionMappings = new HashMap<>(); 
+
+    // 添加setter方法用于在界面间传递数据
+    public void setCurrentExam(List<Problem> currentExam) {
+        this.currentExam = currentExam;
+    }
+
+    public void setUserAnswers(List<String> userAnswers) {
+        this.userAnswers = userAnswers;
+    }
+    
+    @FXML
+    public void initialize() {
+        if (currentUser != null) {
+            System.out.println("当前用户: " + currentUser.getUsername() + ", 类型: " + currentUser.getType());
+        }
+    }
+    
+
+    public void setPrimaryStage(Stage primaryStage) {
+        this.primaryStage = primaryStage;
+    }
+
+    public void setCurrentUser(User user) {
+        this.currentUser = user;
+        initializeDifficultySelection();
+    }
+
+    private void initializeDifficultySelection() {
+        
+        if (titleLabel != null) {
+            titleLabel.setText("难度(当前: " + currentUser.getType() + ")");
+        }
+        
+        if (difficultyCombo != null) {
+            // 清空并重新添加选项
+            difficultyCombo.getItems().clear();
+            difficultyCombo.getItems().addAll("小学", "初中", "高中");
+            
+            // 设置当前用户类型为默认值
+            difficultyCombo.setValue(currentUser.getType());
+
+        } 
+    }
+
+    @FXML
+    private void handleSwitchDifficulty() {
+        
+        if (difficultyCombo == null) {
+            showAlert("错误", "界面初始化失败，请重新登录");
+            return;
+        }
+        
+        String newDifficulty = difficultyCombo.getValue();
+        
+        if (newDifficulty == null) {
+            showAlert("错误", "请先选择难度");
+            return;
+        }
+        
+        if (currentUser == null) {
+            System.err.println("错误: currentUser 为 null");
+            showAlert("错误", "用户信息丢失，请重新登录");
+            return;
+        }
+        
+        
+        if (newDifficulty.equals(currentUser.getType())) {
+            showAlert("提示", "已经是" + newDifficulty + "难度");
+            return;
+        }
+        
+        try {
+            // 创建 AuthService 实例
+            AuthService authService = new AuthService();
+            
+            // 更新数据库中的难度
+            boolean success = authService.updateDifficulty(currentUser.getUsername(), newDifficulty);
+            
+            if (success) {
+                // 验证更新是否成功 - 重新加载用户数据
+                User updatedUser = authService.login(currentUser.getUsername(), currentUser.getPassword());
+                
+                if (updatedUser != null) {
+                    currentUser = updatedUser;
+                    showAlert("成功", "难度已成功切换为: " + newDifficulty);
+                    
+                    // 更新界面显示
+                    if (titleLabel != null) {
+                        titleLabel.setText("难度选择 (当前: " + currentUser.getType() + ")");
+                    }
+                    
+                    // 重新初始化下拉框
+                    initializeDifficultySelection();
+                    
+                } else {
+                    System.err.println("错误: 重新加载用户信息失败");
+                    showAlert("错误", "用户信息验证失败");
+                }
+            } else {
+                System.err.println("错误: 文件更新失败");
+                showAlert("错误", "难度切换失败，请检查文件权限或联系管理员");
+            }
+        } catch (Exception e) {
+            System.err.println("难度切换异常: " + e.getMessage());
+            e.printStackTrace();
+            showAlert("错误", "难度切换异常: " + e.getMessage());
+        }
+        
+    }
+    
+    @FXML
+    private void handleStartExam() {
+        try {
+            int count = Integer.parseInt(countField.getText());
+            if (count < 10 || count > 30) {
+                throw new NumberFormatException();
+            }
+            generateAndShowExam(count);
+        } catch (NumberFormatException ex) {
+            showAlert("错误", "请输入有效的题目数量 (10-30)。");
+        } catch (Exception ex) {
+            showAlert("错误", "生成试卷失败: " + ex.getMessage());
+        }
+    }
+
+    @FXML
+    private void handleNextProblem() {
+        saveCurrentAnswer();
+        currentProblemIndex++;
+        if (currentProblemIndex < currentExam.size()) {
+            showProblem(currentProblemIndex);
+        } else {
+            showScoreScreen();
+        }
+    }
+
+    @FXML
+    private void handleContinue() {
+        showDifficultySelection();
+    }
+
+    @FXML
+    private void handleExit() {
+        primaryStage.close();
+    }
+
+    @FXML
+    private void handleLogout() {
+        showLoginScreen();
+    }
+
+    private void generateAndShowExam(int count) throws Exception {
+        currentExam = examService.generateExam(currentUser, count);
+        
+        // 检查试卷是否成功生成
+        if (currentExam == null || currentExam.isEmpty()) {
+            throw new Exception("无法生成试卷，请稍后重试");
+        }
+        
+        // 初始化所有数据结构
+        userAnswers = new ArrayList<>(currentExam.size());
+        optionMappings = new HashMap<>();
+        
+        for (int i = 0; i < currentExam.size(); i++) {
+            userAnswers.add(null);
+        }
+        
+        currentProblemIndex = 0;
+        showProblem(currentProblemIndex);
+    }
+
+    private void showProblem(int index) {
+        try {
+            // 检查索引是否有效
+            if (currentExam == null || index < 0 || index >= currentExam.size()) {
+                showAlert("错误", "题目索引无效，无法显示题目");
+                return;
+            }
+            
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/exam-problem.fxml"));
+            Parent root = loader.load();
+            
+            ExamController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            controller.setCurrentUser(currentUser);
+            controller.setCurrentExam(currentExam);
+            controller.setUserAnswers(userAnswers);
+            controller.setOptionMappings(optionMappings); // 传递选项映射
+            controller.setCurrentProblemIndex(index); // 设置当前题目索引
+            controller.displayProblem(currentExam.get(index), index);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载题目界面失败: " + e.getMessage());
+        }
+    }
+    
+    public void setOptionMappings(Map<Integer, Map<String, String>> optionMappings) {
+        this.optionMappings = optionMappings;
+    }
+
+    public void setCurrentProblemIndex(int currentProblemIndex) {
+        this.currentProblemIndex = currentProblemIndex;
+    }
+
+    // 修改 displayProblem 方法，确保每次都正确初始化
+    public void displayProblem(Problem problem, int index) {
+        // 确保当前索引正确设置
+        this.currentProblemIndex = index;
