RocetMQ发送顺序消息的所有方法以及代码示例

一、使用RocketMQTemplate发送顺序消息

关于什么是顺序消息，可以参考这篇文章：RocketMQ的顺序消息（顺序消费），这里主要讲如何使用RocketMQ发送顺序消息。

（1）SendResult syncSendOrderly(String destination, Message message, String hashKey);同步发送

import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Message<String> sendMessage = MessageBuilder.withPayload("这里些消息体")
                .setHeader("消息属性的键","消息属性的值")
                .setHeader("KEYS", "消息的key")
                .build();
        SendResult sendResult = rocketMQTemplate.syncSendOrderly("topicA:tagA", sendMessage, "hashKey");
        System.out.println(sendResult);
    }
}

相对于发送普通消息，发送顺序消息的关键是设置hashKey这个参数。接下来浅显的讲一下实现顺序消息的原理。如下是RocketMQ发送顺序消息的部分源码：

import java.util.List;
import org.apache.rocketmq.client.producer.MessageQueueSelector;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;

public class SelectMessageQueueByHash implements MessageQueueSelector {
    public SelectMessageQueueByHash() {
    }

    public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
        int value = arg.hashCode() % mqs.size();
        if (value < 0) {
            value = Math.abs(value);
        }

        return (MessageQueue)mqs.get(value);
    }
}

通过源码可以看到，RocketMQ会获取每个Java对象都有的hashCode来对queue的数量取模，如果取模后得到的值小于0则取绝对值，最后根据取模后的值去集合中获取一个queue。然后消息就发送到这个queue中。

每个topic都有1-16个queue，queue的数量是在创建topic时设定的，每个消息会负载均衡地发送到这些queue中的其中一个。顺序消息的原理就是使需要保证顺序的消息都发送到同一个queue，从而保证顺序。这里对底层原理不做过多的说明。

hashKey相同的消息被保证发送到topic下相同的queue从而实现顺序消息。实际工作中，hashKey往往被设为订单ID，交易ID等从而保证相同订单ID的消息的顺序。

（2）SendResult syncSendOrderly(String destination, Message message, String hashKey, long timeout);同步发送

import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Message<String> sendMessage = MessageBuilder.withPayload("这里设置消息体")
                .setHeader("消息属性的键","消息属性的值")
                .setHeader("KEYS", "消息的key")
                .build();
        SendResult sendResult = rocketMQTemplate.syncSendOrderly("topicA:tagA", sendMessage, "hashKey", 3000L);
        System.out.println(sendResult);
    }
}

相对于方法（1）增加了timeout来设置超时时间。

（3）SendResult syncSendOrderly(String destination, Object payload, String hashKey);同步发送

import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        SendResult sendResult = rocketMQTemplate.syncSendOrderly("topicA:tagA", "这里设置消息体", "hashKey");
        System.out.println(sendResult);
    }
}

相对于方法（1），第二个参数变成了Object类型，我们可以直接传入字符串或者实体类，RocketMQ会在底层帮我们转化成Message对象。此方法的缺点是不能设置消息的属性和key。

（4）SendResult syncSendOrderly(String destination, Object payload, String hashKey, long timeout);同步发送

import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        SendResult sendResult = rocketMQTemplate.syncSendOrderly("topicA:tagA", "这里设置消息体", "hashKey", 3000L);
        System.out.println(sendResult);
    }
}

相对于方法（3）增加了timeout来设置超时时间。

（5） SendResult syncSendOrderly(String destination, Collection messages, String hashKey);同步发送

import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

import java.util.ArrayList;
import java.util.Collection;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Collection<Message<String>> messages = new ArrayList<>();
        for (int i=0; i<3; i++) {
            Message<String> sendMessage = MessageBuilder.withPayload("这里设置消息体" + i)
                    .setHeader("消息属性的键","消息属性的值")
                    .setHeader("KEYS", "消息的key")
                    .build();
            messages.add(sendMessage);
        }
        SendResult sendResult = rocketMQTemplate.syncSendOrderly("topicA:tagA", messages, "hashKey");
        System.out.println(sendResult);
    }
}

批量发送顺序消息。

（6） SendResult syncSendOrderly(String destination, Collection messages, String hashKey, long timeout);同步发送

import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

import java.util.ArrayList;
import java.util.Collection;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Collection<Message<String>> messages = new ArrayList<>();
        for (int i=0; i<3; i++) {
            Message<String> sendMessage = MessageBuilder.withPayload("这里设置消息体" + i)
                    .setHeader("消息属性的键","消息属性的值")
                    .setHeader("KEYS", "消息的key")
                    .build();
            messages.add(sendMessage);
        }
        SendResult sendResult = rocketMQTemplate.syncSendOrderly("topicA:tagA", messages, "hashKey", 3000L);
        System.out.println(sendResult);
    }
}

