完成作业

BindPort.java

@@ -0,0 +1,24 @@
+import java.net.ServerSocket;
+import java.net.Socket;
+
+public class BindPort {
+    public static void main(String[] args) {
+        try {
+            // 尝试绑定到端口8081
+            ServerSocket serverSocket = new ServerSocket(8081);
+            System.out.println("Successfully bound to port 8081");
+            
+            // 等待客户端连接
+            System.out.println("Waiting for client connections...");
+            Socket clientSocket = serverSocket.accept();
+            System.out.println("Client connected: " + clientSocket.getRemoteSocketAddress());
+            
+            // 关闭连接
+            clientSocket.close();
+            serverSocket.close();
+        } catch (Exception e) {
+            System.err.println("Error binding to port 8081: " + e.getMessage());
+            e.printStackTrace();
+        }
+    }
+}

TestApi.java

@@ -0,0 +1,39 @@
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class TestApi {
+    public static void main(String[] args) {
+        try {
+            URL url = new URL("http://127.0.0.1:8081/api/playlists");
+            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+            conn.setRequestMethod("GET");
+            conn.setRequestProperty("Content-Type", "application/json");
+            
+            System.out.println("Sending GET request to: " + url.toString());
+            System.out.println("Connection timeout: " + conn.getConnectTimeout());
+            System.out.println("Read timeout: " + conn.getReadTimeout());
+            
+            int responseCode = conn.getResponseCode();
+            System.out.println("Response Code: " + responseCode);
+            
+            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
+            String inputLine;
+            StringBuffer response = new StringBuffer();
+            
+            while ((inputLine = in.readLine()) != null) {
+                response.append(inputLine);
+            }
+            in.close();
+            
+            System.out.println("Response Body: " + response.toString());
+            conn.disconnect();
+            
+        } catch (Exception e) {
+            System.out.println("Exception occurred: " + e.getClass().getName());
+            System.out.println("Exception message: " + e.getMessage());
+            e.printStackTrace();
+        }
+    }
+}

TestPort.java

@@ -0,0 +1,13 @@
+import java.net.Socket;
+
+public class TestPort {
+    public static void main(String[] args) {
+        try {
+            Socket socket = new Socket("127.0.0.1", 8081);
+            System.out.println("Successfully connected to port 8081");
+            socket.close();
+        } catch (Exception e) {
+            System.out.println("Failed to connect to port 8081: " + e.getMessage());
+        }
+    }
+}

src/main/java/com/vibevault/config/SecurityConfig.java

@@ -39,13 +39,31 @@ public class SecurityConfig {
 
     @Bean
     public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
-        // TODO: 配置安全规则
-        // 提示：
-        // - 使用 http.authorizeHttpRequests() 配置路径权限
-        // - 使用 http.csrf(csrf -> csrf.disable()) 禁用 CSRF
-        // - 使用 http.sessionManagement() 配置无状态会话
-        // - 使用 http.exceptionHandling() 配置 401 响应
-        // - 使用 http.addFilterBefore() 添加 JWT 过滤器
+        http
+            // 配置路径权限
+            .authorizeHttpRequests(auth -> auth
+                // 公开接口无需认证
+                .requestMatchers("/api/auth/**").permitAll()
+                .requestMatchers(HttpMethod.GET, "/api/playlists").permitAll()
+                .requestMatchers(HttpMethod.GET, "/api/playlists/{id}").permitAll()
+                .requestMatchers(HttpMethod.GET, "/api/playlists/search").permitAll()
+                // 其他所有请求需要认证
+                .anyRequest().authenticated()
+            )
+            // 禁用 CSRF
+            .csrf(csrf -> csrf.disable())
+            // 配置无状态会话
+            .sessionManagement(session -> session
+                .sessionCreationPolicy(SessionCreationPolicy.STATELESS)
+            )
+            // 配置未认证访问受保护资源返回 401
+            .exceptionHandling(ex -> ex
+                .authenticationEntryPoint((request, response, authException) -> {
+                    response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized");
+                })
+            )
+            // 添加 JWT 过滤器
+            .addFilterBefore(jwtAuthenticationFilter, UsernamePasswordAuthenticationFilter.class);
         
         return http.build();
     }

src/main/java/com/vibevault/controller/AuthController.java

@@ -36,9 +36,45 @@ public class AuthController {
         this.jwtService = jwtService;
     }
 
