redis用list做消息隊列的實現示例

leftPush消息入隊,rightPop對應,消息出隊。

rightPop(RedisConstant.MQ_LIST, 0L, TimeUnit.SECONDS)阻塞出隊,0表示永久阻塞

生產消息服務

@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對應,左邊入隊,右邊出隊
        listOperations.leftPush(RedisConstant.MQ_LIST, s);

        //因為出隊是阻塞讀取的,所以上一步入隊後,數據立刻就被驅走瞭,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;

    }
}

測試

@RestController
@RequestMapping("redisList")
public class RedisListController {

    @Autowired
    private RedisService redisService;

    @GetMapping("publish")
    public Object publish() {
        return redisService.publish();
    }
}

消費消息服務,定時任務

@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時間,表示阻塞永久
        //待機一小時後,再次發消息,消費不瞭瞭,阻塞有問題啊。還得輪尋啊
        //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("任務開始, " + lockKey + ", " + new Date());

            return pjp.proceed();

        } finally {
            lock.unlock();
            System.out.println("任務結束, " + lockKey + ", " + new Date());
        }
    }
}

測試

http://localhost:9040/redisList/publish

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

下面一直阻塞,任務開始瞭,不收到消息,永遠不會結束。
阻塞有問題,改用輪詢瞭。

先啟動發送消息服務,發送消息。後啟動消費消息服務,可以消費消息。這一點,比發佈訂閱要穩定。

關聯項目https://github.com/mingwulipo/cloud-demo.git

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