相对于方法（5）增加了timeout来设置超时时间。

（7）void asyncSendOrderly(String destination, Message message, String hashKey, SendCallback sendCallback);异步发送

import org.apache.rocketmq.client.producer.SendCallback;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Message<String> sendMessage = MessageBuilder.withPayload("这里设置消息体")
                .setHeader("消息属性的键","消息属性的值")
                .setHeader("KEYS", "消息的key")
                .build();
        rocketMQTemplate.asyncSendOrderly("topicA:tagA", sendMessage, "hashKey", new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        });
    }
}

相对于同步发送顺序消息，异步发送只是多了一个SendCallback参数。注意：异步发送顺序消息并不能严格保证消息的顺序。

异步发送模式在消息发送后立刻返回，当消息完全完成发送后，会调用回调函数sendCallback来告知发送者本次发送是成功或者失败。异步模式通常用于响应时间敏感业务场景，即承受不了同步发送消息时等待返回的耗时代价。

（8）void asyncSendOrderly(String destination, Message message, String hashKey, SendCallback sendCallback, long timeout);异步发送

import org.apache.rocketmq.client.producer.SendCallback;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Message<String> sendMessage = MessageBuilder.withPayload("这里设置消息体")
                .setHeader("消息属性的键","消息属性的值")
                .setHeader("KEYS", "消息的key")
                .build();
        rocketMQTemplate.asyncSendOrderly("topicA:tagA", sendMessage, "hashKey", new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        }, 3000L);
    }
}

相对于方法（7）增加了timeout来设置超时时间。

（9）void asyncSendOrderly(String destination, Object payload, String hashKey, SendCallback sendCallback);异步发送

import org.apache.rocketmq.client.producer.SendCallback;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        rocketMQTemplate.asyncSendOrderly("topicA:tagA", "这里设置消息体", "hashKey", new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        });
    }
}

相对于方法（7），第二个参数变成了Object类型，我们可以直接传入字符串或者实体类，RocketMQ会在底层帮我们转化成Message对象。此方法的缺点是不能设置消息的属性和key。

（10）void asyncSendOrderly(String destination, Object payload, String hashKey, SendCallback sendCallback, long timeout);异步发送

import org.apache.rocketmq.client.producer.SendCallback;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        rocketMQTemplate.asyncSendOrderly("topicA:tagA", "这里设置消息体", "hashKey", new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        }, 3000L);
    }
}

相对于方法（9）增加了timeout来设置超时时间。

（11）void sendOneWayOrderly(String destination, Message message, String hashKey);one-way模式，异步发送

import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        Message<String> sendMessage = MessageBuilder.withPayload("这里些消息体")
                .setHeader("消息属性的键","消息属性的值")
                .setHeader("KEYS", "消息的key")
                .build();
        rocketMQTemplate.sendOneWayOrderly("topicA:tagA", sendMessage, "hashKey");
    }
}

使用one-way模式发送顺序消息。本质上是讲SendCallback设为null的异步发送消息。注意：异步发送顺序消息并不能严格保证消息的顺序。

采用one-way发送模式发送消息的时候，发送端发送完消息后会立即返回，不会等待来自broker的ack来告知本次消息发送是否完全完成发送。这种模式吞吐量很大，但是存在消息丢失的风险，所以其适用于不重要的消息发送，比如日志收集。one-way模式本质上是没有sendCallback的异步发送方式。

（12）void sendOneWayOrderly(String destination, Object payload, String hashKey);one-way模式，异步发送

import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;

public class OrderlyMessageProducer {
    @Autowired
    RocketMQTemplate rocketMQTemplate;
    public void sendMessages() {
        rocketMQTemplate.sendOneWayOrderly("topicA:tagA", "这里设置消息体", "hashKey");
    }
}

相对于方法（11）第二个参数变成了Object类型，我们可以直接传入字符串或者实体类，RocketMQ会在底层帮我们转化成Message对象。此方法的缺点是不能设置消息的属性和key。

综上所述，使用RocketMQTemplate发送顺序消息相对与发送普通消息只是多了一个hashKey参数，详细的如何使用RocketMQTemplate发送普通消息可以参考我的另一篇文章：RocketMQ发送普通消息的所有方法以及代码示例。值得注意的是，异步发送顺序消息并不能严格保证消息的顺序。

二、使用DefaultMQProducer发送顺序消息

DefaultMQProducer有多个构造函数，我们可以根据不同的场景使用不同的构造函数创建对象。

2.1 DefaultMQProducer的创建

（1）DefaultMQProducer(String namespace, String producerGroup, RPCHook rpcHook);

DefaultMQProducer producer = new DefaultMQProducer("命名空间", "生产者组", new AclClientRPCHook(new SessionCredentials("用户名","密码")));

