实现点赞功能

1.util包

在util包中添加RedisKeyUtil类。

package com.gerrard.community.util;

public class RedisKeyUtil {

    private static final String SPLIT = ":";
    private static final String PREFIX_ENTITY_LIKE = "like:entity";

    // 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;
    }

}

2.service层

添加LikeService类。

package com.gerrard.community.service;

import com.gerrard.community.util.RedisKeyUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;

@Service
public class LikeService {

    @Autowired
    private RedisTemplate redisTemplate;

    // 点赞
    //    (from->to  userId给entityUserId点赞)
    public void like(int userId, int entityType, int entityId) {
        String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
        boolean isMember = redisTemplate.opsForSet().isMember(entityLikeKey, userId);
        if (isMember) {
            redisTemplate.opsForSet().remove(entityLikeKey, userId);
        } else {
            redisTemplate.opsForSet().add(entityLikeKey, userId);
        }
    }

    // 查询某实体点赞的数量
    public long findEntityLikeCount(int entityType, int entityId) {
        String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
        return redisTemplate.opsForSet().size(entityLikeKey);
    }

    // 查询某人对某实体的点赞状态
    public int findEntityLikeStatus(int userId, int entityType, int entityId) {
        String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
        return redisTemplate.opsForSet().isMember(entityLikeKey, userId) ? 1 : 0;
    }

}

3.controller层

添加LikeController类，异步请求无法被拦截？

package com.gerrard.community.controller;

import com.gerrard.community.entity.User;
import com.gerrard.community.service.LikeService;
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;

import java.util.HashMap;
import java.util.Map;

@Controller
public class LikeController {

    @Autowired
    private LikeService likeService;

    @Autowired
    private HostHolder hostHolder;

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

        // 点赞
        likeService.like(user.getId(), entityType, entityId);

        // 数量
        long likeCount = likeService.findEntityLikeCount(entityType, entityId);
        // 状态
        int likeStatus = likeService.findEntityLikeStatus(user.getId(), entityType, entityId);
        // 返回的结果
        Map<String, Object> map = new HashMap<>();
        map.put("likeCount", likeCount);
        map.put("likeStatus", likeStatus);

        return CommunityUtil.getJSONString(0, null, map);
    }

}

用户在discuss-detail.html中点赞后，发送/like ajax异步请求【Restful风格和非Restful风格】，在redis数据库中保存点赞信息，再获取帖子或评论的点赞数量，用户针对帖子或评论的点赞状态，返回结果进行页面的增量更新。

例：id为154的用户给id为275的帖子点赞后，redis中存储如下键值对：

like:entity:entityType:entityId -> set(userId)
like:entity:1:275->{154}

DiscussPostController类和HomeController类中添加查询点赞数量相关代码。

package com.gerrard.community.controller;

import com.gerrard.community.entity.Comment;
import com.gerrard.community.entity.DiscussPost;
import com.gerrard.community.entity.Page;
import com.gerrard.community.entity.User;
import com.gerrard.community.service.CommentService;
import com.gerrard.community.service.DiscussPostService;
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.springframework.beans.factory.annotation.Autowired;
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.bind.annotation.ResponseBody;

import java.util.*;

@Controller
@RequestMapping("/discuss")
public class DiscussPostController implements CommunityConstant {

    @Autowired
    private DiscussPostService discussPostService;

    @Autowired
    private HostHolder hostHolder;

    @Autowired
    private UserService userService;

    @Autowired
    private CommentService commentService;

    @Autowired
    private LikeService likeService;

    @RequestMapping(path = "/add", method = RequestMethod.POST)
    @ResponseBody
    public String addDiscussPost(String title, String content) {
        User user = hostHolder.getUser();
        if (user == null) {
            return CommunityUtil.getJSONString(403, "你还没有登录哦!");
        }

        DiscussPost post = new DiscussPost();
        post.setUserId(user.getId());
        post.setTitle(title);
        post.setContent(content);
        post.setCreateTime(new Date());
        discussPostService.addDiscussPost(post);

        // 报错的情况,将来统一处理.
        return CommunityUtil.getJSONString(0, "发布成功!");
    }

    @RequestMapping(path = "/detail/{discussPostId}", method = RequestMethod.GET)
    public String getDiscussPost(@PathVariable("discussPostId") int discussPostId, Model model, Page page) {
        // 帖子
        DiscussPost post = discussPostService.findDiscussPostById(discussPostId);
        model.addAttribute("post", post);
        // 作者
        User user = userService.findUserById(post.getUserId());
        model.addAttribute("user", user);
        // 点赞数量
        long likeCount = likeService.findEntityLikeCount(ENTITY_TYPE_POST, discussPostId);
        model.addAttribute("likeCount", likeCount);
        // 点赞状态
        int likeStatus = hostHolder.getUser() == null ? 0 :
                likeService.findEntityLikeStatus(hostHolder.getUser().getId(), ENTITY_TYPE_POST, discussPostId);
        model.addAttribute("likeStatus", likeStatus);

        // 评论分页信息
        page.setLimit(5);
        page.setPath("/discuss/detail/" + discussPostId);
        page.setRows(post.getCommentCount());