+        
+        // 确保 optionMappings 不为 null
+        if (optionMappings == null) {
+            optionMappings = new HashMap<>();
+        }
+        
+        if (problemText != null) {
+            problemText.setText((index + 1) + ". " + problem.getQuestionText());
+        }
+        
+        if (optionsBox != null) {
+            optionsBox.getChildren().clear();
+            ToggleGroup group = new ToggleGroup();
+            List<String> options = problem.getOptions();
+            char optionChar = 'A';
+
+            // 创建或更新当前题目的选项映射
+            Map<String, String> currentOptionMap = new HashMap<>();
+            optionMappings.put(index, currentOptionMap);
+
+            for (int i = 0; i < options.size(); i++) {
+                String optionLabel = String.valueOf(optionChar);
+                String optionValue = options.get(i);
+                currentOptionMap.put(optionLabel, optionValue);
+                
+                RadioButton rb = new RadioButton(optionLabel + ". " + optionValue);
+                rb.setUserData(optionLabel);  // 存储选项字母 A, B, C, D
+                rb.setToggleGroup(group);
+                rb.setStyle("-fx-font-size: 12px; -fx-font-weight: bold;");
+                optionsBox.getChildren().add(rb);
+
+                // 恢复选择 - 使用选项字母进行比较
+                if (userAnswers != null && index < userAnswers.size() && 
+                    userAnswers.get(index) != null && 
+                    userAnswers.get(index).equals(optionLabel)) {
+                    rb.setSelected(true);
+                }
+                optionChar++;
+            }
+        }
+
+        if (nextButton != null) {
+            nextButton.setText(index < currentExam.size() - 1 ? "下一题" : "提交并评分");
+        }
+        
+    }
+
+    private void saveCurrentAnswer() {
+        if (optionsBox == null || userAnswers == null || currentProblemIndex >= userAnswers.size()) {
+            return;
+        }
+        
+        // 查找选中的单选按钮
+        for (javafx.scene.Node node : optionsBox.getChildren()) {
+            if (node instanceof RadioButton) {
+                RadioButton rb = (RadioButton) node;
+                if (rb.isSelected()) {
+                    String selectedOption = (String) rb.getUserData();
+                    userAnswers.set(currentProblemIndex, selectedOption);
+                    return;
+                }
+            }
+        }
+        // 如果没有选择任何选项，设置为null
+        userAnswers.set(currentProblemIndex, null);
+    }
+
+    private void showScoreScreen() {
+        try {
+            // 保存最后一题的答案
+            saveCurrentAnswer();
+            
+            // 计算分数 - 使用新的评分方法
+            int score = calculateScore();
+            int correctCount = getCorrectCount();
+            
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/score-screen.fxml"));
+            Parent root = loader.load();
+            
+            ExamController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            controller.setCurrentUser(currentUser);
+            controller.displayScore(score, currentExam.size(), correctCount);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载评分界面失败: " + e.getMessage());
+        }
+    }
+    
+    // 添加计算正确数量的方法
+    private int getCorrectCount() {
+        int correctCount = 0;
+        for (int i = 0; i < currentExam.size(); i++) {
+            Problem problem = currentExam.get(i);
+            String userAnswerLetter = userAnswers.get(i);
+            
+            if (userAnswerLetter != null && optionMappings.containsKey(i)) {
+                String userSelectedValue = optionMappings.get(i).get(userAnswerLetter);
+                String correctAnswerValue = problem.getCorrectAnswerOption();
+                
+                if (userSelectedValue != null && userSelectedValue.equals(correctAnswerValue)) {
+                    correctCount++;
+                }
+            }
+        }
+        return correctCount;
+    }
+    
+    // 修改 displayScore 方法显示更详细的信息
+    public void displayScore(int score, int totalQuestions, int correctCount) {
+        if (finalScoreLabel != null) {
+            finalScoreLabel.setText(String.format("最终得分: %d / 100\n正确题数: %d / %d", 
+                score, correctCount, totalQuestions));
+        }
+    }
+
+    private void showDifficultySelection() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/difficulty-selection.fxml"));
+            Parent root = loader.load();
+            
+            ExamController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            controller.setCurrentUser(currentUser);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载难度选择界面失败: " + e.getMessage());
+        }
+    }
+
+    
+    private void showLoginScreen() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/Login.fxml"));
+            Parent root = loader.load();
+            
+            LoginController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载登录界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showAlert(String title, String message) {
+        Alert alert = new Alert(Alert.AlertType.INFORMATION);
+        alert.setTitle(title);
+        alert.setContentText(message);
+        alert.showAndWait();
+    }
+      
+    // 在 ExamController 中添加评分方法
+    private int calculateScore() {
+        if (currentExam == null || userAnswers == null || 
+            currentExam.size() != userAnswers.size()) {
+            System.err.println("评分错误: 数据不完整");
+            return 0;
+        }
+
+        int correctCount = 0;
+        for (int i = 0; i < currentExam.size(); i++) {
+            Problem problem = currentExam.get(i);
+            String userAnswerLetter = userAnswers.get(i);
+            if (userAnswerLetter != null && optionMappings != null && optionMappings.containsKey(i)) {
+                // 获取用户选择的选项对应的数值
+                String userSelectedValue = optionMappings.get(i).get(userAnswerLetter);
+                // 获取正确答案
+                String correctAnswerValue = problem.getCorrectAnswerOption();
+                
+                boolean isCorrect = userSelectedValue != null && 
+                                   userSelectedValue.equals(correctAnswerValue);
+                
+                if (isCorrect) {
+                    correctCount++;
+                }
+                
+            }
+        }
+
+        double score = ((double) correctCount / currentExam.size()) * 100;
+        int finalScore = (int) Math.round(score);
+        return finalScore;
+    }
+    
+}

