RabbitMQ中Confirm確認與Return返回消息詳解（八）

理解Confirm消息確認機制：

　　消息的確認，是指生產者投遞消息后，如果Broker收到消息，則會給我們生產這一個應答。

　　生產者進行接收應答，用來確定這條消息是否正常的發送到Broker，這種方式也是消息的可靠性投遞的核心保障。

 　　

　　如何實現Confirm確認消息？

　　　　第一步：在channel上開啟確認模式：channel.confirmSelect()

　　　　第二步：在channel上添加監聽：addConfirmListener，監聽成功和失敗的返回結果，

　　　　　　　　根據具體的結果對消息進行重新發送、或者記錄日志等后續處理。

     //生產端代碼   
     //1 創建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        //2 獲取C    onnection
        Connection connection = connectionFactory.newConnection();
        
        //3 通過Connection創建一個新的Channel
        Channel channel = connection.createChannel();
        
        
        //4 指定我們的消息投遞模式: 消息的確認模式 
        channel.confirmSelect();
        
        String exchangeName = "test_confirm_exchange";
        String routingKey = "confirm.save";
        
        //5 發送一條消息
        String msg = "Hello RabbitMQ Send confirm message!";
        channel.basicPublish(exchangeName, routingKey, null, msg.getBytes());
        
        //6 添加一個確認監聽
        channel.addConfirmListener(new ConfirmListener() {
            @Override
            public void handleNack(long deliveryTag, boolean multiple) throws IOException {
                System.err.println("-------no ack!-----------");
            }
            
            @Override
            public void handleAck(long deliveryTag, boolean multiple) throws IOException {
                System.err.println("-------ack!-----------");
            }
        });    

 

    //消費端代碼
    //1 創建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        //2 獲取C    onnection
        Connection connection = connectionFactory.newConnection();
        
        //3 通過Connection創建一個新的Channel
        Channel channel = connection.createChannel();
        
        String exchangeName = "test_confirm_exchange";
        String routingKey = "confirm.#";
        String queueName = "test_confirm_queue";
        
        //4 聲明交換機和隊列 然后進行綁定設置, 最后制定路由Key
        channel.exchangeDeclare(exchangeName, "topic", true);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);
        
        //5 創建消費者 
        QueueingConsumer queueingConsumer = new QueueingConsumer(channel);
        channel.basicConsume(queueName, true, queueingConsumer);
        
        while(true){
            Delivery delivery = queueingConsumer.nextDelivery();
            String msg = new String(delivery.getBody());
            
            System.err.println("消費端: " + msg);
        }

 Return消息機制

　　Return Listener用於處理一些不可路由的消息。

　　我們的消息生產者，通過指定一個Exchange和Routingkey，把消息送到某一個隊列中，

　　然后我們的消費者監聽隊列，進行消息處理操作。

　　但是在某些情況下，如果我們在發送消息的時候，當前的exchange不存在或者指定的路由key路由不到，

　　這個時候我們需要監聽這種不可達的消息，就要使用return listener。

　　

　　在基礎API中有一個關鍵的配置項：

　　　　Mandatory：如果為true，則監聽會接收到路由不可達的消息，然后進行后續處理，

　　　　　　　　　　如果為false，那么broker端自動刪除該消息。（默認false）

　　　　　　　　　　

                //生產端代碼   
             ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();
        
        String exchange = "test_return_exchange";
        String routingKey = "return.save";
        String routingKeyError = "abc.save";
        
        String msg = "Hello RabbitMQ Return Message";
        
        
        channel.addReturnListener(new ReturnListener() {
            @Override
            public void handleReturn(int replyCode, String replyText, String exchange,
                    String routingKey, AMQP.BasicProperties properties, byte[] body) throws IOException {
                
                System.err.println("---------handle  return----------");
                System.err.println("replyCode: " + replyCode);
                System.err.println("replyText: " + replyText);
                System.err.println("exchange: " + exchange);
                System.err.println("routingKey: " + routingKey);
                System.err.println("properties: " + properties);
                System.err.println("body: " + new String(body));
            }
        });
        
        
        channel.basicPublish(exchange, routingKeyError, true, null, msg.getBytes());
            

         //消費端代碼
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();
        
        String exchangeName = "test_return_exchange";
        String routingKey = "return.#";
        String queueName = "test_return_queue";
        
        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);
        
        QueueingConsumer queueingConsumer = new QueueingConsumer(channel);
        
        channel.basicConsume(queueName, true, queueingConsumer);
        
        while(true){
            
            Delivery delivery = queueingConsumer.nextDelivery();
            String msg = new String(delivery.getBody());
            System.err.println("消費者: " + msg);
        }

　　運行結果：