实现关注、取消关注功能

1.util包

RedisKeyUtil类中添加getFollowerKey方法。

package com.gerrard.community.util;

public class RedisKeyUtil {

    private static final String SPLIT = ":";
    private static final String PREFIX_ENTITY_LIKE = "like:entity";
    private static final String PREFIX_USER_LIKE = "like:user";
    private static final String PREFIX_FOLLOWEE = "followee";
    private static final String PREFIX_FOLLOWER = "follower";

   //某个实体的赞
    //like:entity:【entityType:entityId】->【set(userId)】
    public static String getEntityLikeKey(int entityType, int entityId) {
        return PREFIX_ENTITY_LIKE + SPLIT + entityType + SPLIT + entityId;
    }

     //某个用户的赞
    //like:user:【userId】->int
    public static String getUserLikeKey(int userId) {
        return PREFIX_USER_LIKE + SPLIT + userId;
    }

     //某个用户关注的实体（键：用户Id，值：实体Id）
    //followee:【userId:entityType】->zset(entityId,now)
    public static String getFolloweeKey(int userId, int entityType) {
        return PREFIX_FOLLOWEE + SPLIT + userId + SPLIT + entityType;
    }
   

  //某个实体拥有的粉丝（键：实体Id，值：用户Id)
    //follower:【entityType:entityId】->zset(userId,now)
    public static String getFollowerKey(int entityType, int entityId) {
        return PREFIX_FOLLOWER + SPLIT + entityType + SPLIT + entityId;
    }
    //entityType不可以删除，userId和entityId值会有重复，需要借助entityType构成键的一部分加以区分，【不对】
    //entityType不可以删除，Id值相同的情况下，需要借助entityType以示区分

}

CommunityConstant类中添加实体类型：用户字段。

	/**
     * 实体类型：用户
     */
    int ENTITY_TYPE_USER=3;

2.service层

添加FollowerService类。

package com.gerrard.community.service;

import com.nowcoder.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;

@Service
public class FollowService {

    @Autowired
    private RedisTemplate redisTemplate;

    //可以将follow好unfollow整合到一块
    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  用户关注的实体
    public boolean hasFollowed(int userId, int entityType, int entityId) {
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().score(followeeKey, entityId) != null;
    }

}

3.controller层

添加FollowerController类。

以关注为例：在profile.html点击关注ta按钮，发送/follow ajax请求。

1.先查询到登录用户；

2.再在redis数据库中添加相关键值对；【涉及到多表操作，开启事务操作】

例：id为15z的用户关注了id为152的用户，则redis数据库中插入以下键值对：

//followee:【userId:entityType】->zset(entityId,now)
 //follower:【entityType:entityId】->zset(userId,now)
 
 followee:【154:3】->{152,now}
 follower:【3:152】->{154,now}

3.最后返回已关注提示信息。

package com.gerrard.community.controller;

import com.gerrard.community.entity.User;
import com.gerrard.community.service.FollowService;
import com.gerrard.community.util.CommunityUtil;
import com.gerrard.community.util.HostHolder;
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;

@Controller
public class FollowController {

    @Autowired
    private FollowService followService;

    @Autowired
    private HostHolder hostHolder;

    @RequestMapping(path = "/follow", method = RequestMethod.POST)
    @ResponseBody
    public String follow(int entityType, int entityId) {
        User user = hostHolder.getUser();

        followService.follow(user.getId(), entityType, entityId);

        return CommunityUtil.getJSONString(0, "已关注!");
    }

    @RequestMapping(path = "/unfollow", method = RequestMethod.POST)
    @ResponseBody
    public String unfollow(int entityType, int entityId) {
        User user = hostHolder.getUser();

        followService.unfollow(user.getId(), entityType, entityId);

        return CommunityUtil.getJSONString(0, "已取消关注!");
    }

}

UserController中对getProfilePage方法进行重构。

用户在index页面访问profile页面时，先获取查看用户信息的该用户实体，接着查询redis数据库，调用likeService查询点赞数量，调用followService查询关注数量和粉丝数量，是否已关注作者，并返回至profile页面。

package com.gerrard.community.controller;

import com.gerrard.community.annotation.LoginRequired;
import com.gerrard.community.entity.User;
import com.gerrard.community.service.FollowService;
import com.gerrard.community.service.LikeService;
import com.gerrard.community.service.UserService;
import com.gerrard.community.util.CommunityConstant;
import com.gerrard.community.util.CommunityUtil;
import com.gerrard.community.util.HostHolder;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

