@Configuration //編寫redis的配置類
public class RedisConfig {
    @Bean //參數聲明了連接工廠
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(factory);
        // 設置key的序列化方式
        template.setKeySerializer(RedisSerializer.string());
        // 設置value的序列化方式
        template.setValueSerializer(RedisSerializer.json());
        // 設置hash的key的序列化方式
        template.setHashKeySerializer(RedisSerializer.string());
        // 設置hash的value的序列化方式
        template.setHashValueSerializer(RedisSerializer.json());
           //讓設置生效
        template.afterPropertiesSet();
        return template;
    }
}
public class RedisKeyUtil {
    private static final String SPLIT = ":";
    private static final String PREFIX_ENTITY_LIKE = "like:entity";
    // 某個實體的贊
    // like:entity:entityType:entityId -> set(userId)
    public static String getEntityLikeKey(int entityType, int entityId) {
        return PREFIX_ENTITY_LIKE + SPLIT + entityType + SPLIT + entityId;
    }
    }

@Service
public class LikeService {
    @Autowired
    private RedisTemplate redisTemplate;
    // 點贊  誰點的贊 點贊的實體 實體的id 實體的用戶
    public void like(int userId, int entityType, int entityId, ) {
        redisTemplate.execute(new SessionCallback() {
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
                String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
                boolean isMember = operations.opsForSet().isMember(entityLikeKey, userId);
                   //是否已經點過贊
                if (isMember) { //移除userid
                    operations.opsForSet().remove(entityLikeKey, userId);
                    operations.opsForValue().decrement(userLikeKey);
                } else { //添加userid
                    operations.opsForSet().add(entityLikeKey, userId);
                    operations.opsForValue().increment(userLikeKey);
                }
            }
        });
    }
    // 查詢某實體點贊的數量
    public long findEntityLikeCount(int entityType, int entityId) {
        String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
        return redisTemplate.opsForSet().size(entityLikeKey);
    }
    // 查詢某人對某實體的點贊狀態(tài)
    public int findEntityLikeStatus(int userId, int entityType, int entityId) {
        String entityLikeKey = RedisKeyUtil.getEntityLikeKey(entityType, entityId);
        //1表示點贊 0表示沒有
        return redisTemplate.opsForSet().isMember(entityLikeKey, userId) ? 1 : 0;
    }

@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();
        // 點贊
        likeService.like(user.getId(), entityType, entityId, entityUserId);
        // 數量
        long likeCount = likeService.findEntityLikeCount(entityType, entityId);
        // 狀態(tài)
        int likeStatus = likeService.findEntityLikeStatus(user.getId(), entityType, entityId);
        // 返回的結果
        Map<String, Object> map = new HashMap<>();
        map.put("likeCount", likeCount);
        map.put("likeStatus", likeStatus);
        return CommunityUtil.getJSONString(0, null, map);
    }
}
//回調函數
function like(btn, entityType, entityId, entityUserId) {
    $.post(
        CONTEXT_PATH + "/like",
        {"entityType":entityType,"entityId":entityId,"entityUserId":entityUserId},
        function(data) {
            data = $.parseJSON(data);
            if(data.code == 0) {
                $(btn).children("i").text(data.likeCount);
                $(btn).children("b").text(data.likeStatus==1?'已贊':"贊");
            } else {
                alert(data.msg);
            }
        }
    );
}