src/ui/LoginController.java

@@ -0,0 +1,125 @@
+package ui;
+
+import auth.AuthService;
+import auth.User;
+import javafx.fxml.FXML;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.control.TextField;
+import javafx.stage.Stage;
+
+import java.io.IOException;
+
+public class LoginController {
+
+    @FXML private TextField usernameField;
+    @FXML private PasswordField passwordField;
+    @FXML private Label messageLabel;
+
+    private final AuthService authService = new AuthService();
+    private Stage primaryStage;
+
+    public void setPrimaryStage(Stage primaryStage) {
+        this.primaryStage = primaryStage;
+    }
+
+    @FXML
+    private void handleLogin() {
+        String username = usernameField.getText();
+        String password = passwordField.getText();
+        User user = authService.login(username, password);
+
+        if (user != null) {
+            messageLabel.setText("登录成功!");
+            showExamSelectScreen(user);
+        } else {
+            messageLabel.setText("登录失败，用户名或密码错误。");
+        }
+    }
+
+    @FXML
+    private void handleRegister() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/register-email.fxml"));
+            Parent root = loader.load();
+            
+            RegisterController controller = loader.getController();
+            
+            if (primaryStage != null) {
+                controller.setPrimaryStage(primaryStage);
+                Scene scene = new Scene(root);
+                primaryStage.setScene(scene);
+            } else {
+                Stage currentStage = (Stage) usernameField.getScene().getWindow();
+                controller.setPrimaryStage(currentStage);
+                Scene scene = new Scene(root);
+                currentStage.setScene(scene);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载注册界面失败: " + e.getMessage());
+        }
+    }
+
+    @FXML
+    private void handleModifyPassword() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/modify-password.fxml"));
+            Parent root = loader.load();
+            
+            ModifyPasswordController controller = loader.getController();
+            
+            // 确保primaryStage不为null
+            if (primaryStage != null) {
+                controller.setPrimaryStage(primaryStage);
+                Scene scene = new Scene(root);
+                primaryStage.setScene(scene);
+            } else {
+                // 备选方案：从当前场景获取stage
+                Stage currentStage = (Stage) usernameField.getScene().getWindow();
+                controller.setPrimaryStage(currentStage);
+                Scene scene = new Scene(root);
+                currentStage.setScene(scene);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载修改密码界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showExamSelectScreen(User user) {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/difficulty-selection.fxml"));
+            Parent root = loader.load();
+            
+            ExamController controller = loader.getController();
+            
+            if (primaryStage != null) {
+                controller.setPrimaryStage(primaryStage);
+                controller.setCurrentUser(user);
+                Scene scene = new Scene(root);
+                primaryStage.setScene(scene);
+            } else {
+                Stage currentStage = (Stage) usernameField.getScene().getWindow();
+                controller.setPrimaryStage(currentStage);
+                controller.setCurrentUser(user);
+                Scene scene = new Scene(root);
+                currentStage.setScene(scene);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载考试选择界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showAlert(String title, String message) {
+        Alert alert = new Alert(Alert.AlertType.ERROR);
+        alert.setTitle(title);
+        alert.setContentText(message);
+        alert.showAndWait();
+    }
+}

src/ui/MainApplication.java

@@ -0,0 +1,35 @@
+package ui;
+
+import javafx.application.Application;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.stage.Stage;
+import javafx.scene.image.Image;
+
+public class MainApplication extends Application {
+
+    @Override
+    public void start(Stage primaryStage) throws Exception {
+        FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/Login.fxml"));
+        Parent root = loader.load();
+        
+        // 获取控制器并设置primaryStage
+        LoginController controller = loader.getController();
+        controller.setPrimaryStage(primaryStage);
+        
+        Scene scene = new Scene(root);
+        
+       // 设置窗口图标
+        try {
+            Image icon = new Image(getClass().getResourceAsStream("/fxml/css/3.png"));
+            primaryStage.getIcons().add(icon);
+        } catch (Exception e) {
+            System.err.println("无法加载图标文件: " + e.getMessage());
+        }
+        
+        primaryStage.setTitle("小初高数学学习软件");
+        primaryStage.setScene(scene);
+        primaryStage.show();
+    }
+}

