我收到的赞（二十）

重构点赞功能
- 以用户为key，记录点赞数量
- increment(key), decrement(key)
开发个人主页
- 以用户为key，查询点赞数量

一、补充RedisKeyUtil

生成用户id的key，存放给该用户点过赞的用户id

public class RedisKeyUtil {
    // ...
    // 用户前缀
    private static final String PREFIX_USER_LIKE = "like:user";
    // ...
    // 某个用户的赞
    // like:user:userId -> int
    public static String getUserLikeKey(int userId) {
        return PREFIX_USER_LIKE + SPLIT + userId;
    }
}

二、重构业务层点赞方法

重构like，同时给实体和用户点赞

@Service
public class LikeService {

    @Autowired
    private RedisTemplate redisTemplate;

    // 点赞
    // 同时给实体和作者点赞
    public void like(int userId, int entityType, int entityId, int entityUserId) {
        redisTemplate.execute(new SessionCallback() {
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
                // 实体key
                String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
                // 用户key
                String userLikeKey = RedisKeyUtil.getUserLikeKey(entityUserId);
                // 在事务开启前查询
                boolean isMember = operations.opsForSet().isMember(entityLikeKey, userId);
                // 开启事务
                operations.multi();

                if (isMember) {
                    // 取消点赞
                    operations.opsForSet().remove(entityLikeKey, userId);
                    operations.opsForValue().decrement(userLikeKey);
                } else {
                    // 点赞
                    operations.opsForSet().add(entityLikeKey, userId);
                    operations.opsForValue().increment(userLikeKey);
                }

                return operations.exec();
            }
        });
    }

    // 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;
    }

    // 查询某个用户获得的赞
    public int findUserLikeCount(int userId) {
        String userLikeKey = RedisKeyUtil.getUserLikeKey(userId);
        Integer count = (Integer) redisTemplate.opsForValue().get(userLikeKey);
        return count == null ? 0 : count.intValue();
    }

}

三、重构表现层

@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, int entityUserId) {
        User user = hostHolder.getUser();

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

        // 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);
    }
}

处理页面（略）

四、访问个人主页

能够查看获得了多少个赞
UserConrtoller.java

    // 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);
        return "/site/profile";
    }