-    // TODO: 实现 POST /api/auth/register (状态码 201)
+    // 实现 POST /api/auth/register (状态码 201)
+    @PostMapping("/register")
+    @ResponseStatus(HttpStatus.CREATED)
+    public RegisterResponse register(@RequestBody RegisterRequest request) {
+        // 检查用户名是否已存在
+        if (userRepository.existsByUsername(request.username())) {
+            throw new ResponseStatusException(HttpStatus.CONFLICT, "Username already exists");
+        }
         
-    // TODO: 实现 POST /api/auth/login
+        // 创建新用户
+        User user = new User(request.username(), passwordEncoder.encode(request.password()));
+        // 设置默认角色
+        user.setRole("ROLE_USER");
+        
+        // 保存用户到数据库
+        userRepository.save(user);
+        
+        // 返回注册响应
+        return new RegisterResponse("User registered successfully", request.username());
+    }
+
+    // 实现 POST /api/auth/login
+    @PostMapping("/login")
+    public LoginResponse login(@RequestBody LoginRequest request) {
+        // 查找用户
+        User user = userRepository.findByUsername(request.username())
+                .orElseThrow(() -> new ResponseStatusException(HttpStatus.UNAUTHORIZED, "Invalid credentials"));
+        
+        // 验证密码
+        if (!passwordEncoder.matches(request.password(), user.getPassword())) {
+            throw new ResponseStatusException(HttpStatus.UNAUTHORIZED, "Invalid credentials");
+        }
+        
+        // 生成 JWT token
+        String token = jwtService.generateToken(user.getUsername());
+        
+        // 返回登录响应
+        return new LoginResponse(token, user.getUsername());
+    }
 }
 
 /**

src/main/java/com/vibevault/controller/HealthCheckController.java

@@ -0,0 +1,14 @@
+package com.vibevault.controller;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api/health")
+public class HealthCheckController {
+    @GetMapping
+    public String healthCheck() {
+        return "OK";
+    }
+}

src/main/java/com/vibevault/controller/PlaylistController.java

@@ -39,19 +39,61 @@ public class PlaylistController {
         this.playlistService = playlistService;
     }
 
-    // TODO: 实现 GET /api/playlists
+    // 实现 GET /api/playlists - 获取所有歌单（公开）
+    @GetMapping
+    public List<PlaylistDTO> getAllPlaylists() {
+        return playlistService.getAllPlaylists();
+    }
 
-    // TODO: 实现 GET /api/playlists/{id}
+    // 实现 GET /api/playlists/{id} - 获取指定歌单（公开）
+    @GetMapping("/{id}")
+    public PlaylistDTO getPlaylistById(@PathVariable Long id) {
+        return playlistService.getPlaylistById(id);
+    }
 
-    // TODO: 实现 POST /api/playlists (状态码 201)
+    // 实现 POST /api/playlists - 创建歌单（需认证）
+    @PostMapping
+    @ResponseStatus(HttpStatus.CREATED)
+    public PlaylistDTO createPlaylist(@RequestBody PlaylistCreateDTO playlistCreateDTO, Authentication authentication) {
+        String username = authentication.getName();
+        return playlistService.createPlaylist(playlistCreateDTO.name(), username);
+    }
 
-    // TODO: 实现 POST /api/playlists/{id}/songs (状态码 201)
+    // 实现 POST /api/playlists/{id}/songs - 添加歌曲（需认证）
+    @PostMapping("/{id}/songs")
+    @ResponseStatus(HttpStatus.CREATED)
+    public PlaylistDTO addSongToPlaylist(@PathVariable Long id, @RequestBody SongCreateDTO songCreateDTO, Authentication authentication) {
+        String username = authentication.getName();
+        return playlistService.addSongToPlaylist(id, songCreateDTO, username);
+    }
 
-    // TODO: 实现 DELETE /api/playlists/{playlistId}/songs/{songId} (状态码 204)
+    // 实现 DELETE /api/playlists/{playlistId}/songs/{songId} - 移除歌曲（需认证）
+    @DeleteMapping("/{playlistId}/songs/{songId}")
+    @ResponseStatus(HttpStatus.NO_CONTENT)
+    public void removeSongFromPlaylist(@PathVariable Long playlistId, @PathVariable Long songId, Authentication authentication) {
+        String username = authentication.getName();
+        playlistService.removeSongFromPlaylist(playlistId, songId, username);
+    }
 
