RocketMQ学习笔记(6)----RocketMQ的Client的使用 Producer/Consumer

1.  添加依赖

  pom.xml如下:

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 <dependency>
      <groupId>org.apache.rocketmq</groupId>
      <artifactId>rocketmq-client</artifactId>
      <version>4.3.1</version>
    </dependency>
    <dependency>
      <groupId>org.apache.rocketmq</groupId>
      <artifactId>rocketmq-srvutil</artifactId>
      <version>4.3.1</version>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>1.2.3</version>
    </dependency>
    <dependency>
      <groupId>org.javassist</groupId>
      <artifactId>javassist</artifactId>
        <version>3.23.1-GA</version>
    </dependency>
    <dependency>
      <groupId>io.openmessaging</groupId>
      <artifactId>openmessaging-api</artifactId>
      <version>0.3.0-alpha</version>
    </dependency>
    <dependency>
      <groupId>org.apache.rocketmq</groupId>
      <artifactId>rocketmq-openmessaging</artifactId>
      <version>4.3.1</version>
    </dependency>
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2. Producer 的开发步骤

  1. 实例化Producer Group,如下:

  DefaultMQProducer producer = new DefaultMQProducer("my-producer-group");

  2. 设置namesrvAddr,集群环境多个nameserver用;分割,如下:

producer.setNamesrvAddr("47.105.145.123:9876;47.105.149.61:9876");

  3. 调用start()方法启动:

 producer.start();

  4. 发送消息

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 for (int i = 0; i < 10; i++) {
            //构建实例,第一个参数为topic,第二个参数为tabs,第三个参数为消息体
            Message message = new Message("MyQuickStartTopic","tabA",("Hello World:" + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
            SendResult result = producer.send(message);
            System.out.println(result);
        }
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  5. 关闭生产者(根据自己需求确定是够需要关闭)

 producer.shutdown();

  完整示例如下:

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package com.wangx.rocketmq.quickstart;

import org.apache.rocketmq.client.exception.MQBrokerException;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.client.producer.DefaultMQProducer;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.remoting.common.RemotingHelper;
import org.apache.rocketmq.remoting.exception.RemotingException;

import java.io.UnsupportedEncodingException;

/**
 * 创建一个消费者
 */
public class Producer {

    public static void main(String[] args) throws MQClientException, RemotingException, InterruptedException, MQBrokerException, UnsupportedEncodingException {
        //1. 实例化一个producer group
        DefaultMQProducer producer = new DefaultMQProducer("my-producer-group");

        //2. 设置namesrvAddr,集群环境多个nameserver用;分割

        producer.setNamesrvAddr("47.105.145.123:9876;47.105.149.61:9876");
        //3. 启动
        producer.start();
        // 4. 发送消息
        for (int i = 0; i < 10; i++) {
            //构建实例,第一个参数为topic,第二个参数为tabs,第三个参数为消息体
            Message message = new Message("MyQuickStartTopic","tabA",("Hello World:" + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
            SendResult result = producer.send(message);
            System.out.println(result);
        }
        //关闭生产者
        producer.shutdown();

    }
}
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  使用方式可以说非常简单了。

3. Consumer开发步骤

  1. 实例化Consumer Group,如下:

DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("my-consumer-group");

  2. 设置namesrvAddr,集群环境多个nameserver用;分割,如下:

producer.setNamesrvAddr("47.105.145.123:9876;47.105.149.61:9876");

  3. 设置从什么位置开始都

consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_LAST_OFFSET);

  4. 订阅topic.

consumer.subscribe("MyQuickStartTopic", "*");

  5. 注册消息监听器

 consumer.registerMessageListener();

  6. 重写MessageListenerConcurrently接口的consumeMessage()方法

  完整代码如下:

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package com.wangx.rocketmq.quickstart;

import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus;
import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.common.consumer.ConsumeFromWhere;
import org.apache.rocketmq.common.message.MessageExt;

import java.util.List;

/**
 * 创建一个消费者
 */
public class Consumer {
    public static void main(String[] args) throws MQClientException {
        //实例化一个consumer组
        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("my-consumer-group");
        //设置setNamesrvAddr,同生产者
        consumer.setNamesrvAddr("47.105.145.123:9876;47.105.149.61:9876");

        //设置消息读取方式,这里设置的是队尾开始读取
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_LAST_OFFSET);

        //设置订阅主题,第二个参数为过滤tabs的条件,可以写为tabA|tabB过滤Tab,*表示接受所有
        consumer.subscribe("MyQuickStartTopic", "*");

        //注册消息监听
        consumer.registerMessageListener(new MessageListenerConcurrently() {
            @Override
            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> list, ConsumeConcurrentlyContext consumeConcurrentlyContext) {
                try {
                    //的到MessageExt
                    MessageExt messageExt = list.get(0);
                    String topic = messageExt.getTopic();
                    String message = new String(messageExt.getBody(),"UTF-8");
                    int queueId = messageExt.getQueueId();
                    System.out.println("收到来自topic:" + topic + ", queueId:" + queueId + "的消息:" + message);

                } catch (Exception e) {
                    //失败,请求稍后重发
                    return ConsumeConcurrentlyStatus.RECONSUME_LATER;
                }
                //成功
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });
        consumer.start();

    }
}
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  consumeMessage返回一个枚举的两种状态,成功表示接受成功,否则返回稍后重发的状态。这里注意,启动的时候需要consumer先启动,因为它需要在生产者之前先订阅,否则将会收不到生产在consumer生产的消息,造成消息丢失。

  启动consumer,在启动producer

  producer控制台

  consumer控制台:

  rocketmq-console信息:

可以看到,我们前面部署的集群环境也是能够实现消息的负载均衡的,会使两个broker上都创建topic,且都能够接收生产者生产的消息。

  进入topic,可以看到新增了两个我们自定义的topic

可能会出现的问题:

  RemotingTooMuchRequestException: sendDefaultImpl call timeout

  在客户端运行Producer时,可能会出现如上异常,这是因为从 Windows 上开发连接 虚拟机中的 nameServer 时要经过 Linux 系统的防火墙,而防火墙一般都会有超时的机制,在网络连接长时间不传输数据时,会关闭这个 TCP 的会话,关闭后再读写,就有可能导致这个异常。

  解决办法就是关闭防火墙,ubuntu下命令如下:

  

  contOS下命令如下:

  systemctl stop firewalld.service #停止firewall
  systemctl disable firewalld.service #禁止firewall开机启动
  firewall-cmd --state #查看默认防火墙状态(关闭后显示notrunning,开启后显示running)

原文 RocketMQ学习笔记(6)----RocketMQ的Client的使用 Producer/Consumer

posted @ 2019-05-15 09:35  xiaoshen666  阅读(2663)  评论(0编辑  收藏  举报