修改重复关注的问题

src/main/java/cn/meteor/beyondclouds/modules/user/service/IUserBlacklistService.java

 package cn.meteor.beyondclouds.modules.user.service;
 
 import cn.meteor.beyondclouds.modules.user.entity.UserBlacklist;
+import cn.meteor.beyondclouds.modules.user.exception.UserServiceException;
 import com.baomidou.mybatisplus.extension.service.IService;
 
 /**
@@ -18,5 +19,5 @@ public interface IUserBlacklistService extends IService<UserBlacklist> {
      * @param blackeId
      * @param userId
      */
-    void blacklist(String blackeId, String userId);
+    void blacklist(String blackeId, String userId) throws UserServiceException;
 }

src/main/java/cn/meteor/beyondclouds/modules/user/service/impl/UserBlacklistServiceImpl.java

 package cn.meteor.beyondclouds.modules.user.service.impl;
 
 import cn.meteor.beyondclouds.modules.user.entity.UserBlacklist;
+import cn.meteor.beyondclouds.modules.user.enums.UserErrorCode;
+import cn.meteor.beyondclouds.modules.user.exception.UserServiceException;
 import cn.meteor.beyondclouds.modules.user.mapper.UserBlacklistMapper;
 import cn.meteor.beyondclouds.modules.user.service.IUserBlacklistService;
+import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
 import org.springframework.stereotype.Service;
 
@@ -23,7 +26,15 @@ public class UserBlacklistServiceImpl extends ServiceImpl<UserBlacklistMapper, U
      * @param userId
      */
     @Override
-    public void blacklist(String blackedId, String userId) {
+    public void blacklist(String blackedId, String userId) throws UserServiceException {
+
+        QueryWrapper<UserBlacklist> myBlackListQueryWrapper = new QueryWrapper<>();
+        myBlackListQueryWrapper.eq("user_id", userId);
+        myBlackListQueryWrapper.eq("blacked_id", blackedId);
+
+        if(null != getOne(myBlackListQueryWrapper)){
+            throw new UserServiceException(UserErrorCode.USER_ALREADY_BLACKED);
+        }
         UserBlacklist userBlacklist = new UserBlacklist();
         userBlacklist.setBlackedId(blackedId);
         userBlacklist.setUserId(userId);