src/ui/ModifyPasswordController.java

@@ -0,0 +1,109 @@
+package ui;
+
+import auth.AuthService;
+import auth.User;
+import javafx.fxml.FXML;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.control.TextField;
+import javafx.stage.Stage;
+
+import java.io.IOException;
+
+public class ModifyPasswordController {
+
+    @FXML private TextField usernameField;
+    @FXML private PasswordField oldPasswordField;
+    @FXML private PasswordField newPasswordField;
+    @FXML private PasswordField confirmPasswordField;
+    @FXML private Label messageLabel;
+
+    private final AuthService authService = new AuthService();
+    private Stage primaryStage;
+
+    public void setPrimaryStage(Stage primaryStage) {
+        this.primaryStage = primaryStage;
+    }
+
+    @FXML
+    private void handleModifyPassword() {
+        String username = usernameField.getText().trim();
+        String oldPassword = oldPasswordField.getText();
+        String newPassword = newPasswordField.getText();
+        String confirmPassword = confirmPasswordField.getText();
+
+        User user = authService.login(username, oldPassword);
+        if (user == null) {
+            messageLabel.setText("错误：用户名或旧密码不正确。");
+            return;
+        }
+
+        if (!newPassword.equals(confirmPassword)) {
+            messageLabel.setText("错误：两次输入的新密码不一致。");
+            return;
+        }
+
+        if (!AuthService.isPasswordValid(newPassword)) {
+            messageLabel.setText("错误：新密码不符合要求 (6-10位, 需含大小写字母和数字)。");
+            return;
+        }
+
+        if (authService.updatePassword(username, newPassword)) {
+            showAlert("成功", "密码修改成功，请重新登录。");
+            showLoginScreen();
+        } else {
+            messageLabel.setText("错误：密码修改失败，请稍后重试。");
+        }
+    }
+
+    @FXML
+    private void handleBack() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/Login.fxml"));
+            Parent root = loader.load();
+            
+            LoginController controller = loader.getController();
+            
+            if (primaryStage != null) {
+                controller.setPrimaryStage(primaryStage);
+                Scene scene = new Scene(root);
+                primaryStage.setScene(scene);
+            } else {
+                Stage currentStage = (Stage) usernameField.getScene().getWindow();
+                controller.setPrimaryStage(currentStage);
+                Scene scene = new Scene(root);
+                currentStage.setScene(scene);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载登录界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showLoginScreen() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/Login.fxml"));
+            Parent root = loader.load();
+            
+            LoginController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载登录界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showAlert(String title, String message) {
+        Alert alert = new Alert(Alert.AlertType.INFORMATION);
+        alert.setTitle(title);
+        alert.setContentText(message);
+        alert.showAndWait();
+    }
+}

src/ui/RegisterController.java

@@ -0,0 +1,206 @@
+package ui;
+
+import auth.AuthService;
+import javafx.fxml.FXML;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.control.TextField;
+import javafx.stage.Stage;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+public class RegisterController {
+
+    @FXML private TextField emailField;
+    @FXML private TextField codeField;
+    @FXML private TextField usernameField;
+    @FXML private PasswordField passwordField;
+    @FXML private PasswordField confirmPasswordField;
+    @FXML private Label messageLabel;
+    @FXML private Label emailLabel;
+    @FXML private Label titleLabel;
+
+    private final AuthService authService = new AuthService();
+    private final Map<String, String> pendingRegistrations = new HashMap<>();
+    private Stage primaryStage;
+    private String currentEmail;
+
+    public void setPrimaryStage(Stage primaryStage) {
+        this.primaryStage = primaryStage;
+    }
+
+    @FXML
+    private void handleSendCode() {
+        String email = emailField.getText().trim();
+        if (!authService.validateEmail(email)) {
+            messageLabel.setText("错误：邮箱格式不正确。");
+            return;
+        }
+        if (authService.isUsernameOrEmailTaken(null, email)) {
+            messageLabel.setText("错误：该邮箱已被注册。");
+            return;
+        }
+
+        String code = authService.sendVerificationCode(email);
+        if (code != null) {
+            pendingRegistrations.put(email, code);
+            currentEmail = email;
+            showAlert("成功", "验证码已发送到您的邮箱，请查收！");
+            showRegisterCodeScreen();
+        } else {
+            messageLabel.setText("错误：验证码发送失败，请检查邮箱或服务器设置。");
+        }
+    }
+
+    @FXML
+    private void handleVerifyCode() {
+        String inputCode = codeField.getText().trim();
+        String storedCode = pendingRegistrations.get(currentEmail);
+
+        if (inputCode.equals(storedCode)) {
+            messageLabel.setText("验证成功！");
+            showRegisterPasswordScreen();
+        } else {
+            messageLabel.setText("错误：验证码不正确。");
+        }
+    }
+
+    @FXML
+    private void handleResendCode() {
+        String newCode = authService.sendVerificationCode(currentEmail);
+        if (newCode != null) {
+            pendingRegistrations.put(currentEmail, newCode);
+            messageLabel.setText("新的验证码已发送。");
+        } else {
+            messageLabel.setText("错误：重发失败。");
+        }
+    }
+
+    @FXML
+    private void handleCompleteRegistration() {
+        String username = usernameField.getText().trim();
+        String password = passwordField.getText();
+        String confirmPassword = confirmPasswordField.getText();
+
+        if (!validatePasswordSetup(username, password, confirmPassword)) {
+            return;
+        }
+
+        if (authService.registerUser(username, password, currentEmail)) {
+            pendingRegistrations.remove(currentEmail);
+            showAlert("成功", "注册成功，请登录。");
+            showLoginScreen();
+        } else {
+            messageLabel.setText("致命错误：注册失败，请联系管理员。");
+        }
+    }
+
+    @FXML
+    private void handleBack() {
+        showLoginScreen();
+    }
+
+    private boolean validatePasswordSetup(String username, String password, String confirmPassword) {
+        if (authService.isUsernameOrEmailTaken(username, null)) {
+            messageLabel.setText("错误：该用户名已被占用。");
+            return false;
+        }
+        if (!password.equals(confirmPassword)) {
+            messageLabel.setText("错误：两次密码输入不一致。");
+            return false;
+        }
+        if (!AuthService.isPasswordValid(password)) {
+            messageLabel.setText("错误：密码不符合要求 (6-10位, 需含大小写字母和数字)。");
+            return false;
+        }
+        return true;
+    }
+
+    private void showRegisterCodeScreen() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/register-code.fxml"));
+            Parent root = loader.load();
+            
+            RegisterController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            controller.setCurrentEmail(currentEmail);
+            controller.setPendingRegistrations(pendingRegistrations);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载验证码界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showRegisterPasswordScreen() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/register-password.fxml"));
+            Parent root = loader.load();
+            
+            RegisterController controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
+            controller.setCurrentEmail(currentEmail);
+            controller.setPendingRegistrations(pendingRegistrations);
+            
+            Scene scene = new Scene(root);
+            primaryStage.setScene(scene);
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载密码设置界面失败: " + e.getMessage());
+        }
+    }
+
+    private void showLoginScreen() {
+        try {
+            FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/Login.fxml"));
+            Parent root = loader.load();
+            
+            LoginController controller = loader.getController();
+            
+            if (primaryStage != null) {
+                controller.setPrimaryStage(primaryStage);
+                Scene scene = new Scene(root);
+                primaryStage.setScene(scene);
+            } else {
+                Stage currentStage = (Stage) emailField.getScene().getWindow();
+                controller.setPrimaryStage(currentStage);
+                Scene scene = new Scene(root);
+                currentStage.setScene(scene);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            showAlert("错误", "加载登录界面失败: " + e.getMessage());
+        }
+    }
+
+    // Setters for sharing data between different registration screens
+    public void setCurrentEmail(String email) {
+        this.currentEmail = email;
+        if (emailLabel != null) {
+            emailLabel.setText("已发送到: " + email);
+        }
+        if (titleLabel != null) {
+            titleLabel.setText("注册 (3/3) - 设置密码 (邮箱: " + email + ")");
+        }
+    }
+
+    public void setPendingRegistrations(Map<String, String> pendingRegistrations) {
+        this.pendingRegistrations.clear();
+        this.pendingRegistrations.putAll(pendingRegistrations);
+    }
+
+    private void showAlert(String title, String message) {
+        Alert alert = new Alert(Alert.AlertType.INFORMATION);
+        alert.setTitle(title);
+        alert.setContentText(message);
+        alert.showAndWait();
+    }
+}

