修改登录逻辑

src/Application.java

@@ -79,10 +79,10 @@ public class Application {
    * 处理用户已登录状态下的逻辑。
    */
   private void handleLoggedInState() throws IOException {
-    String currentLevelName = sessionManager.getCurrentLevelName();
+    String currentLevel = sessionManager.getCurrentLevelName();
     System.out.printf(
             "当前选择为%s出题。请输入生成题目数量（10-30），或输入 '切换为XX'，或输入 '-1' 退出登录：%n",
-            currentLevelName);
+            currentLevel);
     String input = scanner.nextLine().trim();
 
       if ("-1".equals(input)) {
@@ -90,10 +90,7 @@ public class Application {
       } else if (isSwitchCommand(input)) {
         handleSwitchLevel(input);
       } else if (isNumeric(input)) {
-        int count = Integer.parseInt(input);
-        if(validateGenerateCount(count)) {
-          handleGenerateProblems(count);
-        }
+        handleGenerateProblems(input);
       } else {
         System.out.println("无效的选项，请重新输入");
       }
@@ -116,7 +113,8 @@ public class Application {
     }
   }
 
-  private void handleGenerateProblems(int count) throws IOException {
+  private void handleGenerateProblems(String input) throws IOException {
+    int count = Integer.parseInt(input);
     User currentUser = sessionManager.getCurrentUser();
     System.out.println("正在加载历史题目，请稍候...");
     Set<String> history = fileService.loadAllProblemHistory(currentUser);
@@ -125,11 +123,10 @@ public class Application {
     System.out.println("正在生成 " + count + " 道不重复的新题目...");
     IProblemGenerator generator = sessionManager.getCurrentGenerator();
     List<Equation> newProblems = generator.generate(count, history);
-    //命令行显示生成题目
+    // 命令行显示生成题目
     for (int i = 0; i < newProblems.size(); i++) {
       String problemLine = (i + 1) + ". " + newProblems.get(i).toString();
       System.out.println(problemLine);
-      // 满足题目之间空一行的格式要求
       System.out.println();
     }
 
@@ -143,15 +140,15 @@ public class Application {
   }
 
   private boolean isNumeric(String str) {
-    return str != null && str.matches("-?\\d+");
-  }
-
-  private boolean validateGenerateCount(int count) {
-    if (count < 10 || count > 30) {
-      System.out.println("生成数量必须在10到30之间。");
-      return false;
+    if (str != null && str.matches("\\d+")){
+      int count = Integer.parseInt(str);
+      if (count < 10 || count > 30) {
+        System.out.println("生成数量必须在10到30之间。");
+        return false;
+      }
+      return true;
     }
-    return true;
+    return false;
   }
 
   public static void main(String[] args) throws IOException {

src/AuthService.java

@@ -17,7 +17,7 @@ public class AuthService {
    *
    * @param username 用户名
    * @param password 密码
-   * @return 如果认证成功，返回对应的 User 对象；否则返回一个空的 Optional
+   * @return 如果认证成功，返回ture,否则返回false
    */
   public Optional<User> login(String username, String password) {
     Optional<User> userOptional = userRepository.findByUsername(username);

src/SessionManager.java

@@ -9,6 +9,7 @@ public final class SessionManager {
 
   private User currentUser;
   private IProblemGenerator currentGenerator;
+  private String currentLevel;
 
   private SessionManager() {
     // 私有构造函数，防止外部实例化
@@ -74,6 +75,8 @@ public final class SessionManager {
   }
 
   private void setGeneratorByLevel(String level) {
+    String tempLevel = this.currentLevel;
+    this.currentLevel = level;
     switch (level) {
       case "小学":
         this.currentGenerator = new ElementaryProblemGenerator();
@@ -86,6 +89,7 @@ public final class SessionManager {
         break;
       default:
         System.out.println("错误的难度等级: " + level);
+        this.currentLevel = tempLevel;
     }
   }
 
@@ -95,13 +99,6 @@ public final class SessionManager {
    * @return 中文级别名称，如 "小学"
    */
   public String getCurrentLevelName() {
-    if (currentGenerator instanceof HighSchoolProblemGenerator) {
-      return "高中";
-    } else if (currentGenerator instanceof MiddleSchoolProblemGenerator) {
-      return "初中";
-    }else if (currentGenerator instanceof ElementaryProblemGenerator) {
-      return "小学";
-    }
-    return "未知";
+    return currentLevel;
   }
 }