一、常用Producer类

最常用的producer类就是DefaultMQProducer,具体使用看下文

二、DefaultMQProducer的消息发送步骤

  1. 设置 ProducerGroupName
  2. 设置 lnstanceName
  3. 设置发送失败重试次数
  4. 设置 NameServer 地址
  5. 组装消息并发送

具体代码参考如下:

package org.apache.rocketmq.example.simple;

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;

public class Producer {
    public static void main(String[] args) throws MQClientException, InterruptedException {

        DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");
        producer.setInstanceName("p1");
        producer.setRetryTimesWhenSendFailed(3);
        producer.setNamesrvAddr("192.128.122.123:9876;192.128.122.124:9876;");

        producer.start();

        for (int i = 0; i < 128; i++)
            try {
                {
                    Message msg = new Message("TopicTest",
                        "TagA",
                        "OrderID188",
                        "Hello world".getBytes(RemotingHelper.DEFAULT_CHARSET));
                    SendResult sendResult = producer.send(msg);
                    System.out.printf("%s%n", sendResult);
                }

            } catch (Exception e) {
                e.printStackTrace();
            }

        producer.shutdown();
    }
}

三、消息发送方式

1.同步发送
DefaultMQProducer同步发送消息可参考如下代码,需要注意的是send方法的返回值:

SEND_OK
FLUSH_DISK_TIMEOUT
FLUSH_SLAVE_TIMEOUT
SLAVE_NOT_AVAILABLE
需要结合配置的刷盘策略、主从策略来理解其含义
package org.apache.rocketmq.example.simple;

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;

public class Producer {
    public static void main(String[] args) throws MQClientException, InterruptedException {

        DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");

        producer.start();

        for (int i = 0; i < 128; i++)
            try {
                {
                    Message msg = new Message("TopicTest",
                        "TagA",
                        "OrderID188",
                        "Hello world".getBytes(RemotingHelper.DEFAULT_CHARSET));
                    SendResult sendResult = producer.send(msg);
                    System.out.printf("%s%n", sendResult);
                }

            } catch (Exception e) {
                e.printStackTrace();
            }

        producer.shutdown();
    }
}

2.异步发送
DefaultMQProducer异步发送消息可参考如下代码:

package org.apache.rocketmq.example.simple;

import java.io.UnsupportedEncodingException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.client.producer.DefaultMQProducer;
import org.apache.rocketmq.client.producer.SendCallback;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.remoting.common.RemotingHelper;

public class AsyncProducer {
    public static void main(
        String[] args) throws MQClientException, InterruptedException, UnsupportedEncodingException {

        DefaultMQProducer producer = new DefaultMQProducer("Jodie_Daily_test");
        producer.start();
        producer.setRetryTimesWhenSendAsyncFailed(0);

        int messageCount = 100;
        final CountDownLatch countDownLatch = new CountDownLatch(messageCount);
        for (int i = 0; i < messageCount; i++) {
            try {
                final int index = i;
                Message msg = new Message("Jodie_topic_1023",
                    "TagA",
                    "OrderID188",
                    "Hello world".getBytes(RemotingHelper.DEFAULT_CHARSET));
                producer.send(msg, new SendCallback() {
                    @Override
                    public void onSuccess(SendResult sendResult) {
                        countDownLatch.countDown();
                        System.out.printf("%-10d OK %s %n", index, sendResult.getMsgId());
                    }

                    @Override
                    public void onException(Throwable e) {
                        countDownLatch.countDown();
                        System.out.printf("%-10d Exception %s %n", index, e);
                        e.printStackTrace();
                    }
                });
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        countDownLatch.await(5, TimeUnit.SECONDS);
        producer.shutdown();
    }
}

3.延迟发送
DefaultMQProducer延迟发送使用方法:

在创建 Message对象时,调用 setDelayTimeLevel ( int level) 方法设置延迟时间,然后send

注意:

延迟发送仅支持预设值的时间长度:1s/5s/1Os/30s/Im/2m/3m/4m/5m/6m/ 7m/8m/9m/1Om/20m/30m/1h/2h
如setDelayTimeLevel(3)表示延迟 10s

4.事务消息发送
DefaultMQProducer事务消息的发送,结合一个银行转账的场景来说更容易理解。

场景:
A 银行的某账户要转一万元到 B 银行 的某账户 。 A 银 行发送“ B 银行账户增加 一万元” 这个消息,要和“从 A 银行账户扣除一万元” 这个操作同时成功或者同时失败 。

