7_1_Redis实现赞踩功能

一、实现需求

1. 登录账号以后，在首页home.html内可以点赞或者取消赞，只能点赞一次，点赞以后就不可再点赞；

   取消赞以后为0.

2 点开news以后也可以点赞或者取消赞。

二.具体实现

1  util包下写一个类似DAO的组件，组件类包括Jedis初始化，获取Jedis,Jedis的获取get,set,获取集合大小等操作。

package com.nowcoder.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

/**
 * Created by Administrator on 2017/5/1.
 */
@Service
public class JedisAdapter implements InitializingBean {

    private static final Logger logger = LoggerFactory.getLogger(JedisAdapter.class);

    private Jedis jedis = null;
    private JedisPool jedisPool = null;

    @Override
    public void afterPropertiesSet() throws Exception {
        //初始化
        jedisPool = new JedisPool("localhost", 6379);
    }

    //获取一个Jedis
    private Jedis getJedis(){
        try{
            jedis =  jedisPool.getResource();
        }catch (Exception e){
            logger.error("获取jedis失败！" + e.getMessage());
        }finally {
            if(jedis != null){
                jedis.close();
            }
        }
        return jedis;
    }

    /**
     * 获取Redis中集合中某个key值
     * @param key
     * @return
     */
    public String get(String key){
        Jedis jedis = null;
        try {
            jedis =  jedisPool.getResource();
            return jedis.get(key);
        }catch (Exception e){
            logger.error("Jedis get发生异常 " + e.getMessage());
            return null;
        }finally {
            if(jedis != null){
                jedis.close();
            }
        }
    }

    /**
     * 给Redis中Set集合中某个key值设值
     * @param key
     * @param value
     */
    public void set(String key, String value){
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            jedis.set(key, value);
        }catch (Exception e){
            logger.error("Jedis set 异常" + e.getMessage());
        }finally {
            if(jedis != null){
                jedis.close();
            }
        }
    }

    /**
     * 向Redis中Set集合添加值:点赞
     * @return
     */
    public long sadd(String key, String value){
        Jedis jedis = null;
        try{
            jedis =  jedisPool.getResource();
            return jedis.sadd(key, value);
        }catch (Exception e){
            logger.error("Jedis sadd 异常 ：" + e.getMessage());
            return 0;
        }finally {
            if (jedis != null){
                jedis.close();
            }
        }
    }

    /**
     * 移除：取消点赞
     * @param key
     * @param value
     * @return
     */
    public long srem(String key, String value){
        Jedis jedis = null;
        try{
            jedis =  jedisPool.getResource();
            return jedis.srem(key, value);
        }catch (Exception e){
            logger.error("Jedis srem 异常：" + e.getMessage());
            return 0;
        }finally {
            if (jedis != null){
                jedis.close();
            }
        }
    }

    /**
     *p判断key,value是否是集合中值
     * @param key
     * @param value
     * @return
     */
    public boolean sismember(String key, String value){
        Jedis jedis = null;
        try{
            jedis =  jedisPool.getResource();
            return jedis.sismember(key, value);
        }catch (Exception e){
            logger.error("Jedis sismember 异常：" + e.getMessage());
            return false;
        }finally {
            if (jedis != null){
                try{
                    jedis.close();
                }catch (Exception e){
                    logger.error("Jedis关闭异常" + e.getMessage());
                }
            }
        }
    }

    /**
     * 获取集合大小
     * @param key
     * @return
     */
    public long scard(String key){
        Jedis jedis = null;
        try{
            jedis =  jedisPool.getResource();
            return jedis.scard(key);
        }catch (Exception e){
            logger.error("Jedis scard 异常：" + e.getMessage());
            return 0;
        }finally {
            if (jedis != null){
                jedis.close();
            }
        }
    }













}

2 util包下写一个util工具类，实现点赞生成键key的值。

package com.nowcoder.util;

import org.springframework.stereotype.Service;

/**
 * Created by Administrator on 2017/5/1.
 */
public class RedisKeyUtil {

    private static String SPLIT = ":";
    private static String BIZ_LIKE = "LIKE";
    private static String BIZ_DISLIKE = "DISLIKE";

    /**
     * 产生key:如在newsId为2上的咨询点赞后会产生key: LIKE:ENTITY_NEWS:2
     * @param entityId
     * @param entityType
     * @return
     */
    public static String getLikeKey(int entityId, int entityType){
        return BIZ_LIKE + SPLIT + String.valueOf(entityType) + SPLIT + String.valueOf(entityId);
    }
    /**
     * 取消赞:如在newsId为2上的资讯取消点赞后会产生key: DISLIKE:ENTITY_NEWS:2
     * @param entityId
     * @param entityType
     * @return
     */
    public static String getDisLikeKey(int entityId, int entityType){
        return BIZ_DISLIKE + SPLIT + String.valueOf(entityType) + SPLIT + String.valueOf(entityId);
    }









}

3 Service包下写上一个判断点赞还是反对的方法，当点赞后将当前点赞用户id存入likeKey集合中，同时从disLikeKey中移除此id：

package com.nowcoder.service;

import com.nowcoder.util.JedisAdapter;
import com.nowcoder.util.RedisKeyUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * Created by Administrator on 2017/5/1.
 */
@Service
public class LikeService {

