完成用户在线状态查询

src/main/java/com/bao/dating/controller/UserController.java

@@ -203,4 +203,15 @@ public class UserController {
         return Result.success(ResultCode.SUCCESS,"用户登录成功",userLoginVO);
     }
 
+    /**
+     * 判断用户是否在线
+     * @param userId 用户ID
+     * @return 用户是否在线
+     */
+    @GetMapping("/{userId}/online")
+    public Result<Boolean> isUserOnline(@PathVariable Long userId) {
+
+        boolean online = userService.isUserOnline(userId);
+        return Result.success(ResultCode.SUCCESS, "查询成功", online);
+    }
 }

src/main/java/com/bao/dating/service/UserService.java

@@ -92,4 +92,11 @@ public interface UserService {
      * @return 用户列表
      */
     List<UserInfoVO> findNearbyUsers(double lat,double lng,double  radiusKm);
+
+    /**
+     * 判断用户是否在线
+     * @param userId 用户ID
+     * @return 是否在线
+     */
+    boolean isUserOnline(Long userId);
 }

src/main/java/com/bao/dating/service/impl/UserServiceImpl.java

@@ -491,4 +491,23 @@ public class UserServiceImpl implements UserService {
         }
         return result;
     }
+
+    @Override
+    public boolean isUserOnline(Long userId) {
+        if (userId == null) {
+            return false;
+        }
+
+        // 1. 是否被封禁
+        String banKey = "user:ban:" + userId;
+        if (Boolean.TRUE.equals(redisTemplate.hasKey(banKey))) {
+            return false;
+        }
+
+        // 2. 是否存在登录 token
+        String tokenKey = "login:token:" + userId;
+        Boolean online = redisTemplate.hasKey(tokenKey);
+
+        return Boolean.TRUE.equals(online);
+    }
 }