java mq优点和缺点 java中mq的使用

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梦里忧郁 2023-07-20 12:00:12

文章标签 java mq优点和缺点 rabbitmq java Consumer spring-amqp 文章分类 Java 后端开发

rabbitmq作为消息队列，在实际应用中很常见，生产者将消息发送到某个队列，消费者消费这个队列。

消息在队列中，消费者要消费，需要监听队列，简单的来说，就是注册一个方法到消息通道，这个方法就会在有消息的时候执行。

下面通过java来操作rabbitmq，给出代码示例。

这里介绍三种消费者示例方法

1、最简单的注册。

直接通过channel.basicConsume()设置callback。

2、模拟一个队列消费者，启动线程。

自定义一个消费者，并且将消费者当做一个线程启动。

以上只需要amqp-client依赖

<dependency>
    	<groupId>com.rabbitmq</groupId>
    	<artifactId>amqp-client</artifactId>
    	<version>5.4.3</version>
</dependency>

3、利用springboot对amqp的支持，通过自定义MessageListener然后，绑定到Container。

这是最常见的做法，自定义监听器，设置消息处理方法。将监听器注入消息监听容器，最后启动容器。

这里需要加入spring-boot-starter-amqp依赖。

<dependency>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-amqp</artifactId>
    	<version>2.1.4.RELEASE</version>
</dependency>

下面给出以上介绍的三种消费者示例代码：

1、这个做法比较原始，也是最容易看懂的。

package com.xxx.huali.hualitest.amqp;
import java.io.IOException;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Consumer;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;
import com.rabbitmq.client.AMQP.BasicProperties;

public class SimpleConsumer {
	
	private static final String host = "192.168.226.100";
	private static final String username = "huali";
	private static final String password = "huali";
	private static final String queue_name1 = "activate";
	private static final String exchange_name = "core.down.topic";
	public static void main(String[] args) {
		Connection conn = null;
		Channel channel = null;
		try {
			ConnectionFactory factory = new ConnectionFactory();
			factory.setHost(host);
			factory.setUsername(username);
			factory.setPassword(password);
			factory.setVirtualHost("/mec");
			
			//connection
			conn = factory.newConnection();
			//channel
			channel = conn.createChannel();
			//queue
			channel.queueDeclare(queue_name1, true, false, false, null);
			//exchange
			channel.exchangeDeclare(exchange_name, "topic",true);
			channel.queueBind(queue_name1, exchange_name, "TOPIC.*.*.*.*");
			Consumer callback = new DefaultConsumer(channel) {
				@Override
				public void handleDelivery(String consumerTag, Envelope envelope, 
BasicProperties properties,byte[] body) throws IOException {
					System.out.println("received message -> "+new String(body));
				}
			};
			channel.basicConsume(queue_name1, true, callback);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

2、这种方式在第一种的基础上，增加了线程，启动线程，设置监听，有点像第三种方式。

package com.xxx.huali.hualitest.amqp;
import java.io.IOException;
import com.rabbitmq.client.AMQP.BasicProperties;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Consumer;
import com.rabbitmq.client.Envelope;
import com.rabbitmq.client.ShutdownSignalException;
public class QueueConsumer implements Consumer,Runnable{
	private static final String host = "192.168.226.100";
	private static final String username = "huali";
	private static final String password = "huali";
	private static final String queue_name1 = "activate";
	private static final String exchange_name = "core.down.topic";
	Connection conn = null;
	Channel channel = null;
	public QueueConsumer(){
		
		try {
			ConnectionFactory factory = new ConnectionFactory();
			factory.setHost(host);
			factory.setUsername(username);
			factory.setPassword(password);
			factory.setVirtualHost("/mec");
			
			//connection
			conn = factory.newConnection();
			//channel
			channel = conn.createChannel();
			
			//queue
			channel.queueDeclare(queue_name1, true, false, false, null);
			//exchange
			channel.exchangeDeclare(exchange_name, "topic",true);
			channel.queueBind(queue_name1, exchange_name, "TOPIC.*.*.*.*");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public void close() throws IOException{
		try {
			channel.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		this.conn.close();
	}

	@Override
	public void run() {
		try {
			channel.basicConsume(queue_name1, true, this);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	@Override
	public void handleConsumeOk(String consumerTag) {}

	@Override
	public void handleCancelOk(String consumerTag) {}

	@Override
	public void handleCancel(String consumerTag) throws IOException {}

	@Override
	public void handleDelivery(String consumerTag, Envelope env, BasicProperties props, 
byte[] body) throws IOException {
		
		System.out.println("client received msg -> "+new String(body));
	}

	@Override
	public void handleShutdownSignal(String consumerTag, ShutdownSignalException sig) {}

	@Override
	public void handleRecoverOk(String consumerTag) {}
	
}

启动主函数：

package com.xxx.huali.hualitest.amqp;

public class ConsumerMain {
	public static void main(String[] args) {
		QueueConsumer consumer = new QueueConsumer();
		Thread thread = new Thread(consumer);
		thread.start();
	}
}

3、第三种方式需要借助spring-amqp的支持。它在实际开发中最常见，在springboot中，ConnectionFactory都直接配置了，连代码都不需要码了，我们只需要配置一个消息监听器就可以了。

package com.xxx.springbootamqp.test;

import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageListener;

public class MyMessageListener implements MessageListener{

	@Override
	public void onMessage(Message message) {

		System.out.println("received message -> "+new String(message.getBody()));
	}

}

启动主函数：

package com.xxx.springbootamqp.test;
import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
public class ConsumerMain {
	private static final String host = "192.168.226.100";
	private static final String username = "huali";
	private static final String password = "huali";
	private static final String queue_name1 = "activate";
	public static void main(String[] args) {
		try {
			CachingConnectionFactory factory = new CachingConnectionFactory();
			factory.setHost(host);
			factory.setUsername(username);
			factory.setPassword(password);
			factory.setVirtualHost("/mec");
			
			SimpleMessageListenerContainer container = new 
SimpleMessageListenerContainer(factory);
			container.setMessageListener(new MyMessageListener());
			container.setQueueNames(queue_name1);
			container.start();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

这段代码严格来说，并不完整，没有声明队列，交换机，以及队列和交换机的绑定关系，因为消费者一旦绑定了交换机和队列的关系，后面就不需要重复设置了，这个关系就在rabbitmq中形成了，只要不手动删除，他自己不会改变。因为这是第三个示例，前面的两个示例已经对队列和交换机做了设置和绑定。

这里需要启动容器，类似第二种的启动线程，其实这里也是利用了线程池，算是第二种方式的增强版。而且消费者封装成了BlockingQueueConsumer，更加符合队列消费者的语义。

有一点需要说明的是，这里采用的队列是和交换机进行绑定的，而交换机的类型是主题交换机，消息生产者只需要将消息发送到交换机对应的路由key上即可。也就是routingKey。

channel.basicPublish(exchange_name, "TOPIC.4.128.1.a1OHmhQSyrxMEC_1", null, 
message.getBytes());

代码里面的 TOPIC.4.128.1.a1OHmhQSyrxMEC_1就是routingKey。

消费者自己绑定主题交换机和队列，一个消费者，可以申请一个队列，两个消费者申请两个队列，这样，消息就路由到了多个消费者那里，而且互不干扰。

//queue
channel.queueDeclare(queue_name1, true, false, false, null);
//exchange
channel.exchangeDeclare(exchange_name, "topic",true);
channel.queueBind(queue_name1, exchange_name, "TOPIC.*.*.*.*");

最后附上一个简单的生产者代码示例：

package com.xxx.huali.hualitest.amqp;

import java.io.IOException;
import java.util.Date;
import java.util.concurrent.TimeoutException;

import com.alibaba.fastjson.JSONObject;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class Publisher {
	private static final String host = "192.168.226.100";
	private static final String username = "huali";
	private static final String password = "huali";
	
	private static final String exchange_name = "core.down.topic";
	
	public static void main(String[] args) {
		Connection conn = null;
		Channel channel = null;
		try {
			ConnectionFactory factory = new ConnectionFactory();
			factory.setHost(host);
			factory.setUsername(username);
			factory.setPassword(password);
			factory.setVirtualHost("/mec");
			
			//connection
			conn = factory.newConnection();
			//channel
			channel = conn.createChannel();
			//exchange
			channel.exchangeDeclare(exchange_name, "topic",true);
			JSONObject object = new JSONObject();
			String device_id = "a1OHmhQSyrxMEC_1";
			object.put("device_id", device_id);
			object.put("opt_type", 128);
			JSONObject data = new JSONObject();
			data.put("auzcode_devname", device_id);
			data.put("regist_result", 1);
			long time_stamp = new Date().getTime();
			object.put("data", data);
			object.put("time_stamp", time_stamp);
			String message = object.toJSONString();
			//for(int i=0;i<5;i++) {
			//	System.out.println("i="+i);
				channel.basicPublish(exchange_name, "TOPIC.4.128.1.a1OHmhQSyrxMEC_1", null, message.getBytes());
			//}
			System.out.println("done");
			
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			try {
				channel.close();
				conn.close();
			} catch (IOException e) {
				e.printStackTrace();
			} catch (TimeoutException e) {
				e.printStackTrace();
			}
		}
	}
}

生产者代码很简单，最关键的一句就是channel.basicPublish()那句发送消息代码。它只关心发送到哪个主题，哪个路由上，不关心队列。

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