@Controller
@RequestMapping("/user")
public class UserController implements CommunityConstant {

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

    @Value("${community.path.upload}")
    private String uploadPath;

    @Value("${community.path.domain}")
    private String domain;

    @Value("${server.servlet.context-path}")
    private String contextPath;

    @Autowired
    private UserService userService;

    @Autowired
    private HostHolder hostHolder;

    @Autowired
    private LikeService likeService;

    @Autowired
    private FollowService followService;

    @LoginRequired
    @RequestMapping(path = "/setting", method = RequestMethod.GET)
    public String getSettingPage() {
        return "/site/setting";
    }

    @LoginRequired
    @RequestMapping(path = "/upload", method = RequestMethod.POST)
    public String uploadHeader(MultipartFile headerImage, Model model) {
        if (headerImage == null) {
            model.addAttribute("error", "您还没有选择图片!");
            return "/site/setting";
        }

        String fileName = headerImage.getOriginalFilename();
        String suffix = fileName.substring(fileName.lastIndexOf("."));
        if (StringUtils.isBlank(suffix)) {
            model.addAttribute("error", "文件的格式不正确!");
            return "/site/setting";
        }

        // 生成随机文件名
        fileName = CommunityUtil.generateUUID() + suffix;
        // 确定文件存放的路径
        File dest = new File(uploadPath + "/" + fileName);
        try {
            // 存储文件
            headerImage.transferTo(dest);
        } catch (IOException e) {
            logger.error("上传文件失败: " + e.getMessage());
            throw new RuntimeException("上传文件失败,服务器发生异常!", e);
        }

        // 更新当前用户的头像的路径(web访问路径)
        // http://localhost:8080/community/user/header/xxx.png
        User user = hostHolder.getUser();
        String headerUrl = domain + contextPath + "/user/header/" + fileName;
        userService.updateHeader(user.getId(), headerUrl);

        return "redirect:/index";
    }

    @RequestMapping(path = "/header/{fileName}", method = RequestMethod.GET)
    public void getHeader(@PathVariable("fileName") String fileName, HttpServletResponse response) {
        // 服务器存放路径
        fileName = uploadPath + "/" + fileName;
        // 文件后缀
        String suffix = fileName.substring(fileName.lastIndexOf("."));
        // 响应图片
        response.setContentType("image/" + suffix);
        try (
                FileInputStream fis = new FileInputStream(fileName);
                OutputStream os = response.getOutputStream();
        ) {
            byte[] buffer = new byte[1024];
            int b = 0;
            while ((b = fis.read(buffer)) != -1) {
                os.write(buffer, 0, b);
            }
        } catch (IOException e) {
            logger.error("读取头像失败: " + e.getMessage());
        }
    }

    // 个人主页
    @RequestMapping(path = "/profile/{userId}", method = RequestMethod.GET)
    public String getProfilePage(@PathVariable("userId") int userId, Model model) {
        User user = userService.findUserById(userId);
        if (user == null) {
            throw new RuntimeException("该用户不存在!");
        }

        // 用户
        model.addAttribute("user", user);
        // 点赞数量
        int likeCount = likeService.findUserLikeCount(userId);
        model.addAttribute("likeCount", likeCount);

        // 关注数量
        long followeeCount = followService.findFolloweeCount(userId, ENTITY_TYPE_USER);
        model.addAttribute("followeeCount", followeeCount);
        // 粉丝数量
        long followerCount = followService.findFollowerCount(ENTITY_TYPE_USER, userId);
        model.addAttribute("followerCount", followerCount);
        // 是否已关注
        boolean hasFollowed = false;
        if (hostHolder.getUser() != null) {
            hasFollowed = followService.hasFollowed(hostHolder.getUser().getId(), ENTITY_TYPE_USER, userId);
        }
        model.addAttribute("hasFollowed", hasFollowed);

        return "/site/profile";
    }

}

4.view层

profile.html：

动态展示数据:

profile.js:

为关注ta按钮绑定单击事件：发送ajax请求：

5.功能测试

Redis数据库查看：