Redis帖子相关功能实现 （发布笔记查看笔记点赞功能点赞排行榜）

Posted 2022-09-20 Perceus

(目录)

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帖子相关功能

1. 发布笔记

发布帖子

探店笔记类似点评网站的评价，往往是图文结合。对应的表有两个：

具体发布流程

1. 上传图片接口

@Slf4j
@RestController
@RequestMapping("upload")
public class UploadController 

    @PostMapping("blog")
    public Result uploadImage(@RequestParam("file") MultipartFile image) 
        try 
            // 获取原始文件名称
            String originalFilename = image.getOriginalFilename();
            // 生成新文件名
            String fileName = createNewFileName(originalFilename);
            // 保存文件
            image.transferTo(new File(SystemConstants.IMAGE_UPLOAD_DIR, fileName));
            // 返回结果
            log.debug("文件上传成功，", fileName);
            return Result.ok(fileName);
         catch (IOException e) 
            throw new RuntimeException("文件上传失败", e);
        
    

注意：

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2. 保存博文接口

@RestController
@RequestMapping("/blog")
public class BlogController 

    @Resource
    private IBlogService blogService;

    @PostMapping
    public Result saveBlog(@RequestBody Blog blog) 
        //获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUpdateTime(user.getId());
        //保存探店博文
        blogService.saveBlog(blog);
        //返回id
        return Result.ok(blog.getId());
    

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2. 查看探店笔记

实现代码：

    @Override
    public Result queryBlogById(Long id) 
        // 1.查询blog
        Blog blog = getById(id);
        if (blog == null) 
            return Result.fail("笔记不存在！");
        
        // 2.查询blog有关的用户
        queryBlogUser(blog);
        return Result.ok(blog);
    

    private void queryBlogUser(Blog blog) 
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    

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3. 点赞功能

初始代码

@GetMapping("/likes/id")
public Result queryBlogLikes(@PathVariable("id") Long id) 
    //修改点赞数量
    blogService.update().setSql("liked = liked +1 ").eq("id",id).update();
    return Result.ok();

问题分析：

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完善点赞功能

需求：

这里就不使用MySQL数据库建表那个逻辑，使用Redis

实现步骤：

为什么采用set集合：

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具体步骤：

@TableField(exist = false)
private Boolean isLike;

  @Override
    public Result likeBlog(Long id) 
        // 1.获取登录用户
        Long userId = UserHolder.getUser().getId();

        // 2.判断当前登录用户是否已经点赞
        String key = BLOG_LIKED_KEY + id;
        Boolean isMember = stringRedisTemplate.opsForSet().isMember(key, userId.toString());

        //3.如果未点赞，可以点赞
        if (BooleanUtil.isFalse(isMember)) 
            //3.1 数据库点赞数+1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            //3.2 保存用户到Redis的set集合
            if (isSuccess) 
                stringRedisTemplate.opsForSet().add(key, userId.toString());
            
         else 
            //4.如果已点赞，取消点赞
            //4.1 数据库点赞数-1
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            //4.2 把用户从Redis的set集合移除
            if (isSuccess) 
                stringRedisTemplate.opsForSet().remove(key, userId.toString());
            
        
        return Result.ok();
    

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4. 点赞排行榜

在探店笔记的详情页面，应该把给该笔记点赞的人显示出来，比如最早点赞的TOP5，形成点赞排行榜：

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我们接下来来对比一下这些集合的区别是什么？

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修改代码之前:BlogServiceImpl类实现

点赞逻辑 ：

   @Override
    public Result likeBlog(Long id) 
        // 1.获取登录用户
        Long userId = UserHolder.getUser().getId();
        // 2.判断当前登录用户是否已经点赞
        String key = BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if (score == null) 
            // 3.如果未点赞，可以点赞
            // 3.1.数据库点赞数 + 1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            // 3.2.保存用户到Redis的set集合  zadd key value score
            if (isSuccess) 
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            
         else 
            // 4.如果已点赞，取消点赞
            // 4.1.数据库点赞数 -1
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            // 4.2.把用户从Redis的set集合移除
            if (isSuccess) 
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            
        
        return Result.ok();
    


    private void isBlogLiked(Blog blog) 
        // 1.获取登录用户
        UserDTO user = UserHolder.getUser();
        if (user == null) 
            // 用户未登录，无需查询是否点赞
            return;
        
