RabbitMQ - 延迟队列

rabbitmq的延迟队列，咱们能够经过死信交换器来实现。
生产者发送消息，定义2秒后消息过时，消息就会进入死信交换器，最后到死信队列。

// 定义队列的名称
public final static String QUEUE_NAME = "queue.scheduler";
// 定义交换器的名称
public final static String EXCHANGE_NAME = "exchange.scheduler";
// 定义路由的名称
public final static String ROUTE_NAME = "route.scheduler";
// 定义死信队列的名称
public final static String DLX_QUEUE_NAME = "scheduler.queue.name";
// 定义死信交换器的名称
public final static String DLX_EXCHANGE_NAME = "scheduler.exchange.name";

public static void main(String[] args) throws IOException, TimeoutException {
    // 声明一个链接工厂
    ConnectionFactory factory = new ConnectionFactory();
    // 建立一个与rabbitmq服务器的链接
    // 建立一个Channel
    try (Connection connection = factory.newConnection();
         Channel channel = connection.createChannel()) {
        // 定义交换器
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.DIRECT, false, false, null);
        Map<String, Object> arguments = new HashMap<String, Object>();
        arguments.put("x-dead-letter-exchange", DLX_EXCHANGE_NAME);
        arguments.put("x-message-ttl", 2000);
        // 定义队列
        channel.queueDeclare(QUEUE_NAME, false, false, false, arguments);
        // 绑定队列
        channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, ROUTE_NAME);
        // 定义死信交换器
        channel.exchangeDeclare(DLX_EXCHANGE_NAME, BuiltinExchangeType.DIRECT, false, false, null);
        // 定义死信队列
        channel.queueDeclare(DLX_QUEUE_NAME, false, false, false, null);
        // 绑定死信队列
        channel.queueBind(DLX_QUEUE_NAME, DLX_EXCHANGE_NAME, ROUTE_NAME);
        // 发送消息
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        channel.basicPublish(EXCHANGE_NAME, ROUTE_NAME, true, null, df.format(new Date()).getBytes());
    }
}

消费者，从私信队列获取消息，能够获得延迟后的消息。

public static void main(String[] args) throws IOException, TimeoutException {
    // 声明一个链接工厂
    ConnectionFactory factory = new ConnectionFactory();
    // 建立一个与rabbitmq服务器的链接
    Connection connection = factory.newConnection();
    // 建立一个Channel
    Channel channel = connection.createChannel();
    System.out.println("Waiting for messages.");
    // 异步回调处理
    DeliverCallback deliverCallback = (consumerTag, delivery) -> {
        String message = new String(delivery.getBody(), "UTF-8");
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println(df.format(new Date()) + " Received '" + message + "'");
    };
    // 接收消息
    channel.basicConsume(ProducerScheduler.DLX_QUEUE_NAME, true, deliverCallback, consumerTag -> {
    });
}

运行结果以下，达到了延迟队列的效果。除此以外，还能够用启用延迟插件。