Web project (3) —— Realize the like function

content:

1. Implementation overview

2. jedis use

3. JedisAdapter - wraps basic jedis methods

4. RedisKeyUtil-Generated redisKey

5.LikeService-business implementation

6.LikeController-front-end interaction

7.HomeController

 

1. Implementation overview

Why should the like function be taken out separately, because the like is a function with very frequent data exchange. If the mysql database is used to store data, the database pressure will be great, so the memory -based redis database is used to implement it.

Please refer to the installation and simple use of redis: https://www.cnblogs.com/fyboke/p/6264922.html

The redis database is a key-value database that supports many types of stored values , including string (string), list (linked list), set (collection), zset (sorted set -- ordered set) and hash ( hash type).

Therefore, to implement the like function, we only need to use the key to store which news we are currently in, and use the value to store a set of users who like this news.

 

2. jedis use

Introduction to jedis: jedis is the driver jar package of the java language of the redis database, which is used to operate the redis database, which encapsulates the basic operations of redis. Similar to the mysql-jdbc connection bridge.

You need to add jedis dependencies to the pom.xml file:

		<dependency>
			<groupId>redis.clients</groupId>
			<artifactId>jedis</artifactId>
			<version>2.8.0</version>
		</dependency>

3.jedisAdapter

This class is annotated with @Service to wrap basic jedis operations. Mainly sadd, srem and sisremember.

package com.nowcoder.util;

import com.alibaba.fastjson.JSON;
import com.nowcoder.async.EventModel;
import com.nowcoder.async.EventType;
import com.nowcoder.controller.IndexController;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.ExceptionHandler;
import redis.clients.jedis.*;

import java.util.List;

/**
 * Created by nowcoder on 2016/7/13.
 */
@Service
public class JedisAdapter implements InitializingBean {
    private static final Logger logger = LoggerFactory.getLogger(JedisAdapter.class);

    private Jedis jedis = null;
    private JedisPool pool = null;

    @Override
    public void afterPropertiesSet() throws Exception {
        //在初始化之后初始化pool
        //jedis = new Jedis("localhost");//直接使用jedis
        pool = new JedisPool("localhost", 6379);//使用jedis池
    }

    private Jedis getJedis() {
        //return jedis;
        return pool.getResource();
    }

    public long sadd(String key, String value) {//将k-v存入redis的set中
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            return jedis.sadd(key, value);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
            return 0;
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

    public long srem(String key, String value) {//将k-v从redis的set中移除
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            return jedis.srem(key, value);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
            return 0;
        } finally {
            if (jedis != null) {
                jedis.close();//使用完池中的jedis，即使关闭
            }
        }
    }

    public boolean sismember(String key, String value) {//判断set中是否含有目标k-v
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            return jedis.sismember(key, value);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
            return false;
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

    public long scard(String key) {//返回set中有多少个元素
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            return jedis.scard(key);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
            return 0;
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

//**************************************************
    public void setex(String key, String value) {
        // 验证码, 防机器注册，记录上次注册时间，有效期3天
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            jedis.setex(key, 10, value);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

    public long lpush(String key, String value) {
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            return jedis.lpush(key, value);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
            return 0;
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

    public List<String> brpop(int timeout, String key) {
        Jedis jedis = null;
        try {
            jedis = pool.getResource();
            return jedis.brpop(timeout, key);
        } catch (Exception e) {
            logger.error("发生异常" + e.getMessage());
            return null;
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

    public void setObject(String key, Object obj) {
        set(key, JSON.toJSONString(obj));
    }

    public <T> T getObject(String key, Class<T> clazz) {
        String value = get(key);
        if (value != null) {
            return JSON.parseObject(value, clazz);
        }
        return null;
    }
}

4.RedisKeyUtil

As mentioned earlier, kv is used to store likes, so for each news, we must have a specific key. This class is used to generate this key.

package com.nowcoder.util;

/**
 * Created by nowcoder on 2016/7/13.
 */
public class RedisKeyUtil {
    private static String SPLIT = ":";
    private static String BIZ_LIKE = "LIKE";
    private static String BIZ_DISLIKE = "DISLIKE";
    private static String BIZ_EVENT = "EVENT";

    public static String getEventQueueKey() {
        return BIZ_EVENT;
    }

    //虽然这里只是实现了对news的点赞功能，但是为了增强代码的可复用性，int entityId, int entityType可以表示某一个元素而不单是news
    public static String getLikeKey(int entityId, int entityType) {
        return BIZ_LIKE + SPLIT + String.valueOf(entityType) + SPLIT + String.valueOf(entityId);
    }

    public static String getDisLikeKey(int entityId, int entityType) {
        return BIZ_DISLIKE + SPLIT + String.valueOf(entityType) + SPLIT + String.valueOf(entityId);
    }
}

5.LikeService

This class implements the functions of likes and dislikes by calling the methods in jedisAdapter.