TransactionMQProducer 处理流程是:
1.先发一个“准备从 B 银行账户增加一万元”的消息,发送成功后 ,进行“从 A 银行账户扣除一万元”的操作A。
2.根据操作A结果是否成功,向 RocketMQ发送二次确认( Commit或 是 Rollback) 消息
3.RocketMQ收到 Commit状态则将第一阶段消息标记为可投递,订阅方将能够收到该消息;收到 Rollback 状态则删除第一阶段的消息,订阅方接收不到该消息 。
若二次确认未到达RocketMQ,则发起回查请求

详细参考代码如下:

TransactionProducer

package org.apache.rocketmq.example.transaction;

import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.client.producer.TransactionListener;
import org.apache.rocketmq.client.producer.TransactionMQProducer;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.remoting.common.RemotingHelper;

import java.io.UnsupportedEncodingException;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class TransactionProducer {
    public static void main(String[] args) throws MQClientException, InterruptedException {
        TransactionListener transactionListener = new TransactionListenerImpl();
        TransactionMQProducer producer = new TransactionMQProducer("please_rename_unique_group_name");
        ExecutorService executorService = new ThreadPoolExecutor(2, 5, 100, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(2000), new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
                Thread thread = new Thread(r);
                thread.setName("client-transaction-msg-check-thread");
                return thread;
            }
        });

        producer.setExecutorService(executorService);
        producer.setTransactionListener(transactionListener);
        producer.start();

        String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
        for (int i = 0; i < 10; i++) {
            try {
                Message msg =
                    new Message("TopicTest1234", tags[i % tags.length], "KEY" + i,
                        ("Hello RocketMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
                SendResult sendResult = producer.sendMessageInTransaction(msg, null);
                System.out.printf("%s%n", sendResult);

                Thread.sleep(10);
            } catch (MQClientException | UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }

        for (int i = 0; i < 100000; i++) {
            Thread.sleep(1000);
        }
        producer.shutdown();
    }
}

TransactionListenerImpl

package org.apache.rocketmq.example.transaction;

import org.apache.rocketmq.client.producer.LocalTransactionState;
import org.apache.rocketmq.client.producer.TransactionListener;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageExt;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

public class TransactionListenerImpl implements TransactionListener {
    private AtomicInteger transactionIndex = new AtomicInteger(0);

    private ConcurrentHashMap<String, Integer> localTrans = new ConcurrentHashMap<>();

    @Override
    public LocalTransactionState executeLocalTransaction(Message msg, Object arg) {
        int value = transactionIndex.getAndIncrement();
        int status = value % 3;
        localTrans.put(msg.getTransactionId(), status);
        return LocalTransactionState.UNKNOW;
    }

    @Override
    public LocalTransactionState checkLocalTransaction(MessageExt msg) {
        Integer status = localTrans.get(msg.getTransactionId());
        if (null != status) {
            switch (status) {
                case 0:
                    return LocalTransactionState.UNKNOW;
                case 1:
                    return LocalTransactionState.COMMIT_MESSAGE;
                case 2:
                    return LocalTransactionState.ROLLBACK_MESSAGE;
                default:
                    return LocalTransactionState.COMMIT_MESSAGE;
            }
        }
        return LocalTransactionState.COMMIT_MESSAGE;
    }
}

四、自定义消息发送规则

背景:

一个 Topic会有多个 Message Queue,如果使用 Producer的默认配置,roducer 会轮流向各个 Message Queue 发送消息 。
若业务需要我们把消息发送到指定的 Message Queue里,可以使用MessageQueueSelector

解决思路:

发送消息的时候,将 MessageQueueSelector 的对象作为参数,
在 MessageQueueSelector 实现中,根据传入的 Object参 数,或者Message 消息内容确定把消息发往哪个 Message Queue,然后返回被选中的 Message Queue。

使用public SendResult send(Message msg, MessageQueueSelector selector, Object arg)函数发送消息

具体参考代码如下:

package org.apache.rocketmq.example.ordermessage;

import java.io.UnsupportedEncodingException;
import java.util.List;
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.MQProducer;
import org.apache.rocketmq.client.producer.MessageQueueSelector;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.common.RemotingHelper;
import org.apache.rocketmq.remoting.exception.RemotingException;

public class Producer {
    public static void main(String[] args) throws UnsupportedEncodingException {
        try {
            MQProducer producer = new DefaultMQProducer("please_rename_unique_group_name");
            producer.start();

            String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
            for (int i = 0; i < 100; i++) {
                int orderId = i % 10;
                Message msg =
                    new Message("TopicTestjjj", tags[i % tags.length], "KEY" + i,
                        ("Hello RocketMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
                SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
                    @Override
                    public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
                        Integer id = (Integer) arg;
                        int index = id % mqs.size();
                        return mqs.get(index);
                    }
                }, orderId);

                System.out.printf("%s%n", sendResult);
            }

            producer.shutdown();
        } catch (MQClientException | RemotingException | MQBrokerException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}