src/util/EmailService.java

@@ -0,0 +1,69 @@
+package util;
+
+import java.util.Properties;
+import java.util.Random;
+import javax.mail.*;
+import javax.mail.internet.InternetAddress;
+import javax.mail.internet.MimeMessage;
+
+public class EmailService {
+    // 邮件配置：请修改此处或设置环境变量
+    private static final String SENDER_EMAIL = "2810672597@qq.com";
+    private static final String SENDER_PASSWORD =("acyhhpwgcqkqdgff");
+    private static final String SMTP_HOST = "smtp.qq.com"; // 例如: smtp.gmail.com
+    private static final String SMTP_PORT = "587"; // 或 465 (SSL)
+    private static final String SUBJECT = "数学学习软件注册验证码";
+
+    public String generateVerificationCode() {
+        Random rand = new Random();
+        return String.format("%06d", rand.nextInt(1000000));
+    }
+
+    private Properties getMailProperties() {
+        Properties props = new Properties();
+        props.put("mail.smtp.auth", "true");
+        props.put("mail.smtp.starttls.enable", "true");
+        props.put("mail.smtp.host", SMTP_HOST);
+        props.put("mail.smtp.port", SMTP_PORT);
+        return props;
+    }
+
+    private Message createMessage(Session session, String recipientEmail,
+                                  String code) throws MessagingException {
+        Message message = new MimeMessage(session);
+        message.setFrom(new InternetAddress(SENDER_EMAIL));
+        message.setRecipients(
+                Message.RecipientType.TO,
+                InternetAddress.parse(recipientEmail)
+        );
+        message.setSubject(SUBJECT);
+        message.setText("您的注册验证码是: " + code +
+                "\n\n请在应用中输入此代码完成注册。");
+        return message;
+    }
+
+    // R2: 实际发送验证邮件
+    public boolean sendVerificationEmail(String recipientEmail, String code) {
+        if (SENDER_EMAIL == null || SENDER_PASSWORD == null) {
+            System.err.println("错误: 邮件发送凭证未设置。");
+            return false;
+        }
+
+        Session session = Session.getInstance(getMailProperties(), new Authenticator() {
+            @Override
+            protected PasswordAuthentication getPasswordAuthentication() {
+                return new PasswordAuthentication(SENDER_EMAIL, SENDER_PASSWORD);
+            }
+        });
+
+        try {
+            Message message = createMessage(session, recipientEmail, code);
+            Transport.send(message);
+            return true;
+
+        } catch (MessagingException e) {
+            System.err.println("邮件发送失败: " + e.getMessage());
+            return false;
+        }
+    }
+}