        Long userId = user.getId();
        // 2.判断当前登录用户是否已经点赞
        String key = "blog:liked:" + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    

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BlogController接口

@GetMapping("/likes/id")
public Result queryBlogLikes(@PathVariable("id") Long id) 

    return blogService.queryBlogLikes(id);

BlogService类实现

@Override
public Result queryBlogLikes(Long id) 
    String key = BLOG_LIKED_KEY + id;
    // 1.查询top5的点赞用户 zrange key 0 4
    Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
    if (top5 == null || top5.isEmpty()) 
        return Result.ok(Collections.emptyList());
    
    // 2.解析出其中的用户id
    List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
    String idStr = StrUtil.join(",", ids);
    // 3.根据用户id查询用户 WHERE id IN ( 5 , 1 ) ORDER BY FIELD(id, 5, 1)
    List<UserDTO> userDTOS = userService.query()
            .in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list()
            .stream()
            .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
            .collect(Collectors.toList());
    // 4.返回
    return Result.ok(userDTOS);

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完整的BlogServiceImpl代码：

@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService 

    @Resource
    private IUserService userService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Override
    public Result queryBlogById(Long id) 
        // 1.查询blog
        Blog blog = getById(id);
        if (blog == null) 
            return Result.fail("笔记不存在！");
        
        // 2.查询blog有关的用户
        queryBlogUser(blog);
        // 3. 查询是否点赞
        isBlogLiked(blog);
        return Result.ok(blog);
    

    @Override
    public Result queryHotBlog(Integer current) 
        // 根据用户查询
        Page<Blog> page = query().orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));

        // 获取当前页数据
        List<Blog> records = page.getRecords();

        // 查询用户
        records.forEach(blog ->
            this.queryBlogUser(blog); // 查用户
            this.isBlogLiked(blog);  // 查是否点赞
        );
        return Result.ok(records);
    

    @Override
    public Result likeBlog(Long id) 
        // 1.获取登录用户
        Long userId = UserHolder.getUser().getId();

        // 2.判断当前登录用户是否已经点赞
        String key = BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());

        //3.如果未点赞，可以点赞
        if (score == null) 
            //3.1 数据库点赞数+1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            //3.2 保存用户到Redis的Zset集合 zadd key value score
            if (isSuccess) 
                stringRedisTemplate.opsForZSet().add(key, userId.toString(),System.currentTimeMillis());
            
         else 
            //4.如果已点赞，取消点赞
            //4.1 数据库点赞数-1
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            //4.2 把用户从Redis的Zset集合移除
            if (isSuccess) 
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            
        
        return Result.ok();
    

    /**
     *  查询 TOP5 点赞用户列表
     * @param id
     * @return
     */
    @Override
    public Result queryBlogLikes(Long id) 
        String key = BLOG_LIKED_KEY + id;
        // 1.查询top5的点赞用户 zrange key 0 4
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (top5 == null || top5.isEmpty()) 
            return Result.ok(Collections.emptyList());
        
        System.out.println(top5);
        // 2.解析出其中的用户id
        List<Long> ids = top5.stream().
                map(Long::valueOf)
                .collect(Collectors.toList());
        String idStr = StrUtil.join(",", ids);
        // 3.根据用户id查询用户 WHERE id IN ( 5 , 1 ) ORDER BY FIELD(id, 5, 1)
        List<UserDTO> userDTOS = userService.query()
                .in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list() // 这里是因为 in 查询顺序不能保证，所以使用 ORDER BY FIELD()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        // 4.返回
        return Result.ok(userDTOS);
    

    private void queryBlogUser(Blog blog) 
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    

    private void isBlogLiked(Blog blog) 
        // 1.获取登录用户
        UserDTO user = UserHolder.getUser();
        if(user == null)
            // 用户未登录 无需查询
            return;
        
        Long userId = user.getId();
        // 2.判断当前登录用户是否已经点赞
        String key = BLOG_LIKED_KEY + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null );
    

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