redis——实战关注

﹏ヽ暗。殇╰゛Y 2023-06-11 05:29 10阅读 0赞

效果：

![20191029142507534.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9mYW50aWFuenVvLmJsb2cuY3Nkbi5uZXQ_size_16_color_FFFFFF_t_70][]

思路：很好想，把自己的粉丝和自己关注的人都存起来（set即可），做增删改查。

package com.now.community.community.service;
    
    import com.now.community.community.entity.User;
    import com.now.community.community.util.CommunityConstant;
    import com.now.community.community.util.RedisKeyUtil;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.dao.DataAccessException;
    import org.springframework.data.redis.core.RedisOperations;
    import org.springframework.data.redis.core.RedisTemplate;
    import org.springframework.data.redis.core.SessionCallback;
    import org.springframework.stereotype.Service;
    
    import java.util.*;
    
    @Service
    public class FollowService implements CommunityConstant {
    
        @Autowired
        private RedisTemplate redisTemplate;
    
        @Autowired
        private UserService userService;
        public void follow(int userId, int entityType, int entityId) {
            redisTemplate.execute(new SessionCallback() {
                @Override
                public Object execute(RedisOperations operations) throws DataAccessException {
                    String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                    String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);
    
                    operations.multi();
    
                    operations.opsForZSet().add(followeeKey, entityId, System.currentTimeMillis());
                    operations.opsForZSet().add(followerKey, userId, System.currentTimeMillis());
    
                    return operations.exec();
                }
            });
        }
    
        public void unfollow(int userId, int entityType, int entityId) {
            redisTemplate.execute(new SessionCallback() {
                @Override
                public Object execute(RedisOperations operations) throws DataAccessException {
                    String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                    String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);
    
                    operations.multi();
    
                    operations.opsForZSet().remove(followeeKey, entityId);
                    operations.opsForZSet().remove(followerKey, userId);
    
                    return operations.exec();
                }
            });
        }
    
        // 查询关注的实体的数量
        public long findFolloweeCount(int userId, int entityType) {
            String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
            return redisTemplate.opsForZSet().zCard(followeeKey);
        }
    
        // 查询实体的粉丝的数量
        public long findFollowerCount(int entityType, int entityId) {
            String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);
            return redisTemplate.opsForZSet().zCard(followerKey);
        }
    
        // 查询当前用户是否已关注该实体
        public boolean hasFollowed(int userId, int entityType, int entityId) {
            String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
            return redisTemplate.opsForZSet().score(followeeKey, entityId) != null;
        }
    
        // 查询某用户关注的人
        public List<Map<String, Object>> findFollowees(int userId, int offset, int limit) {
            String followeeKey = RedisKeyUtil.getFolloweeKey(userId, ENTITY_TYPE_USER);
            Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followeeKey, offset, offset + limit - 1);
    
            if (targetIds == null) {
                return null;
            }
    
            List<Map<String, Object>> list = new ArrayList<>();
            for (Integer targetId : targetIds) {
                Map<String, Object> map = new HashMap<>();
                User user = userService.findUserById(targetId);
                map.put("user", user);
                Double score = redisTemplate.opsForZSet().score(followeeKey, targetId);
                map.put("followTime", new Date(score.longValue()));
                list.add(map);
            }
    
            return list;
        }
    
        // 查询某用户的粉丝
        public List<Map<String, Object>> findFollowers(int userId, int offset, int limit) {
            String followerKey = RedisKeyUtil.getFollowerKey(ENTITY_TYPE_USER, userId);
            Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followerKey, offset, offset + limit - 1);
    
            if (targetIds == null) {
                return null;
            }
    
            List<Map<String, Object>> list = new ArrayList<>();
            for (Integer targetId : targetIds) {
                Map<String, Object> map = new HashMap<>();
                User user = userService.findUserById(targetId);
                map.put("user", user);
                Double score = redisTemplate.opsForZSet().score(followerKey, targetId);
                map.put("followTime", new Date(score.longValue()));
                list.add(map);
            }
    
            return list;
        }
    }

[20191029142507534.png]: /images/20230531/63d2cbae29f645f18ab84e3077fe31e7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9mYW50aWFuenVvLmJsb2cuY3Nkbi5uZXQ_size_16_color_FFFFFF_t_70]: /images/20230531/34bf15d6b14148a6b906368e90c569a3.png