Redis实现方式未读消息计数的示例代码实用指南

// 添加未读数（默认新增1条待审核提醒）
appletRedisUtil.addUnreadCount(cityPartner.getId());

import jakarta.annotation.Resource;
import org.springblade.business.constant.RedisKeyConstant;
import org.springblade.business.pojo.entity.ProductApplyRecord;
import org.springblade.business.service.ProductApplyRecordService;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import java.util.Objects;
 
@Component // 注入Spring容器，全局可用
public class AppletRedisUtil {
 
    @Resource
    private RedisTemplate<String, Long> redisTemplate; // 操作Redis的核心组件
 
    // 1. 重载方法：默认给城市合伙人新增1条未读消息
    public void addUnreadCount(Long miniUserId) {
        addUnreadCount(miniUserId, 1L);
    }
 
    // 2. 核心方法：支持自定义新增未读条数，含数据准确性校验
    public void addUnreadCount(Long miniUserId, Long value) {
        // 2.1 工具类无法直接注入Service，通过Spring上下文获取
        ProductApplyRecordService productApplyRecordService = SpringContextUtil.getBean(ProductApplyRecordService.class);
        
        // 2.2 查该城市合伙人的总申请数（未读上限，避免未读数超过实际总数）
        Long totalCount = productApplyRecordService.lambdaQuery()
            .eq(ProductApplyRecord::getCityPartnerId, miniUserId)
            .count();
        
        // 2.3 查当前Redis中的未读数量（空值兜底返回0，避免空指针）
        Long currentUnread = getUnreadCount(miniUserId);
        
        // 2.4 修正未读数量：若累加后超总申请数，取总申请数（防止数据异常）
        value = (currentUnread + value) > totalCount ? totalCount : (currentUnread + value);
        
        // 2.5 更新Redis：用“常量前缀+用户ID”作为key，原子自增未读数量
        redisTemplate.opsForValue().increment(RedisKeyConstant.PRODUCT_APPLY_UNREAD_NUM + miniUserId, value);
    }
 
    // 3. 查询未读数量：空值兜底，确保返回非null
    public Long getUnreadCount(Long miniUserId) {
        String key = RedisKeyConstant.PRODUCT_APPLY_UNREAD_NUM + miniUserId;
        Long unread = redisTemplate.opsForValue().get(key);
        return Objects.isNull(unread) ? 0L : unread;
    }
 
    // 4. 重置未读数量：先置0再删key，确保状态彻底清空
    public void resetUnreadCount(Long miniUserId) {
        String key = RedisKeyConstant.PRODUCT_APPLY_UNREAD_NUM + miniUserId;
        redisTemplate.opsForValue().set(key, 0L);
        redisTemplate.delete(key);
    }
}