redis用list做消息队列

落日映苍穹つ 2023-06-15 11:11 128阅读 0赞

leftPush消息入队，rightPop对应，消息出队。  
rightPop(RedisConstant.MQ\_LIST, 0L, TimeUnit.SECONDS)阻塞出队，0表示永久阻塞

## 生产消息服务 ##

@Service
    public class RedisService { 
        @Autowired
        private RedisTemplate<String, String> redisTemplate;
    
    
        public Object publish() { 
            OrderDTO dto = new OrderDTO();
            dto.setId(1);
            dto.setCreateTime(new Date());
            dto.setMoney("12.34");
            dto.setOrderNo("orderNo1");
            String s = JSON.toJSONString(dto);
    
            ListOperations<String, String> listOperations = redisTemplate.opsForList();
            //leftPush和rightPop对应，左边入队，右边出队
            listOperations.leftPush(RedisConstant.MQ_LIST, s);
    
            //因为出队是阻塞读取的，所以上一步入队后，数据立刻就被驱走了，下一步size=0
            Long size = listOperations.size(RedisConstant.MQ_LIST);
            List<String> list = new ArrayList<>();
            if (size != null && size > 0) { 
                 list = listOperations.range(RedisConstant.MQ_LIST, 0, size - 1);
            }
            return list;
    
        }
    }

测试

@RestController
    @RequestMapping("redisList")
    public class RedisListController { 
    
        @Autowired
        private RedisService redisService;
    
        @GetMapping("publish")
        public Object publish() { 
            return redisService.publish();
        }
    }

## 消费消息服务，定时任务 ##

@Component
    public class RedisConsumeTask { 
        @Autowired
        private RedisService redisService;
    
        @TaskLock(RedisConstant.CONSUME_REDIS_LIST)
        @Scheduled(cron = "0/10 * * * * ?")
        public void consumeMqList() { 
            redisService.consumeMqList();
        }
    }
    
    @Service
    @Slf4j
    public class RedisService { 
    
        @Autowired
        private RedisTemplate<String, String> redisTemplate;
    
        public void consumeMqList() { 
            ListOperations<String, String> listOperations = redisTemplate.opsForList();
            //0时间，表示阻塞永久
            //待机一小时后，再次发消息，消费不了了，阻塞有问题啊。还得轮寻啊
            //String s = listOperations.rightPop(RedisConstant.MQ_LIST, 0L, TimeUnit.SECONDS);
            String s = listOperations.rightPop(RedisConstant.MQ_LIST);
            if (s == null) { 
                return;
            }
    
            log.info("{} = {}", RedisConstant.MQ_LIST, s);
    
            OrderDTO dto = JSON.parseObject(s, OrderDTO.class);
            log.info("dto = {}", dto);
        }
    }

## 日志 ##

@Component
    @Aspect
    public class TaskLockAop { 
    
        @Autowired
        private RedisLockRegistry redisLockRegistry;
    
        @Around("execution(@TaskLock * * (..))")
        public Object taskAround(ProceedingJoinPoint pjp) throws Throwable { 
    
            TaskLock taskAnnotation = ((MethodSignature)pjp.getSignature()).getMethod().getAnnotation(TaskLock.class);
    
            String lockKey = taskAnnotation.value();
            Lock lock = redisLockRegistry.obtain(lockKey);
            try { 
                lock.tryLock(30L, TimeUnit.SECONDS);
                System.out.println("任务开始, " + lockKey + ", " + new Date());
    
                return pjp.proceed();
    
            } finally { 
                lock.unlock();
                System.out.println("任务结束, " + lockKey + ", " + new Date());
            }
        }
    
    
    }

## 测试 ##

http://localhost:9040/redisList/publish

\["\{“createTime”:1574394538430,“id”:1,“money”:“12.34”,“orderNo”:“orderNo1”\}"\]

![在这里插入图片描述][20191122115107899.png]

下面一直阻塞，任务开始了，不收到消息，永远不会结束。  
阻塞有问题，改用轮询了。

先启动发送消息服务，发送消息。后启动消费消息服务，可以消费消息。这一点，比发布订阅要稳定。

关联项目https://github.com/mingwulipo/cloud-demo.git

[20191122115107899.png]: https://img-blog.csdnimg.cn/20191122115107899.png