src/util/ExpressionUtils.java

@@ -0,0 +1,358 @@
+package util;
+
+import generator.Problem;
+
+import java.util.*;
+
+public class ExpressionUtils {
+    private static Random rand = new Random();
+
+    private static final String[] OPS_PRIMARY = {"+", "-", "*", "/"};
+    private static final String[] OPS_MIDDLE = {"+", "-", "*", "/"};
+    //private static final String[] OPS_HIGH = {"+", "-", "*", "/", "^2", "sqrt"};
+
+
+    public static String randomNumber() {
+        return String.valueOf(rand.nextInt(100) + 1);
+    }
+
+    // --- 表达式求解和选项生成辅助方法 ---
+
+    public static double solveExpression(String expr) {
+    	// 预处理表达式，确保格式正确
+        String parsableExpr = expr
+            .replaceAll("(\\d+|\\([^)]+\\))\\^2", "pow($1, 2)")  // 处理平方
+            .replaceAll("sqrt\\s+(\\d+)", "sqrt($1)")  // 处理缺少括号的sqrt
+            .replaceAll("\\s+", " ");  // 标准化空格
+
+        try {
+            return new Object() {
+                int pos = -1, ch;
+
+                void nextChar() {
+                    ch = (++pos < parsableExpr.length()) ? parsableExpr.charAt(pos) : -1;
+                }
+
+                boolean eat(int charToEat) {
+                    while (ch == ' ') nextChar();
+                    if (ch == charToEat) {
+                        nextChar();
+                        return true;
+                    }
+                    return false;
+                }
+
+                double parse() {
+                    nextChar();
+                    double x = parseExpression();
+                    if (pos < parsableExpr.length()) throw new RuntimeException("Unexpected: " + (char) ch);
+                    return x;
+                }
+
+                double parseExpression() {
+                    double x = parseTerm();
+                    for (; ; ) {
+                        if (eat('+')) x += parseTerm(); // addition
+                        else if (eat('-')) x -= parseTerm(); // subtraction
+                        else return x;
+                    }
+                }
+
+                double parseTerm() {
+                    double x = parseFactor();
+                    for (; ; ) {
+                        if (eat('*')) x *= parseFactor(); // multiplication
+                        else if (eat('/')) { // division
+                            double divisor = parseFactor();
+                            if (divisor == 0) throw new ArithmeticException("Division by zero");
+                            x /= divisor;
+                        } else return x;
+                    }
+                }
+
+                double parseFactor() {
+                    if (eat('+')) return parseFactor(); // unary plus
+                    if (eat('-')) return -parseFactor(); // unary minus
+
+                    double x;
+                    int startPos = this.pos;
+                    if (eat('(')) { // parentheses
+                        x = parseExpression();
+                        eat(')');
+                    } else if ((ch >= '0' && ch <= '9') || ch == '.') { // numbers
+                        while ((ch >= '0' && ch <= '9') || ch == '.') nextChar();
+                        x = Double.parseDouble(parsableExpr.substring(startPos, this.pos));
+                    } else if (ch >= 'a' && ch <= 'z') { // functions
+                        while (ch >= 'a' && ch <= 'z') nextChar();
+                        String func = parsableExpr.substring(startPos, this.pos);
+                        x = parseFactor();
+                        switch (func) {
+                            case "sqrt":
+                                x = Math.sqrt(x);
+                                break;
+                            case "sin":
+                                x = Math.sin(Math.toRadians(x));
+                                break;
+                            case "cos":
+                                x = Math.cos(Math.toRadians(x));
+                                break;
+                            case "tan":
+                                x = Math.tan(Math.toRadians(x));
+                                break;
+                            case "pow":
+                                eat(',');
+                                double y = parseExpression();
+                                x = Math.pow(x, y);
+                                eat(')');
+                                break;
+                            default:
+                                throw new RuntimeException("Unknown function: " + func);
+                        }
+                    } else {
+                        throw new RuntimeException("Unexpected: " + (char) ch);
+                    }
+
+                    return x;
+                }
+            }.parse();
+        } catch (Exception e) {
+        	System.err.println("Error parsing expression: '" + expr + "'. Parsable version: '" + parsableExpr + "'. Error: " + e.getMessage());
+            return Double.NaN;
+        }
+    }
+
+
+    private static String formatResult(double result) {
+        if (Double.isNaN(result)) {
+            return "Error";
+        }
+        if (Math.abs(result - Math.round(result)) < 0.0001) {
+            return String.valueOf((int) Math.round(result));
+        }
+        return String.format("%.2f", result);
+    }
+
+    /**
+     * MODIFICATION: 确保为整数答案生成整数干扰项
+     */
+    private static String generateDistractor(double correctResult, List<String> existingOptions) {
+        if (Double.isNaN(correctResult)) {
+            return String.valueOf(rand.nextInt(100));
+        }
+
+        // 检查正确答案是否为整数
+        boolean isIntegerResult = Math.abs(correctResult - Math.round(correctResult)) < 0.0001;
+
+        double distractor;
+        String distractorStr;
+
+        do {
+            if (isIntegerResult) {
+                // 生成一个整数干扰项
+                int offset = rand.nextInt(20) + 1; // 扩大随机范围以避免重复
+                distractor = rand.nextBoolean() ? Math.round(correctResult) + offset : Math.round(correctResult) - offset;
+                // 确保干扰项不为负数
+                if (distractor < 0) {
+                    distractor = Math.round(correctResult) + offset;
+                }
+            } else {
+                // 答案是小数，则生成小数干扰项
+                distractor = correctResult +
+                        (rand.nextInt(10) + 1) * (rand.nextBoolean() ? 1 : -1) +
+                        (rand.nextDouble() * 0.9);
+            }
+            distractorStr = formatResult(distractor);
+        } while (existingOptions.contains(distractorStr)); // 确保选项不重复
+        return distractorStr;
+    }
+
+
+    public static List<String> generateOptions(double correctResult) {
+        List<String> options = new ArrayList<>();
+        options.add(formatResult(correctResult));
+
+        for (int i = 0; i < 3; i++) {