-    // TODO: 实现 DELETE /api/playlists/{id} (状态码 204)
+    // 实现 DELETE /api/playlists/{id} - 删除歌单（需认证）
+    @DeleteMapping("/{id}")
+    @ResponseStatus(HttpStatus.NO_CONTENT)
+    public void deletePlaylist(@PathVariable Long id, Authentication authentication) {
+        String username = authentication.getName();
+        playlistService.deletePlaylist(id, username);
+    }
 
-    // TODO [Advanced]: 实现 GET /api/playlists/search?keyword=xxx
+    // [Advanced] 实现 GET /api/playlists/search?keyword=xxx - 搜索歌单
+    @GetMapping("/search")
+    public List<PlaylistDTO> searchPlaylists(@RequestParam String keyword) {
+        return playlistService.searchPlaylists(keyword);
+    }
 
-    // TODO [Advanced]: 实现 POST /api/playlists/{id}/copy?newName=xxx (状态码 201)
+    // [Advanced] 实现 POST /api/playlists/{id}/copy?newName=xxx - 复制歌单
+    @PostMapping("/{id}/copy")
+    @ResponseStatus(HttpStatus.CREATED)
+    public PlaylistDTO copyPlaylist(@PathVariable Long id, @RequestParam String newName, Authentication authentication) {
+        String username = authentication.getName();
+        return playlistService.copyPlaylist(id, newName, username);
+    }
 }

src/main/java/com/vibevault/model/Playlist.java

@@ -16,14 +16,22 @@ import java.util.List;
  * - 一个歌单包含多首歌曲（一对多关系）
  * - 删除歌单时应级联删除其中的歌曲
  */
+@Entity
+@Table(name = "playlists")
 public class Playlist {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    @Column(name = "name", nullable = false)
     private String name;
 
+    @ManyToOne
+    @JoinColumn(name = "owner_id", nullable = false)
     private User owner;
 
+    @OneToMany(mappedBy = "playlist", cascade = CascadeType.ALL, orphanRemoval = true)
     private List<Song> songs = new ArrayList<>();
 
     protected Playlist() {
@@ -59,7 +67,8 @@ public class Playlist {
      * 提示：需要维护双向关系
      */
     public void addSong(Song song) {
-        // TODO: 实现添加歌曲逻辑
+        songs.add(song);
+        song.setPlaylist(this);
     }
 
     /**
@@ -67,6 +76,7 @@ public class Playlist {
      * 提示：需要维护双向关系
      */
     public void removeSong(Song song) {
-        // TODO: 实现移除歌曲逻辑
+        songs.remove(song);
+        song.setPlaylist(null);
     }
 }

src/main/java/com/vibevault/model/Song.java

@@ -10,16 +10,25 @@ import jakarta.persistence.*;
  * - id 作为自增主键
  * - 每首歌曲属于一个歌单（多对一关系）
  */
+@Entity
+@Table(name = "songs")
 public class Song {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    @Column(name = "title", nullable = false)
     private String title;
 
+    @Column(name = "artist", nullable = false)
     private String artist;
 
+    @Column(name = "duration_in_seconds", nullable = false)
     private int durationInSeconds;
 
+    @ManyToOne
+    @JoinColumn(name = "playlist_id", nullable = false)
     private Playlist playlist;
 
     public Song() {

src/main/java/com/vibevault/model/User.java

@@ -12,15 +12,22 @@ import jakarta.persistence.*;
  * - password 不能为空
  * - [Challenge] 支持用户角色（如 ROLE_USER, ROLE_ADMIN）
  */
+@Entity
+@Table(name = "users")
 public class User {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    @Column(name = "username", unique = true, nullable = false)
     private String username;
 
+    @Column(name = "password", nullable = false)
     private String password;
 
     // [Challenge] 用户角色，默认为 ROLE_USER
+    @Column(name = "role", nullable = false)
     private String role = "ROLE_USER";
 
     protected User() {
@@ -53,6 +60,14 @@ public class User {
         return role;
     }
 
