社区网站项目4.5 关注列表、粉丝列表

  业务层

（1）查询某个用户关注的人，支持分页。

（2）查询某个用户的粉丝，支持分页。

  业务层

（1）处理“查询关注的人”、“查询粉丝”请求。

（2）编写“查询关注的人”、“查询粉丝”模板。

  在FollowService类里，添加

//查询某用户关注的人
    public List<Map<String, Object>> findFollowees(int userId, int offset, int limit){
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId,ENTITY_TYPE_USER);
        Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followeeKey,offset,offset+limit-1);

        if(targetIds==null){
            return null;
        }

        List<Map<String, Object>> list = new ArrayList<>();
        for (Integer targetId:targetIds){
            Map<String, Object> map = new HashMap<>();
            User user = userService.findUserById(targetId);
            map.put("user",user);
            Double score = redisTemplate.opsForZSet().score(followeeKey,targetId);
            map.put("followTime",new Date(score.longValue()));
            list.add(map);
        }

        return list;
    }

    //查询某用户的粉丝
    public List<Map<String, Object>> findFollowers(int userId,int offset,int limit){
        String followerKey = RedisKeyUtil.getFollowerKey(ENTITY_TYPE_USER,userId);
        //JDK中Set是无序的，但redis做了些内置处理所以返回的Set是有序的
        Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followerKey,offset,offset+limit-1); //虽然返回的是Set类型，但其实redis的内置方法opsForZSet().reverseRange()排出来的是有序的集合

        if(targetIds==null){
            return null;
        }

        List<Map<String, Object>> list = new ArrayList<>();
        for (Integer targetId:targetIds){
            Map<String, Object> map = new HashMap<>();
            User user = userService.findUserById(targetId);
            map.put("user",user);
            Double score = redisTemplate.opsForZSet().score(followerKey,targetId);
            map.put("followTime",new Date(score.longValue()));
            list.add(map);
        }

        return list;
    }
           

  在FollowController类里添加

@RequestMapping(path = "/followees/{userId}",method = RequestMethod.GET)
    public String getFollowees(@PathVariable("userId") int userId, Page page, Model model){
        User user = userService.findUserById(userId);
        if(user==null){
            throw new RuntimeException("该用户不存在！");
        }
        model.addAttribute("user",user);

        page.setLimit(5);
        page.setPath("/followees/"+userId);
        page.setRows((int)followService.findFolloweeCount(userId,ENTITY_TYPE_USER));

        List<Map<String,Object>> userList = followService.findFollowees(userId,page.getOffset(),page.getLimit());
        if(userList!=null){
            for(Map<String,Object> map: userList){
                User u = (User) map.get("user");
                map.put("hasFollowed",hasFollowed(u.getId()));
            }
        }
        model.addAttribute("users",userList);

        return "/site/followee";
    }

    @RequestMapping(path = "/followers/{userId}",method = RequestMethod.GET)
    public String getFollowers(@PathVariable("userId") int userId, Page page, Model model){
        User user = userService.findUserById(userId);
        if(user==null){
            throw new RuntimeException("该用户不存在！");
        }
        model.addAttribute("user",user);

        page.setLimit(5);
        page.setPath("/followers/"+userId);
        page.setRows((int)followService.findFollowerCount(ENTITY_TYPE_USER,userId));

        List<Map<String,Object>> userList = followService.findFollowers(userId,page.getOffset(),page.getLimit());
        if(userList!=null){
            for(Map<String,Object> map: userList){
                User u = (User) map.get("user");
                map.put("hasFollowed",hasFollowed(u.getId()));
            }
        }
        model.addAttribute("users",userList);

        return "/site/follower";
    }

    private boolean hasFollowed(int userId){
        if(hostHolder.getUser()==null){
            return false;
        }

        return followService.hasFollowed(hostHolder.getUser().getId(),ENTITY_TYPE_USER,userId);
    }
           

  在profile.html里“关注了 人”“关注者”的链接改一下。在followee.html和follower.html里修改选项和关注列表相关内容。