+            options.add(generateDistractor(correctResult, options));
+        }
+
+        Collections.shuffle(options);
+        return options;
+    }
+
+    public static Problem createProblem(String expression) {
+        double result = solveExpression(expression);
+        
+        // 如果解析失败，返回null，让调用者重新生成
+        if (Double.isNaN(result)) {
+            return null;
+        }
+        
+        String correctAnswerOption = formatResult(result);
+        List<String> options = generateOptions(result);
+        return new Problem(expression, result, options, correctAnswerOption);
+    }
+
+    // --- 题目生成方法 ---
+
+    private static int getDivisor(int dividend) {
+        List<Integer> divisors = new ArrayList<>();
+        for (int j = 1; j <= dividend; j++) {
+            if (dividend % j == 0) {
+                divisors.add(j);
+            }
+        }
+        return divisors.get(rand.nextInt(divisors.size()));
+    }
+
+    /**
+     * MODIFICATION: 增加答案非负、括号数量和操作数关联的逻辑
+     */
+    public static Problem generatePrimaryExpr() {
+        Problem problem;
+        double result;
+
+        do {
+            // 生成 2 到 4 个操作数
+            int operands = rand.nextInt(3) + 2;
+            List<String> parts = new ArrayList<>();
+
+            for (int i = 0; i < operands; i++) {
+                if (i > 0) {
+                    parts.add(OPS_PRIMARY[rand.nextInt(OPS_PRIMARY.length)]);
+                }
+
+                // 仅当操作数 >= 3 时，才有可能生成括号
+                if (operands >= 3 && rand.nextBoolean() && i < operands - 1) {
+                    int num1 = rand.nextInt(50) + 1;
+                    String innerOp = OPS_PRIMARY[rand.nextInt(OPS_PRIMARY.length)];
+                    int num2;
+                    if (innerOp.equals("/")) {
+                        num2 = getDivisor(num1);
+                    } else {
+                        num2 = rand.nextInt(50) + 1;
+                    }
+                    parts.add("(" + num1 + " " + innerOp + " " + num2 + ")");
+                    i++; // 括号表达式计为2个操作数
+                } else {
+                    int num;
+                    if (i > 0 && parts.get(parts.size() - 1).equals("/")) {
+                        String dividendStr = parts.get(parts.size() - 2);
+                        if (dividendStr.startsWith("(")) {
+                            // 为避免 (a+b)/c 这种复杂情况无法保证整数结果，直接替换运算符
+                            parts.set(parts.size() - 1, OPS_PRIMARY[rand.nextInt(3)]); // +, -, *
+                            num = rand.nextInt(100) + 1;
+                        } else {
+                            int dividend = Integer.parseInt(dividendStr);
+                            num = getDivisor(dividend);
+                        }
+                    } else {
+                        num = rand.nextInt(100) + 1;
+                    }
+                    parts.add(String.valueOf(num));
+                }
+            }
+            String expression = String.join(" ", parts);
+            problem = createProblem(expression);
+            result = problem.getResult();
+            // 循环直到答案为非负整数
+        } while (result < 0 || Double.isNaN(result) || Math.abs(result - Math.round(result)) > 0.0001);
+
+        return problem;
+    }
+
+
+    public static Problem generateMiddleExpr() {
+        int operands = rand.nextInt(5) + 1;
+        StringBuilder expr = new StringBuilder();
+        boolean hasSquareOrSqrt = false;
+
+        for (int i = 0; i < operands; i++) {
+            if (i > 0) {
+                expr.append(" ").append(OPS_MIDDLE[rand.nextInt(OPS_MIDDLE.length)]).append(" ");
+            }
+            int num = rand.nextInt(100) + 1;
+            if (!hasSquareOrSqrt && rand.nextBoolean()) {
+                expr.append(rand.nextBoolean() ? "sqrt(" + num + ")" : num + "^2");
+                hasSquareOrSqrt = true;
+            } else {
+                expr.append(num);
+            }
+        }
+
+        if (!hasSquareOrSqrt) {
+            expr.append(" + ").append(rand.nextInt(50) + 1).append("^2");
+        }
+
+        return createProblem(expr.toString());
+    }
+
+    public static Problem generateHighExpr() {
+        int attempts = 0;
+        final int maxAttempts = 10;
+        
+        while (attempts < maxAttempts) {
+            int operands = rand.nextInt(3) + 2; // 2-4个操作数
+            StringBuilder expr = new StringBuilder();
+            boolean hasTrig = false;
+
+            for (int i = 0; i < operands; i++) {
+                if (i > 0) {
+                    String[] validOps = {"+", "-", "*", "/"};
+                    String op = validOps[rand.nextInt(validOps.length)];
+                    expr.append(" ").append(op).append(" ");
+                }
+                
+                // 强制至少有一个操作数是三角函数
+                if (!hasTrig && (i == operands - 1 || rand.nextBoolean())) {
+                    String[] funcs = {"sin", "cos", "tan"};
+                    String func = funcs[rand.nextInt(funcs.length)];
+                    int angle = rand.nextInt(90) + 1; // 1-90度
+                    expr.append(func).append("(").append(angle).append(")");
+                    hasTrig = true;
+                } else {
+                    // 其他操作数可以是普通数字、平方或开方
+                    int num = rand.nextInt(100) + 1;
+                    if (rand.nextBoolean() && hasTrig) { // 确保已经有三角函数后再添加其他函数
+                        if (rand.nextBoolean()) {
+                            expr.append(num).append("^2");
+                        } else {
+                            expr.append("sqrt(").append(num).append(")");
+                        }
+                    } else {
+                        expr.append(num);
+                    }
+                }
+            }
+
+            // 如果没有三角函数，强制添加一个
+            if (!hasTrig) {
+                String[] funcs = {"sin", "cos", "tan"};
+                String func = funcs[rand.nextInt(funcs.length)];
+                int angle = rand.nextInt(90) + 1;
+                
+                if (rand.nextBoolean()) {
+                    // 在开头添加
+                    expr.insert(0, func + "(" + angle + ") + ");
+                } else {
+                    // 在结尾添加
+                    expr.append(" + ").append(func).append("(").append(angle).append(")");
+                }
+                hasTrig = true;
+            }
+
+            String expression = expr.toString();
+            
+            // 验证表达式
+            Problem problem = createProblem(expression);
+            if (problem != null) {
+                return problem;
+            }
+            
+            attempts++;
+            System.err.println("生成高中题目失败，尝试次数: " + attempts + ", 表达式: " + expression);
+        }
+        
+        return createProblem("sin(30) + cos(60)");
+    }
+    
+}

