点赞功能详解

爱被打了一巴掌 2022-03-16 03:42 321阅读 0赞

###  点赞功能详解 ###

先讲讲点赞功能的实现。  
首先，你得为点赞功能建立一个表，表里需要记录点赞的topic的ID,已经点赞的人的id.  
对应的实体类如下：

package com.example.demo.domain;
    
    import javax.persistence.*;
    import java.io.Serializable;
    import java.util.Date;
    
    /** * @ClassName Praise * @Description TODO * @Auther ydc * @Date 2019/1/25 14:40 * @Version 1.0 **/
    @Entity
    @Table(name = "praise")
    /** * 点赞 */
    public class Praise extends BaseDomain implements Serializable { 
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "praise_id")
        private int praiseId;
    
    
        @Column(name = "topic_id")
        private int topicId;//被点赞的话题
    
        @Column(name = "user_id")
        private int userId;//点赞人id
    
        @Column(name = "praise_time")
        private Date praiseTime;//点赞时间
    
        public int getPraiseId() { 
            return praiseId;
        }
    
        public int getTopicId() { 
            return topicId;
        }
    
        public int getUserId() { 
            return userId;
        }
    
        public Date getPraiseTime() { 
            return praiseTime;
        }
    
        public void setPraiseId(int praiseId) { 
            this.praiseId = praiseId;
        }
    
        public void setTopicId(int topicId) { 
            this.topicId = topicId;
        }
    
        public void setUserId(int userId) { 
            this.userId = userId;
        }
    
        public void setPraiseTime(Date praiseTime) { 
            this.praiseTime = praiseTime;
        }
    
        public Praise() { 
        }
    
        public Praise(int topicId, int userId, Date praiseTime) { 
            this.topicId = topicId;
            this.userId = userId;
            this.praiseTime = praiseTime;
        }
    }

与点赞对应的必然是取消点赞，也就是说前端必须有两个按钮，一个是点赞，另一个是取消点赞，并且这两个按钮只能出现一个。先判断你有没有给这个文章点赞，如果你已经点赞了，那么就给你取消点赞的按钮，反之亦然。  
点赞以后，前端通过ajax将点赞信息发送到后端，后端保存下点赞信息并且修改文章的点赞次数即可。

注意下面js的写法

后端

@RequestMapping("topic/like/{topicId}")
        public ResponseData changePraise(HttpServletRequest request, @PathVariable("topicId") int topicId){ 
            System.out.println(111);
            try { 
                User user = getSessionUser(request);
                praiseServiceImp.like(topicId,user.getUserId());//完成修改
            }
            catch (Exception e){ 
                System.err.println("有错误");
            }
            return new ResponseData(ExceptionMsg.SUCCESS);
        }

@Override
        public void like(int topicId, int userId) { 
            Praise praise = praiseDao.findByUserIdAndTopicId(userId,topicId);
            Topic topic = topicDao.findByTopicId(topicId);
            if(praise==null){ 
                praise = new Praise(topicId,userId,new Date());
                praiseDao.save(praise);//先保存点赞信息
                topicDao.updatePraiseByTopicId(topic.getPraise()+1,topicId);//+1操作
            }
            else{ 
                praiseDao.deleteByPraiseId(praise.getPraiseId());
                topicDao.updatePraiseByTopicId(topic.getPraise()-1,topicId);//-1操作
            }
        }

[添加链接描述][Link 1]

[项目演示][Link 2]

[Link 1]: https://github.com/yangdongchao/springboot
[Link 2]: http://www.ydc98.club:443/