RabbitMQ系列教程（六）RabbitMQ Exchange類型之headers Exchange

RabbitMQ 四種Exchange類型

• RabbitMQ Exchange類型之Direct Exchange
• RabbitMQ Exchange類型之Topic Exchange
• RabbitMQ Exchange類型之fanout Exchange
• RabbitMQ Exchange類型之headers Exchange

headers Exchange介紹

headers Exchange與Direct、topic、fanout不同，它時通過匹配AMQP消息的header而非路由鍵。
headers Exchange與Direct Exchange類似，性能方面比後者查很多，所以在實際項目中用的很少，通過一張圖來直觀感受一下其工作流程

Java代碼實現

• 生產者

public static void main(String[] args) throws Exception{
        //1 創建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setUsername("guest");
        connectionFactory.setPassword("guest");
        //設置虛擬主機
        connectionFactory.setVirtualHost("/");
        //創建Connection
        Connection connection = connectionFactory.newConnection();
        //創建Channel
        Channel channel = connection.createChannel();
        //交換機名稱
        String exchangeName = "test_headers_exchange";

        //消息頭
        Map<String,Object> headers=new HashMap<>();
        headers.put("format","JSON");
        headers.put("type","pdf");
        //添加到headers
        AMQP.BasicProperties basicProperties = new AMQP.BasicProperties.Builder()
                .headers(headers)
                .build();

        // routingKey
        //發送5條消息
        for (int i=1;i<=5;i++) {
            String msg = "RabbitMQ headers Exchange  TEST"+i;
            channel.basicPublish(exchangeName, "", basicProperties , msg.getBytes());
        }
        channel.close();
        connection.close();
    }

• 消費者

在聲明消息隊列時，需要指定header參數，其中x-match爲特殊的headers，爲all時則表示要匹配所有的header，如果爲any則表示只要匹配其中的一個header即可

 Map<String,Object> arguments=new HashMap<>();
        arguments.put("x-match","all");
        //arguments.put("x-match","any");
        //聲明一個隊列
        channel.queueDeclare(queueName, false, false, false, arguments);

public static void main(String[] args) throws Exception{

        ConnectionFactory connectionFactory = new ConnectionFactory() ;

        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        connectionFactory.setUsername("guest");
        connectionFactory.setPassword("guest");
        connectionFactory.setAutomaticRecoveryEnabled(true);
        connectionFactory.setNetworkRecoveryInterval(3000);
        Connection connection = connectionFactory.newConnection();

        Channel channel = connection.createChannel();
        //交換機名稱
        String exchangeName = "test_headers_exchange";
        //交換機類型
        String exchangeType = "headers";
        //消息隊列名稱
        String queueName = "test_fanout_queue";
        //fanout模式不以routingKey爲匹配規則，可以爲空
        String routingKey = " ";

        //聲明交換機
        channel.exchangeDeclare(exchangeName, exchangeType, true, false, false, null);

        //隊列的參數
        //x-match爲特殊的headers，爲all時則表示要匹配所有的header，如果爲any則表示只要匹配其中的一個header即可
        Map<String,Object> arguments=new HashMap<>();
        arguments.put("x-match","all");
        //arguments.put("x-match","any");
        //聲明一個隊列
        channel.queueDeclare(queueName, false, false, false, arguments);
        //建立Exchange 和Queue綁定關係
        channel.queueBind(queueName, exchangeName, routingKey);


        //參數說明：隊列名稱、是否自動ACK、DefaultConsumer(消費者)
            channel.basicConsume(queueName, true,new DefaultConsumer(channel){
                @Override
                public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
                                           byte[] body) throws IOException {

                    System.out.println("收到消息："+new String(body));
                }
            });
    }

依次啓動消費者和生產者 ，在消費者控制檯可以看到接收到消息的輸出