src/util/FileUtils.java

@@ -0,0 +1,79 @@
+package util;
+
+import generator.Problem;
+import java.io.*;
+import java.text.SimpleDateFormat;
+import java.util.*;
+
+public class FileUtils {
+    private static final String FOLDER_PATH = "exams/";
+
+    public static String getUserFolder(String username) {
+        String folder = FOLDER_PATH + username;
+        File dir = new File(folder);
+        if (!dir.exists()) {
+            dir.mkdirs();
+        }
+        return folder;
+    }
+
+    private static void processHistoryFile(File file, Set<String> history) {
+        try (BufferedReader br = new BufferedReader(new FileReader(file))) {
+            String line;
+            while ((line = br.readLine()) != null) {
+                if (!line.trim().isEmpty() && line.matches("^\\d+\\..*")) {
+                    // 仅提取题干 (表达式字符串) 用于查重
+                    history.add(line.substring(line.indexOf('.') + 1).trim());
+                }
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static Set<String> loadHistory(String username) {
+        Set<String> history = new HashSet<>();
+        File dir = new File(getUserFolder(username));
+        File[] files = dir.listFiles((d, name) -> name.endsWith(".txt"));
+
+        if (files != null) {
+            for (File file : files) {
+                processHistoryFile(file, history);
+            }
+        }
+        return history;
+    }
+
+    private static void writeProblem(BufferedWriter bw, int index, Problem problem) throws IOException {
+        bw.write(index + "." + problem.getExpression());
+        bw.newLine();
+
+        char optionChar = 'A';
+        StringBuilder optionsLine = new StringBuilder();
+        for (String option : problem.getOptions()) {
+            optionsLine.append(optionChar++).append(". ").append(option).append("  ");
+        }
+
+        bw.write(optionsLine.toString().trim());
+        bw.newLine();
+        bw.write("答案: " + problem.getCorrectAnswerOption());
+        bw.newLine();
+        bw.newLine();
+    }
+
+    public static void saveProblems(String username, List<Problem> problems) {
+        String folder = getUserFolder(username);
+        String timestamp = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss").format(new Date());
+        String filename = folder + "/" + timestamp + ".txt";
+
+        try (BufferedWriter bw = new BufferedWriter(new FileWriter(filename))) {
+            int index = 1;
+            for (Problem problem : problems) {
+                writeProblem(bw, index++, problem);
+            }
+            System.out.println("卷子已保存到: " + filename);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}

src/util/ModifyUtils.java

@@ -0,0 +1,76 @@
+package util;
+
+import java.io.*;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Utility class to modify specific fields in user.txt.
+ * 替换了 ModifyClass.java 和 ModifyPassword.java。
+ */
+public class ModifyUtils {
+
+    private static List<String> readAllLines(String filePath, List<String> lines) throws IOException {
+        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                lines.add(line);
+            }
+        }
+        return lines;
+    }
+
+    private static void writeAllLines(String filePath, List<String> lines) throws IOException {
+        try (BufferedWriter writer = new BufferedWriter(new FileWriter(filePath))) {
+            for (String l : lines) {
+                writer.write(l + System.lineSeparator());
+            }
+        }
+    }
+
+    private static int findTargetLine(List<String> lines, String targetName) {
+        for (int i = 0; i < lines.size(); i++) {
+            String line = lines.get(i).trim();
+            if (line.isEmpty()) continue;
+
+            String[] parts = line.split("\\s+");
+            if (parts.length > 0 && parts[0].equals(targetName)) {
+                return i; // 0-based index
+            }
+        }
+        return -1;
+    }
+
+    // 核心逻辑：修改文件中特定用户的某个字段 (0-based)
+    public static int modifyFileField(String filePath, String targetName,
+                                      int fieldIndex, String newValue) {
+        List<String> lines = new ArrayList<>();
+        try {
+            readAllLines(filePath, lines);
+        } catch (IOException e) {
+            System.err.println("读取文件错误: " + e.getMessage());
+            return -1;
+        }
+
+        int idx = findTargetLine(lines, targetName);
+        if (idx == -1) {
+            return -1;
+        }
+
+        String[] parts = lines.get(idx).trim().split("\\s+");
+        if (parts.length > fieldIndex) {
+            parts[fieldIndex] = newValue;
+            lines.set(idx, String.join(" ", parts));
+            try {
+                writeAllLines(filePath, lines);
+                return idx + 1; // 返回 1-based 行号
+            } catch (IOException e) {
+                System.err.println("写入文件错误: " + e.getMessage());
+                return -1;
+            }
+        } else {
+            System.out.println("目标行元素不足。");
+            return -1;
+        }
+    }
+}