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 nowcoder on 2016/7/13.
 */
@Service
public class LikeService {
    @Autowired
    JedisAdapter jedisAdapter;

    //判断某用户对某个元素的赞踩状态，喜欢返回1，不喜欢返回-1，否则返回0
    public int getLikeStatus(int userId, int entityType, int entityId) {
        String likeKey = RedisKeyUtil.getLikeKey(entityId, entityType);
        if(jedisAdapter.sismember(likeKey, String.valueOf(userId))) {
            return 1;
        }
        String disLikeKey = RedisKeyUtil.getDisLikeKey(entityId, entityType);
        return jedisAdapter.sismember(disLikeKey, String.valueOf(userId)) ? -1 : 0;
    }

    //实现赞功能
    public long like(int userId, int entityType, int entityId) {
        // 在喜欢集合里增加
        String likeKey = RedisKeyUtil.getLikeKey(entityId, entityType);
        jedisAdapter.sadd(likeKey, String.valueOf(userId));
        // 从反对里删除
        String disLikeKey = RedisKeyUtil.getDisLikeKey(entityId, entityType);
        jedisAdapter.srem(disLikeKey, String.valueOf(userId));
        return jedisAdapter.scard(likeKey);
    }

    //实现踩功能
    public long disLike(int userId, int entityType, int entityId) {
        // 在反对集合里增加
        String disLikeKey = RedisKeyUtil.getDisLikeKey(entityId, entityType);
        jedisAdapter.sadd(disLikeKey, String.valueOf(userId));
        // 从喜欢里删除
        String likeKey = RedisKeyUtil.getLikeKey(entityId, entityType);
        jedisAdapter.srem(likeKey, String.valueOf(userId));
        return jedisAdapter.scard(likeKey);
    }
}

6.LikeController

Get the newsId from the front-end, get the userId from the hostHolder, and complete the front-end and back-end interaction.

package com.nowcoder.controller;

import com.nowcoder.async.EventModel;
import com.nowcoder.async.EventProducer;
import com.nowcoder.async.EventType;
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.apache.ibatis.annotations.Param;
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.ResponseBody;

/**
 * Created by nowcoder on 2016/7/13.
 */
@Controller
public class LikeController {
    @Autowired
    LikeService likeService;

    @Autowired
    HostHolder hostHolder;//以便获取登录用户

    @Autowired
    NewsService newsService;

    @Autowired
    EventProducer eventProducer;//异步

    @RequestMapping(path = {"/like"}, method = {RequestMethod.GET, RequestMethod.POST})
    @ResponseBody
    public String like(@Param("newId") int newsId) {

        //调用喜欢功能
        long likeCount = likeService.like(hostHolder.getUser().getId(), EntityType.ENTITY_NEWS, newsId);
        // 更新mysql数据库的喜欢数
        News news = newsService.getById(newsId);
        newsService.updateLikeCount(newsId, (int) likeCount);

        //异步队列，以后说
        eventProducer.fireEvent(new EventModel(EventType.LIKE)
                .setEntityOwnerId(news.getUserId())
                .setActorId(hostHolder.getUser().getId()).setEntityId(newsId));

        //通过json串，将赞数量返回前端
        return ToutiaoUtil.getJSONString(0, String.valueOf(likeCount));
    }


    @RequestMapping(path = {"/dislike"}, method = {RequestMethod.GET, RequestMethod.POST})
    @ResponseBody
    public String dislike(@Param("newId") int newsId) {
        long likeCount = likeService.disLike(hostHolder.getUser().getId(), EntityType.ENTITY_NEWS, newsId);
        // 更新喜欢数
        newsService.updateLikeCount(newsId, (int) likeCount);
        return ToutiaoUtil.getJSONString(0, String.valueOf(likeCount));
    }
}

7.HomeController

Because on the home page, if a user likes, then the effect of the "Like" button displayed on it should be in the "pressed" state, so the homeController also needs to get the currently logged in user, and read from the redis set whether it contains the userId.

NewsController is similar.