初步完成实体和工具配置

src/main/java/com/quizgenerator/common/Level.java

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+package com.quizgenerator.common;
+
+import lombok.Getter;
+
+/** 三种习题等级. */
+@Getter
+public enum Level {
+  PRIMARY("小学"),
+  JUNIOR_HIGH("初中"),
+  SENIOR_HIGH("高中");
+
+  private final String displayName;
+
+  Level(String displayName) {
+    this.displayName = displayName;
+  }
+
+  /**
+   * 获取等级.
+   *
+   * @param text s
+   * @return Level
+   */
+  public static Level fromString(String text) {
+    for (Level b : Level.values()) {
+      if (b.displayName.equalsIgnoreCase(text)) {
+        return b;
+      }
+    }
+    return null;
+  }
+}

src/main/java/com/quizgenerator/common/QuestionUtils.java

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+package com.quizgenerator.common;
+
+import java.util.Random;
+
+/** 一个用于题目生成的辅助工具类. 包含所有生成器可能共享的静态方法。 */
+public final class QuestionUtils {
+
+  private static final Random RANDOM = new Random();
+
+  private QuestionUtils() {}
+
+  /**
+   * 检查一个字符串是否可以被解析为整数.
+   *
+   * @param str 要检查的字符串
+   * @return 如果是数字则为 true, 否则为 false
+   */
+  public static boolean isNotNumeric(String str) {
+    if (str == null) {
+      return true; // null 不是数字，所以返回 true
+    }
+
+    try {
+      Integer.parseInt(str);
+      return false; // 能成功转换，说明是数字，所以返回 false
+    } catch (NumberFormatException e) {
+      return true; // 转换失败，说明不是数字，所以返回 true
+    }
+  }
+
+  /**
+   * 返回一个随机的四则运算符 (+, -, *, /).
+   *
+   * @return 随机的运算符字符
+   */
+  public static char getRandomOperator() {
+    char[] operators = {'+', '-', '*', '/'};
+    return operators[RANDOM.nextInt(operators.length)];
+  }
+
+  /**
+   * 返回一个1到100之间的随机操作数.
+   *
+   * @return 随机整数
+   */
+  public static int getRandomOperand() {
+    return RANDOM.nextInt(100) + 1;
+  }
+}

src/main/java/com/quizgenerator/dao/UserDataBase.java

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+package com.quizgenerator.dao;
+
+import com.quizgenerator.common.Level;
+import com.quizgenerator.entity.User;
+import java.util.HashMap;
+import java.util.Map;
+
+/** 由于数据较少，且不好提交数据库，所以选择写死在代码里面. */
+public class UserDataBase {
+  private static final Map<String, User> userDatabase = new HashMap<>();
+
+  // TODO 存储为加密后的密码
+  static {
+    // 小学
+    userDatabase.put("张三1", new User("张三1", "123", Level.PRIMARY));
+    userDatabase.put("张三2", new User("张三2", "123", Level.PRIMARY));
+    userDatabase.put("张三3", new User("张三3", "123", Level.PRIMARY));
+    // 初中
+    userDatabase.put("李四1", new User("李四1", "123", Level.JUNIOR_HIGH));
+    userDatabase.put("李四2", new User("李四2", "123", Level.JUNIOR_HIGH));
+    userDatabase.put("李四3", new User("李四3", "123", Level.JUNIOR_HIGH));
+    // 高中
+    userDatabase.put("王五1", new User("王五1", "123", Level.SENIOR_HIGH));
+    userDatabase.put("王五2", new User("王五2", "123", Level.SENIOR_HIGH));
+    userDatabase.put("王五3", new User("王五3", "123", Level.SENIOR_HIGH));
+  }
+
+  /**
+   * 根据用户名查找用户.
+   *
+   * @param username 用户名
+   * @return 如果找到则返回User对象，否则返回null
+   */
+  public static User findByUsername(String username) {
+    return userDatabase.get(username);
+  }
+}

src/main/java/com/quizgenerator/entity/User.java

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+package com.quizgenerator.entity;
+
+import com.quizgenerator.common.Level;
+import lombok.Data;
+
+/** User类. */
+@Data
+public class User {
+  private final String username;
+  private final String password;
+  private final Level level;
+
+  /*public User(String username, String password, Level level) {
+      this.username = username;
+      this.password = password;
+      this.level = level;
+  }
+
+  public String getUsername() {
+      return username;
+  }
+
+  public String getPassword() {
+      return password;
+  }
+
+  public Level getLevel() {
+      return level;
+  }*/
+}