        // 评论: 给帖子的评论
        // 回复: 给评论的评论
        // 评论列表
        List<Comment> commentList = commentService.findCommentsByEntity(
                ENTITY_TYPE_POST, post.getId(), page.getOffset(), page.getLimit());
        // 评论VO列表
        List<Map<String, Object>> commentVoList = new ArrayList<>();
        if (commentList != null) {
            for (Comment comment : commentList) {
                // 评论VO
                Map<String, Object> commentVo = new HashMap<>();
                // 评论
                commentVo.put("comment", comment);
                // 作者
                commentVo.put("user", userService.findUserById(comment.getUserId()));
                // 点赞数量
                likeCount = likeService.findEntityLikeCount(ENTITY_TYPE_COMMENT, comment.getId());
                commentVo.put("likeCount", likeCount);
                // 点赞状态
                likeStatus = hostHolder.getUser() == null ? 0 :
                        likeService.findEntityLikeStatus(hostHolder.getUser().getId(), ENTITY_TYPE_COMMENT, comment.getId());
                commentVo.put("likeStatus", likeStatus);

                // 回复列表
                List<Comment> replyList = commentService.findCommentsByEntity(
                        ENTITY_TYPE_COMMENT, comment.getId(), 0, Integer.MAX_VALUE);
                // 回复VO列表
                List<Map<String, Object>> replyVoList = new ArrayList<>();
                if (replyList != null) {
                    for (Comment reply : replyList) {
                        Map<String, Object> replyVo = new HashMap<>();
                        // 回复
                        replyVo.put("reply", reply);
                        // 作者
                        replyVo.put("user", userService.findUserById(reply.getUserId()));
                        // 回复目标
                        User target = reply.getTargetId() == 0 ? null : userService.findUserById(reply.getTargetId());
                        replyVo.put("target", target);
                        // 点赞数量
                        likeCount = likeService.findEntityLikeCount(ENTITY_TYPE_COMMENT, reply.getId());
                        replyVo.put("likeCount", likeCount);
                        // 点赞状态
                        likeStatus = hostHolder.getUser() == null ? 0 :
                                likeService.findEntityLikeStatus(hostHolder.getUser().getId(), ENTITY_TYPE_COMMENT, reply.getId());
                        replyVo.put("likeStatus", likeStatus);

                        replyVoList.add(replyVo);
                    }
                }
                commentVo.put("replys", replyVoList);

                // 回复数量
                int replyCount = commentService.findCommentCount(ENTITY_TYPE_COMMENT, comment.getId());
                commentVo.put("replyCount", replyCount);

                commentVoList.add(commentVo);
            }
        }

        model.addAttribute("comments", commentVoList);

        return "/site/discuss-detail";
    }

}

package com.gerrard.community.controller;

import com.gerrard.community.entity.DiscussPost;
import com.gerrard.community.entity.Page;
import com.gerrard.community.entity.User;
import com.gerrard.community.service.DiscussPostService;
import com.gerrard.community.service.LikeService;
import com.gerrard.community.service.UserService;
import com.gerrard.community.util.CommunityConstant;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Controller
public class HomeController implements CommunityConstant {

    @Autowired
    private DiscussPostService discussPostService;

    @Autowired
    private UserService userService;

    @Autowired
    private LikeService likeService;

    @RequestMapping(path = "/index", method = RequestMethod.GET)
    public String getIndexPage(Model model, Page page) {
        // 方法调用钱,SpringMVC会自动实例化Model和Page,并将Page注入Model.
        // 所以,在thymeleaf中可以直接访问Page对象中的数据.
        page.setRows(discussPostService.findDiscussPostRows(0));
        page.setPath("/index");

        List<DiscussPost> list = discussPostService.findDiscussPosts(0, page.getOffset(), page.getLimit());
        List<Map<String, Object>> discussPosts = new ArrayList<>();
        if (list != null) {
            for (DiscussPost post : list) {
                Map<String, Object> map = new HashMap<>();
                map.put("post", post);
                User user = userService.findUserById(post.getUserId());
                map.put("user", user);

                long likeCount = likeService.findEntityLikeCount(ENTITY_TYPE_POST, post.getId());
                map.put("likeCount", likeCount);

                discussPosts.add(map);
            }
        }
        model.addAttribute("discussPosts", discussPosts);
        return "/index";
    }

    @RequestMapping(path = "/error", method = RequestMethod.GET)
    public String getErrorPage() {
        return "/error/500";
    }

}

4.view层

index.html：

discuss-detail.html:

discuss.js:

function like(btn, entityType, entityId) {
    $.post(
        CONTEXT_PATH + "/like",
        {"entityType":entityType,"entityId":entityId},
        function(data) {
            data = $.parseJSON(data);
            if(data.code == 0) {
                $(btn).children("i").text(data.likeCount);
                $(btn).children("b").text(data.likeStatus==1?'已赞':"赞");
            } else {
                alert(data.msg);
            }
        }
    );
}s

5.功能测试

查看数据库：

redis数据库查询：