    @Autowired
    JedisAdapter jedisAdapter;

    /**
     * 判断是点赞还是点反对
     * @param userId
     * @param entityType
     * @param entityId
     * @return
     */
    public int getLikeStatus(int userId, int entityType, int entityId) {
        //根据当前用户的userid分别生成一个likeKey 和 disLikeKey,再分别判断这两个值是否在对应的Like集合中和disLikeKey集合中
        //比如如果在likeKey集合中，就返回一个1，否则返回-1
        String likeKey = RedisKeyUtil.getLikeKey(entityId, entityType);
        //判断值为userId 的用户是否在key为listKey 的集合中
        if(jedisAdapter.sismember(likeKey, String.valueOf(userId))){
            return 1;
        }
        String disLikeKey = RedisKeyUtil.getDisLikeKey(entityId, entityType);
        return jedisAdapter.sismember(disLikeKey, String.valueOf(userId)) ? -1: 0;
    }

    /**
     * 点赞：即当前用户点赞后，被点赞用户的like集合中就会加上一个该点赞的用户信息
     * @param userId
     * @param entityType
     * @param entityId
     * @return
     */
    public long like(int userId, int entityType, int entityId){
        //在当前news上点赞后获取key:   LIKE:ENTITY_NEWS:2
       String likeKey = RedisKeyUtil.getLikeKey(entityId, entityType);
       //在喜欢集合中添加当前操作用户的userId(即当前用户点赞后，被点赞用户的like集合中就会加上一个点赞的用户信息)
       jedisAdapter.sadd(likeKey, String.valueOf(userId));

       String disLikeKey = RedisKeyUtil.getDisLikeKey(entityId, entityType);
       jedisAdapter.srem(disLikeKey, String.valueOf(userId));

       //返回点赞数量
        return jedisAdapter.scard(likeKey);
    }

    /**
     * 反对 ：即当前用户点反对后，被点反对用户的like集合中就会加上一个该点反对的用户信息
     * @param userId
     * @param entityType
     * @param entityId
     * @return
     */
    public long disLike(int userId, int entityType, int entityId){

        //谁点击反对，谁就出现在key为dislikeKey的Set集合中
        String disLikeKey = RedisKeyUtil.getDisLikeKey(entityId, entityType);
        jedisAdapter.sadd(disLikeKey, String.valueOf(userId));

        //从赞中删除
        String likeKey = RedisKeyUtil.getLikeKey(entityId, entityType);
        jedisAdapter.srem(likeKey, String.valueOf(userId));

        return jedisAdapter.scard(likeKey);
    }













}

4 Controller: 调用LikeService，将当前用户id存入Redis的LikeKey集合中，并更新News表中 的like_count数量；对应的dislike也是一样。

package com.nowcoder.controller;

import com.nowcoder.model.EntityType;
import com.nowcoder.model.HostHolder;
import com.nowcoder.model.News;
import com.nowcoder.service.LikeService;
import com.nowcoder.service.NewsService;
import com.nowcoder.util.ToutiaoUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * Created by Administrator on 2017/5/1.
 */
@Controller
public class LikeController {

    @Autowired
    LikeService likeService;
    @Autowired
    NewsService newsService;
    @Autowired
    HostHolder hostHolder;

    @RequestMapping(path = {"/like"}, method = {RequestMethod.GET, RequestMethod.POST})
    @ResponseBody
    public String like(@RequestParam("newsId") int newsId){
        //在newsId 的资讯上加入当前用户
        long likeCount = likeService.like(hostHolder.getUser().getId(), EntityType.ENTITY_NEWS, newsId);

        //更新点赞数
        //News news = newsService.getById(newsId);
        newsService.updateLikeCount(newsId, (int)likeCount);

        return ToutiaoUtil.getJSONString(0, String.valueOf(likeCount));
    }

    @RequestMapping(path = {"/dislike"}, method = {RequestMethod.POST, RequestMethod.GET})
    @ResponseBody
    public String disLike(@RequestParam("newsId") int newsId){

        //点击反对：调用disLike,将当前点击反对的用户id从key为dislikeKey的集合中移除
        long likeCount = likeService.disLike(hostHolder.getUser().getId(), EntityType.ENTITY_NEWS, newsId);
        if(likeCount <= 0){
            likeCount = 0;
        }

        //更新喜欢数
        newsService.updateLikeCount(newsId, (int)likeCount);
        return ToutiaoUtil.getJSONString(0, String.valueOf(likeCount));
    }


}

5. NewsService:

  public int updateLikeCount(int newsId, int likeCount){
        return newsDao.updateLikeCount(newsId, likeCount);
    }

NewsDao:

   @Update({"update", TABLE_NAME, "set like_count=#{likeCount} where id=#{newsId}"})
    int updateLikeCount(@Param("newsId") int newsId, @Param("likeCount") int likeCount);

6. 同时HomeController中首页获取News上的点赞时，要加入判断。如果是未登录，点赞数全部为0；登录后就获取点赞的状态判断是点赞还是反对。

 if (localUserId != 0) {
                vo.set("like", likeService.getLikeStatus(localUserId, EntityType.ENTITY_NEWS, news.getId()));
            } else {
                vo.set("like", 0);
            }

7. NewsController中的获取News详情页也要加入这样的判断: