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想玩一玩RabbitMQ中的ShutdownListener和RecoveryListener，又不想写自己的重连接逻辑，所以使用了ConnectionFactory类的setAutomaticRecoveryEnabled方法让其自动恢复连接。代码如下：

package com.yqu.rabbitmq;import com.rabbitmq.client.*;import java.io.IOException;public class AutoRecoveryRecv {  private final static String QUEUE_NAME = "hello";  public static void main(String[] argv) throws Exception {    try {      ConnectionFactory factory = new ConnectionFactory();      factory.setHost(ConnectionFactoryConfiguration.HOST);      factory.setUsername(ConnectionFactoryConfiguration.USERNAME);      factory.setPassword(ConnectionFactoryConfiguration.PASSWORD);      factory.setAutomaticRecoveryEnabled(true);      factory.setNetworkRecoveryInterval(10000);      Connection connection = factory.newConnection();      connection.addShutdownListener(new ShutdownListener() {        @Override        public void shutdownCompleted(ShutdownSignalException cause)        {          String hardError = "";          String applInit = "";          if (cause.isHardError()) {            hardError = "connection";          } else {            hardError = "channel";          }          if (cause.isInitiatedByApplication()) {            applInit = "application";          } else {            applInit = "broker";          }          System.out.println("Connectivity to MQ has failed.  It was caused by "                  + applInit + " at the " + hardError                  + " level.  Reason received " + cause.getReason());        }      });      ((Recoverable)connection).addRecoveryListener(new RecoveryListener() {        @Override        public void handleRecovery(Recoverable recoverable) {          if( recoverable instanceof Connection ) {            System.out.println("Connection was recovered.");          } else if ( recoverable instanceof Channel ) {            int channelNumber = ((Channel) recoverable).getChannelNumber();            System.out.println( "Connection to channel #"                    + channelNumber + " was recovered." );          }        }      });      Channel channel = connection.createChannel();      channel.queueDeclare(QUEUE_NAME, false, false, false, null);      System.out.println(" [*] Waiting for messages. To exit press CTRL+C");      Consumer consumer = new DefaultConsumer(channel) {        @Override        public void handleDelivery(String consumerTag, Envelope envelope,                                   AMQP.BasicProperties properties, byte[] body)                throws IOException {          String message = new String(body, "UTF-8");          System.out.println(" [x] Received '" + message + "'");        }      };      channel.basicConsume(QUEUE_NAME, true, consumer);    }    catch(Throwable t) {      t.printStackTrace();    }  }}

重启了RabbitMQ所在的服务器，然后获得下列日志，显示连接已修复，然后才调用ShutdownListener显示连接关闭信息：

为什么会这样？下面就开始我的解密之旅！

首先看一下ShutdownNotifier接口的层次图，Connection下共有三个子孙类，尚不确定在我的测试里是哪一个？

看一下com.rabbitmq.client.ConnectionFactory类newConnection方法实现，豁然开朗！对于ConnectionFactory类，如果automaticRecoveryEnabled被设置则创建AutorecoveringConnection，否则创建AMQConnection。而RecoveryAwareAMQConnectionFactory才会创建RecoveryAwareAMQConnection。

AutorecoveringConnection类init方法会调用addAutomaticRecoveryListener方法，addAutomaticRecoveryListener方法会添加一个ShutdownListener类实例automaticRecoveryListener到列表shutdownListeners，而我创建的ShutdownListener类实例是列表shutdownListeners中的第二个元素。

参看下面堆栈信息，ShutdownNotifierComponent类的notifyListeners会遍历所有shutdownListeners列表所有监听器，第一个关闭监听器实例automaticRecoveryListener会进行连接修复并通知RecoveryListener，然后才到我的关闭监听器打印关闭信息。

at AutoRecoveryRecv$2.handleRecovery(AutoRecoveryRecv.at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.notifyRecoveryListeners(AutorecoveringConnection.at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.beginAutomaticRecovery(AutorecoveringConnection.- locked <0x30d> (a com.rabbitmq.client.impl.recovery.AutorecoveringConnection)at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.access$000(AutorecoveringConnection.at com.rabbitmq.client.impl.recovery.AutorecoveringConnection$1.shutdownCompleted(AutorecoveringConnection.at com.rabbitmq.client.impl.ShutdownNotifierComponent.notifyListeners(ShutdownNotifierComponent.at com.rabbitmq.client.impl.AMQConnection$MainLoop.run(AMQConnection.at

项目在https://github.com/rabbitmq/rabbitmq-java-client/pull/136修正了这个错误，先通知所有ShutdownListener再尝试自动修复连接。但是在我所用的amqp-client-3.6.5.jar还没有包含这一修改。

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