RabbitMQ实战-死信队列
场景说明
场景: 当队列的消息未正常被消费时,如何解决?
- 消息被拒绝并且不再重新投递
- 消息超过有效期
- 队列超载
方案: 未被消费的消息,可通过"死信队列"重新被消费
死信队列含义,发生以上情况时,该队列上的消息,可通过配置转发到死信队列,被重新消费
模拟实现:
- 1个生产者,2个交换机和队列(普通和死信),1个消费者(死信消费者)
- 通过消息超时,模拟未正常消费场景
- 启动死信队列消费者,等待消息...
- 启动生产者,绑定死信队列并发送消息
- 消息超时后,由死信队列消费者消费
代码实现
简单的Util
package com.lyf.springboot.utils;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import java.io.IOException;
import java.util.concurrent.TimeoutException;
public class MqUtil {
private static Connection connection = null;
private static Channel channel = null;
/**
* 获取channel
* @return
*/
public static Channel getChannel(){
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("192.168.37.200");
factory.setUsername("lyf");
factory.setPassword("123456");
factory.setVirtualHost("/lyf");
try {
connection = factory.newConnection();
channel = connection.createChannel();
} catch (IOException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
}
return channel;
}
/**
* 关闭channel和connection
*/
public static void close(){
try {
if(channel != null){
channel.close();
}
if(connection != null){
connection.close();
}
} catch (IOException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
}
}
}
生产者
package com.lyf.springboot.mq;
import com.lyf.springboot.utils.MqUtil;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
public class Sender {
private static String QUEUE_NAME="hello";
private static String EXCHANGE_NAME="exchange";
private static String DL_EXCHANGE_NAME="dl_exchange";
public static void main(String []args) throws IOException {
Channel channel = MqUtil.getChannel();
// 普通队列
channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
Map<String, Object> arguments = new HashMap<>();
/*--------------↓↓↓最关键一步,设置队列的死信队列↓↓↓----------------*/
// x-dead-letter-exchange属性用于指定死信队列
arguments.put("x-dead-letter-exchange", DL_EXCHANGE_NAME);
channel.queueDeclare(QUEUE_NAME,false,false,false,arguments);
/*--------------↑↑↑最关键一步,设置队列的死信队列↑↑↑----------------*/
channel.queueBind(QUEUE_NAME,EXCHANGE_NAME,"info");
// 设置超时时间5000ms
AMQP.BasicProperties properties = new AMQP.BasicProperties().builder().expiration("5000").build();
String msg = "hello";
channel.basicPublish(EXCHANGE_NAME, "info", properties, msg.getBytes());
System.out.println("Se: " + msg);
MqUtil.close();
}
}
消费者
package com.lyf.springboot.mq;
import com.lyf.springboot.utils.MqUtil;
import com.rabbitmq.client.*;
import java.io.IOException;
public class Dl_Reciver {
private static String DL_EXCHANGE_NAME="dl_exchange";
private static String DL_QUEUE_NAME="dl_hello";
public static void main(String []args) throws IOException {
Channel channel = MqUtil.getChannel();
channel.exchangeDeclare(DL_EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
channel.queueDeclare(DL_QUEUE_NAME,false,false,false,null);
channel.queueBind(DL_QUEUE_NAME,DL_EXCHANGE_NAME,"#");
// 消费者
DefaultConsumer consumer = new DefaultConsumer(channel) {
@Override
public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
String msg = new String(body, "utf-8");
System.out.println("DL_Re: " + msg);
}
};
channel.basicConsume(DL_QUEUE_NAME,false,consumer);
}
}
启动顺序: 先启动消费者监听,后启动生产者.消息5s后被死信队列消费
参考:
