RockerMQ消息发送模式

简介

RocketMQ有三种发送模式，分别是同步发送、异步发送、单向发送，不同的模式适用于不同的业务场景

maven依赖

<dependency>
    <groupId>org.apache.rocketmq</groupId>
    <artifactId>rocketmq-client</artifactId>
    <version>4.6.1</version>
</dependency>

生产者代码 

public static void main(String[] args) {
	DefaultMQProducer defaultProducer = getDefaultProducer();
	Producer producer = new Producer();
	producer.Sync(defaultProducer);
	producer.Async(defaultProducer);
	producer.oneway(defaultProducer);
	defaultProducer.shutdown();
}
public static DefaultMQProducer getDefaultProducer() {
	try {
		DefaultMQProducer producer = new DefaultMQProducer("producerGroup");
		producer.setNamesrvAddr("localhost:9876");
		producer.start();
		return producer;
	} catch (Exception e) {
		e.printStackTrace();
		return null;
	}
}
/**
 * 同步发送
 * @param producer
 */
public void Sync(DefaultMQProducer producer) {
	try {
		// 同步消息发送失败后，重新发送几次
		producer.setRetryTimesWhenSendFailed(0);
		Message msg = new Message("topic", "同步发送".getBytes());
		SendResult res = producer.send(msg);
		System.out.println("res" + res);
	} catch (Exception e) {
		e.printStackTrace();
	}
}
/**
 * 异步发送
 * @param producer
 */
public void Async(DefaultMQProducer producer) {
	try {
		// 异步消息发送失败后，重新发送几次
		producer.setRetryTimesWhenSendAsyncFailed(0);
		Message msg = new Message("topic", "异步消息".getBytes());
		producer.send(msg, new SendCallback() {
			@Override
			public void onSuccess(SendResult sendResult) {
				System.out.println("sendResult:" + sendResult);
			}
			@Override
			public void onException(Throwable throwable) {
				System.out.println("throwable:" + throwable);
			}
		});
	} catch (Exception e) {
		e.printStackTrace();
	}
}
/**
 * 单向发送
 * @param producer
 */
public void oneway(DefaultMQProducer producer) {
	try {
		Message msg = new Message("topic", "单向发送".getBytes());
		producer.sendOneway(msg);
	}catch (Exception e) {
		e.printStackTrace();
	}
}

三种发送模式的区别

同步发送：消息发送到master broker后并同步到slave broker后，才会响应客户端，效率慢，但丢失数据的风险小

异步发送：消息发送到master broker后就响应客户端，无需等待成功同步到slave broker，效率高，风险也高。例如master broker处理完消息后，响应完客户端后，未同步到slave broker

单向发送：生产者只需要生产消息，无需broker返回结果，效率最快，风险也最高，适用于允许丢失消息的场景中