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
     public void setRole(String role) {
         this.role = role;
     }

src/main/java/com/vibevault/repository/PlaylistRepository.java

@@ -18,5 +18,6 @@ import java.util.List;
  */
 @Repository
 public interface PlaylistRepository extends JpaRepository<Playlist, Long> {
-    // TODO [Advanced]: 添加高级查询方法
+    List<Playlist> findByOwner(User owner);
+    List<Playlist> findByNameContainingIgnoreCase(String keyword);
 }

src/main/java/com/vibevault/repository/SongRepository.java

@@ -0,0 +1,14 @@
+package com.vibevault.repository;
+
+import com.vibevault.model.Song;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+/**
+ * 歌曲仓库接口
+ * 
+ * 基础功能由 JpaRepository 提供
+ */
+@Repository
+public interface SongRepository extends JpaRepository<Song, Long> {
+}

src/main/java/com/vibevault/repository/UserRepository.java

@@ -15,5 +15,6 @@ import java.util.Optional;
  */
 @Repository
 public interface UserRepository extends JpaRepository<User, Long> {
-    // TODO: 添加必要的查询方法
+    Optional<User> findByUsername(String username);
+    boolean existsByUsername(String username);
 }

src/main/java/com/vibevault/security/JwtAuthenticationFilter.java

@@ -45,17 +45,50 @@ public class JwtAuthenticationFilter extends OncePerRequestFilter {
             @NonNull FilterChain filterChain
     ) throws ServletException, IOException {
         
-        // TODO: 实现 JWT 认证逻辑
-        // 1. 从请求头获取 Authorization
-        // 2. 检查是否以 "Bearer " 开头
-        // 3. 提取 token 并验证
-        // 4. 如果有效，创建 Authentication 并设置到 SecurityContextHolder
-        // 
-        // 提示：
-        // - 使用 request.getHeader("Authorization") 获取头
-        // - 使用 jwtService.extractUsername() 和 jwtService.isTokenValid()
-        // - 使用 UsernamePasswordAuthenticationToken 创建认证对象
-        // - 使用 SecurityContextHolder.getContext().setAuthentication() 设置
+        // 从请求头获取 Authorization
+        final String authHeader = request.getHeader("Authorization");
+        final String jwt;
+        final String username;
+        
+        // 检查是否以 "Bearer " 开头
+        if (authHeader == null || !authHeader.startsWith("Bearer ")) {
+            filterChain.doFilter(request, response);
+            return;
+        }
+        
+        // 提取 token
+        jwt = authHeader.substring(7);
+        // 从 token 中提取用户名
+        username = jwtService.extractUsername(jwt);
+        
+        // 如果用户名不为空且当前没有认证信息
+        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
+            // 从数据库中查找用户
+            User user = userRepository.findByUsername(username)
+                    .orElse(null);
+            
+            if (user != null && jwtService.isTokenValid(jwt, username)) {
+                // 设置用户角色
+                List<SimpleGrantedAuthority> authorities = Collections.singletonList(
+                        new SimpleGrantedAuthority(user.getRole())
+                );
+                
+                // 创建认证对象
+                UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken(
+                        user.getUsername(),
+                        null,
+                        authorities
+                );
+                
+                // 设置认证详情
+                authToken.setDetails(
+                        new WebAuthenticationDetailsSource().buildDetails(request)
+                );
+                
+                // 设置到 SecurityContextHolder
+                SecurityContextHolder.getContext().setAuthentication(authToken);
+            }
+        }
         
         filterChain.doFilter(request, response);
     }

src/main/java/com/vibevault/security/JwtService.java

@@ -1,5 +1,6 @@
 package com.vibevault.security;
 
+import io.jsonwebtoken.Claims;
 import io.jsonwebtoken.Jwts;
 import io.jsonwebtoken.security.Keys;
 import org.springframework.beans.factory.annotation.Value;
@@ -8,6 +9,7 @@ import org.springframework.stereotype.Service;
 import javax.crypto.SecretKey;
 import java.nio.charset.StandardCharsets;
 import java.util.Date;
+import java.util.function.Function;
 
 /**
  * JWT 服务
@@ -30,26 +32,60 @@ public class JwtService {
      * 为用户生成 JWT token
      */
     public String generateToken(String username) {
-        // TODO: 实现 token 生成
-        // 提示：使用 Jwts.builder()
-        throw new UnsupportedOperationException("待实现");
+        return Jwts.builder()
+                .setSubject(username)
+                .setIssuedAt(new Date(System.currentTimeMillis()))
+                .setExpiration(new Date(System.currentTimeMillis() + expiration))
+                .signWith(getSigningKey())
+                .compact();
     }
 
     /**
      * 从 token 中提取用户名
      */
     public String extractUsername(String token) {
-        // TODO: 实现用户名提取
-        // 提示：使用 Jwts.parser()
-        throw new UnsupportedOperationException("待实现");
+        return extractClaim(token, Claims::getSubject);
     }
 
