问答平台（4），关注、取消关注

需求

1 2	`- 开发关注、取消关注功能。 - 统计用户的关注数、粉丝数。`

关键

1 2	`- 若A关注了B，则A是B的Follower(粉丝、关注者)，B是A的Followee(目标、被关注者)。 - 关注的目标可以是用户、帖子等，实现时将这些目标抽象为实体。`

工具类

RedisKeyUtil：增加内容

private static final String PREFIX_FOLLOWEE = "followee";
private static final String PREFIX_FOLLOWER = "follower";

// 某个用户关注的实体
// followee:userId:entityType -> zset(entityId, now)
public static String getFolloweeKey(int userId, int entityType) {
    return PREFIX_FOLLOWEE + SPLIT + userId + SPLIT + entityType;
}

// 某个实体拥有的粉丝
// follower:entityType:entityId -> zset(userId, now)
public static String getFollowerKey(int entityType, int entityId) {
    return PREFIX_FOLLOWER + SPLIT + entityType + SPLIT + entityId;
}

CommunityConstant：增加内容

/**
* 实体类型：用户
*/
int ENTITY_TYPE_USER = 3;

业务层

FollowService：新增

@Service
public class FollowService {
 
    @Autowired
    private RedisTemplate redisTemplate;

    @Autowired
    private UserService userService;

    // 关注
    public void follow(int userId, int entityType, int entityId) {
        redisTemplate.execute(new SessionCallback() {
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
                String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);

                // 启用事务
                operations.multi();

                operations.opsForZSet().add(followeeKey, entityId, System.currentTimeMillis());
                operations.opsForZSet().add(followerKey, userId, System.currentTimeMillis());

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

    // 取消关注
    public void unfollow(int userId, int entityType, int entityId) {
        redisTemplate.execute(new SessionCallback() {
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
                String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);

                // 启用事务
                operations.multi();

                operations.opsForZSet().remove(followeeKey, entityId);
                operations.opsForZSet().remove(followerKey, userId);

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

    // 查询关注实体的数量
    public long findFolloweeCount(int userId, int entityType) {
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().zCard(followeeKey);
    }

    // 查询实体的粉丝数量
    public long findFollowerCount(int entityType, int entityId) {
        String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);
        return redisTemplate.opsForZSet().zCard(followerKey);
    }

    // 查询当前用户是否已关注该实体
    public boolean hasFollowed(int userId, int entityType, int entityId) {
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().score(followeeKey, entityId) != null;
    }
}

表现层

FollowController：新增

@Controller
public class FollowController implements CommunityConstant {

    @Autowired
    private FollowService followService;

    @Autowired
    private HostHolder hostHolder;

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

        followService.follow(user.getId(), entityType, entityId);

        return CommunityUtil.getJSONString(0, "已关注!");
    }

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

        followService.unfollow(user.getId(), entityType, entityId);

        return CommunityUtil.getJSONString(0, "已取消关注!");
    }
}

UserController：修改

@Autowired
private FollowService followService;

// 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);

    // 关注数量
    long followeeCount = followService.findFolloweeCount(userId, ENTITY_TYPE_USER);
    model.addAttribute("followeeCount", followeeCount);
    // 粉丝数量
    long followerCount = followService.findFollowerCount(ENTITY_TYPE_USER, userId);
    model.addAttribute("followerCount", followerCount);
    // 是否已关注
    boolean hasFollowed = false;
    if (hostHolder.getUser() != null) {
        hasFollowed = followService.hasFollowed(hostHolder.getUser().getId(), ENTITY_TYPE_USER, userId);
    }
    model.addAttribute("hasFollowed", hasFollowed);

    return "/site/profile";
}

页面

profile.html

<!-- 内容 -->
<!-- 个人信息 -->
<input type="hidden" id="entityId" th:value="${user.id}">
<button type="button"
        th:class="|btn ${hasFollowed?'btn-secondary':'btn-info'} btn-sm float-right mr-5 follow-btn|"
        th:if="${loginUser!=null&&loginUser.id!=user.id}"
        th:text="${hasFollowed?'已关注':'关注TA'}">关注TA
</button>
<span>关注了 <a class="text-primary" th:href="@{|/followees/${user.id}|}"th:text="${followeeCount}">5</a> 人</span>
<span class="ml-4">关注者 <a class="text-primary" th:href="@{|/followers/${user.id}|}" th:text="${followerCount">123</a> 人</span>
<span class="ml-4">获得了 <i class="text-danger" th:text="${likeCount}">87</i> 个赞</span>

profile.js：修改

function follow() {
    var btn = this;
    if ($(btn).hasClass("btn-info")) {
        // 关注TA
        $.post(
            CONTEXT_PATH + "/follow",
            {"entityType": 3, "entityId": $(btn).prev().val()},
            function (data) {
                data = $.parseJSON(data);
                if (data.code == 0) {
                    window.location.reload();
                } else {
                    alert(data.msg);
                }
            }
        );
        // $(btn).text("已关注").removeClass("btn-info").addClass("btn-secondary");
    } else {
        // 取消关注
        $.post(
            CONTEXT_PATH + "/unfollow",
            {"entityType": 3, "entityId": $(btn).prev().val()},
            function (data) {
                data = $.parseJSON(data);
                if (data.code == 0) {
                    window.location.reload();
                } else {
                    alert(data.msg);
                }
            }
        );
        // $(btn).text("关注TA").removeClass("btn-secondary").addClass("btn-info");
    }
}

#问答平台

问答平台（4），关注、取消关注

https://lcf163.github.io/2020/05/26/问答平台（4），关注、取消关注/

作者

乘风的小站

发布于

2020年5月26日

许可协议

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