     /**
      * 验证 token 是否有效
      */
     public boolean isTokenValid(String token, String username) {
-        // TODO: 实现 token 验证
-        throw new UnsupportedOperationException("待实现");
+        final String extractedUsername = extractUsername(token);
+        return (extractedUsername.equals(username)) && !isTokenExpired(token);
+    }
+
+    /**
+     * 从 JWT 令牌中提取特定声明
+     */
+    private <T> T extractClaim(String token, Function<Claims, T> claimsResolver) {
+        final Claims claims = extractAllClaims(token);
+        return claimsResolver.apply(claims);
+    }
+
+    /**
+     * 从 JWT 令牌中提取所有声明
+     */
+    private Claims extractAllClaims(String token) {
+        return Jwts.parser()
+                .verifyWith(getSigningKey())
+                .build()
+                .parseSignedClaims(token)
+                .getPayload();
+    }
+
+    /**
+     * 检查令牌是否过期
+     */
+    private boolean isTokenExpired(String token) {
+        return extractExpiration(token).before(new Date());
+    }
+
+    /**
+     * 从令牌中提取过期时间
+     */
+    private Date extractExpiration(String token) {
+        return extractClaim(token, Claims::getExpiration);
     }
 
     /**

src/main/java/com/vibevault/service/PlaylistServiceImpl.java

@@ -14,6 +14,7 @@ import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * 歌单服务实现
@@ -37,60 +38,119 @@ public class PlaylistServiceImpl implements PlaylistService {
 
     @Override
     public List<PlaylistDTO> getAllPlaylists() {
-        // TODO: 实现获取所有歌单
-        throw new UnsupportedOperationException("待实现");
+        List<Playlist> playlists = playlistRepository.findAll();
+        return playlists.stream()
+                .map(this::toDTO)
+                .collect(Collectors.toList());
     }
 
     @Override
     public PlaylistDTO getPlaylistById(Long id) {
-        // TODO: 实现根据 ID 获取歌单，不存在时抛出 ResourceNotFoundException
-        throw new UnsupportedOperationException("待实现");
+        Playlist playlist = playlistRepository.findById(id)
+                .orElseThrow(() -> new ResourceNotFoundException("Playlist not found with id: " + id));
+        return toDTO(playlist);
     }
 
     @Override
     @Transactional
     public PlaylistDTO createPlaylist(String name, String ownerUsername) {
-        // TODO: 实现创建歌单
-        throw new UnsupportedOperationException("待实现");
+        User owner = userRepository.findByUsername(ownerUsername)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found with username: " + ownerUsername));
+        
+        Playlist playlist = new Playlist(name, owner);
+        Playlist savedPlaylist = playlistRepository.save(playlist);
+        
+        return toDTO(savedPlaylist);
     }
 
     @Override
     @Transactional
-    public PlaylistDTO addSongToPlaylist(Long playlistId, SongCreateDTO song, String username) {
-        // TODO: 实现添加歌曲到歌单
-        // [Challenge] 需要检查用户是否有权限操作此歌单
-        throw new UnsupportedOperationException("待实现");
+    public PlaylistDTO addSongToPlaylist(Long playlistId, SongCreateDTO songDTO, String username) {
+        Playlist playlist = playlistRepository.findById(playlistId)
+                .orElseThrow(() -> new ResourceNotFoundException("Playlist not found with id: " + playlistId));
+        
+        // 检查用户是否有权限操作此歌单
+        checkPermission(playlist, username);
+        
+        // 创建新歌曲
+        Song song = new Song(songDTO.title(), songDTO.artist(), songDTO.durationInSeconds());
+        
+        // 添加歌曲到歌单
+        playlist.addSong(song);
+        
+        // 保存更新后的歌单
+        Playlist updatedPlaylist = playlistRepository.save(playlist);
+        
+        return toDTO(updatedPlaylist);
     }
 
     @Override
     @Transactional
     public void removeSongFromPlaylist(Long playlistId, Long songId, String username) {
-        // TODO: 实现从歌单移除歌曲
-        // [Challenge] 需要检查用户是否有权限操作此歌单
-        throw new UnsupportedOperationException("待实现");
+        Playlist playlist = playlistRepository.findById(playlistId)
+                .orElseThrow(() -> new ResourceNotFoundException("Playlist not found with id: " + playlistId));
+        
+        // 检查用户是否有权限操作此歌单
+        checkPermission(playlist, username);
+        
+        // 查找歌曲
+        Song song = playlist.getSongs().stream()
+                .filter(s -> s.getId().equals(songId))
+                .findFirst()
+                .orElseThrow(() -> new ResourceNotFoundException("Song not found with id: " + songId));
+        
+        // 从歌单移除歌曲
+        playlist.removeSong(song);
+        
+        // 保存更新后的歌单
+        playlistRepository.save(playlist);
     }
 
     @Override
     @Transactional
     public void deletePlaylist(Long playlistId, String username) {
-        // TODO: 实现删除歌单
-        // [Challenge] 需要检查用户是否有权限操作此歌单
-        throw new UnsupportedOperationException("待实现");
+        Playlist playlist = playlistRepository.findById(playlistId)
+                .orElseThrow(() -> new ResourceNotFoundException("Playlist not found with id: " + playlistId));
+        
+        // 检查用户是否有权限操作此歌单
+        checkPermission(playlist, username);
+        
+        // 删除歌单
+        playlistRepository.delete(playlist);
     }
 
     // ========== Advanced 方法 ==========
 
     @Override
     public List<PlaylistDTO> searchPlaylists(String keyword) {
-        // TODO [Advanced]: 实现按关键字搜索歌单
-        throw new UnsupportedOperationException("待实现");
+        List<Playlist> playlists = playlistRepository.findByNameContainingIgnoreCase(keyword);
+        return playlists.stream()
+                .map(this::toDTO)
+                .collect(Collectors.toList());
     }
 
     @Override
     @Transactional
     public PlaylistDTO copyPlaylist(Long playlistId, String newName, String username) {
-        // TODO [Advanced]: 实现复制歌单
-        throw new UnsupportedOperationException("待实现");
+        Playlist originalPlaylist = playlistRepository.findById(playlistId)
+                .orElseThrow(() -> new ResourceNotFoundException("Playlist not found with id: " + playlistId));
+        
+        User currentUser = userRepository.findByUsername(username)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found with username: " + username));
+        
+        // 创建新歌单
+        Playlist newPlaylist = new Playlist(newName, currentUser);
+        
+        // 复制所有歌曲
+        originalPlaylist.getSongs().forEach(song -> {
+            Song copiedSong = new Song(song.getTitle(), song.getArtist(), song.getDurationInSeconds());
+            newPlaylist.addSong(copiedSong);
+        });
+        
+        // 保存新歌单
+        Playlist savedPlaylist = playlistRepository.save(newPlaylist);
+        
+        return toDTO(savedPlaylist);
     }
 
     // ========== 辅助方法 ==========
@@ -99,16 +159,28 @@ public class PlaylistServiceImpl implements PlaylistService {
      * 将 Playlist 实体转换为 DTO
      */
     private PlaylistDTO toDTO(Playlist playlist) {
-        // TODO: 实现实体到 DTO 的转换
-        throw new UnsupportedOperationException("待实现");
+        List<SongDTO> songDTOs = playlist.getSongs().stream()
+                .map(this::toSongDTO)
+                .collect(Collectors.toList());
+        
+        return new PlaylistDTO(
+                playlist.getId(),
+                playlist.getName(),
+                playlist.getOwner().getUsername(),
+                songDTOs
+        );
     }
 
     /**
      * 将 Song 实体转换为 DTO
      */
     private SongDTO toSongDTO(Song song) {
-        // TODO: 实现实体到 DTO 的转换
-        throw new UnsupportedOperationException("待实现");
+        return new SongDTO(
+                song.getId(),
+                song.getTitle(),
+                song.getArtist(),
+                song.getDurationInSeconds()
+        );
     }
 
     /**
@@ -116,7 +188,15 @@ public class PlaylistServiceImpl implements PlaylistService {
      * 规则：歌单所有者或管理员可以操作
      */
     private void checkPermission(Playlist playlist, String username) {
-        // TODO [Challenge]: 实现权限检查
-        // 如果无权限，抛出 UnauthorizedException
+        User currentUser = userRepository.findByUsername(username)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found with username: " + username));
+        
+        // 检查是否是歌单所有者或管理员
+        boolean isOwner = playlist.getOwner().getUsername().equals(username);
+        boolean isAdmin = currentUser.getRole().equals("ROLE_ADMIN");
+        
+        if (!isOwner && !isAdmin) {
+            throw new UnauthorizedException("You don't have permission to access this playlist");
+        }
     }
 }

src/main/resources/application.properties

@@ -28,4 +28,5 @@ jwt.secret=your-secret-key-here-should-be-at-least-256-bits-long-for-hs256
 jwt.expiration=86400000
 
 # Server
-server.port=8080
+server.port=8081
+server.address=127.0.0.1