此构造函数的第一个参数是命名空间，命名空间需要在服务端提前创建。第二个参数是生产者组，一个生产者组可以包含多个生产者，生产者组不需要提前创建，在创建DefaultMQProducer对象的时候赋值一个生产者组就可以。第三个参数是RPCHook对象用于权限认证，相当于你登陆一个网站需要输入用户名和密码。

命名空间是RocketMQ中的一个资源管理概念。用户不同的业务场景一般都可以通过命名空间做隔离，并且针对不同的业务场景设置专门的配置，例如消息保留时间。不同命名空间之间的 Topic 相互隔离，订阅相互隔离，角色权限相互隔离。

（2）DefaultMQProducer(String producerGroup, RPCHook rpcHook);

DefaultMQProducer producer = new DefaultMQProducer("生产者组", new AclClientRPCHook(new SessionCredentials("用户名","密码")));

此构造函数底层还是调用了构造方法（1），只不过将namespace设为了null，在没有命名空间的时候可以使用此构造函数。

（3）DefaultMQProducer(String namespace, String producerGroup);

DefaultMQProducer producer = new DefaultMQProducer("命名空间", "生产者组");

此构造函数底层还是调用了构造方法（1），只不过将RPCHook 设为了null，在不需要acl认证的时候可以使用此构造函数。

（4）DefaultMQProducer(String producerGroup);

DefaultMQProducer producer = new DefaultMQProducer("生产者组");

此构造函数底层还是调用了构造方法（1），只不过将namespace和RPCHook设为了null，在没有命名空间和不需要acl认证的时候可以使用此构造函数。

（5）DefaultMQProducer(RPCHook rpcHook);

DefaultMQProducer producer = new DefaultMQProducer(new AclClientRPCHook(new SessionCredentials("用户名","密码")));

此构造函数底层还是调用了构造方法（1），只不过将namespace设为了null，由于prodcuerGroup不能为null，所以RocketMQ会使用默认的生产者组：DEFAULT_PRODUCER。

（6）DefaultMQProducer();

DefaultMQProducer producer = new DefaultMQProducer();

此构造函数底层还是调用了构造方法（1），只不过将namespace和RPCHook设为了null，由于prodcuerGroup不能为null，所以RocketMQ会使用默认的生产者组：DEFAULT_PRODUCER。

（7）DefaultMQProducer(String namespace, String producerGroup, RPCHook rpcHook, boolean enableMsgTrace, String customizedTraceTopic);

DefaultMQProducer producer = new DefaultMQProducer("命名空间", "生产者组", new AclClientRPCHook(new SessionCredentials("用户名","密码")), true, "traceTopic");

此构造函数的第一个参数是命名空间，命名空间需要在服务端提前创建。第二个参数是生产者组，一个生产者组可以包含多个生产者，生产者组不需要提前创建，在创建DefaultMQProducer对象的时候赋值一个生产者组就可以。第三个参数是RPCHook对象用于权限认证，相当于你登陆一个网站需要输入用户名和密码。第四个参数是布尔类型，表示是否开启消息追踪。第五个参数是消息跟踪的topic的名称，这个topic专门用来做消息追踪的，一般不会用这个topic生产和消费业务数据。开启追踪后，追踪topic内会记录生产者的一些信息，比如生产者IP、消息的MessageID等。例如下面的代码就是开启追踪并设置trace-topic为追踪topic，然后将消息发送到topicA中，于是topicA里面是业务数据，trace-topic里面是用于消息追踪的追踪数据。也就是发送一次消息会发送一份业务数据和一份追踪数据到业务topic和追踪topic，

package com.sgm.esb.gateway.service;

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.common.message.Message;
import org.apache.rocketmq.remoting.exception.RemotingException;

import java.nio.charset.StandardCharsets;


public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");

        producer.start();
        Message sendMessage = new Message("topicA", "tagA", "这里设置消息体".getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");

        producer.send(sendMessage);

        producer.shutdown();
    }
}

如下是追踪topic中的消息内容：

（8）DefaultMQProducer(String producerGroup, boolean enableMsgTrace, String customizedTraceTopic);

DefaultMQProducer producer = new DefaultMQProducer("生产者组", true, "traceTopic");

此构造函数底层还是调用了构造方法（7），只不过将namespace和RPCHook设为了null，使用于没有命名空间和不需要acl认证的时候。

（9）DefaultMQProducer(String producerGroup, boolean enableMsgTrace);

DefaultMQProducer producer = new DefaultMQProducer("生产者组", true);

此构造函数底层还是调用了构造方法（7），只不过将namespace、RPCHook和customizedTraceTopic设为了null。

2.2 发送顺序消息

（1）SendResult send(Message msg, MessageQueue mq) throws MQClientException, RemotingException, MQBrokerException, InterruptedException;同步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;

import java.nio.charset.StandardCharsets;
import java.util.List;


public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        // fetchPublishMessageQueues()中传入的topic必须和Message设置的topic一致，否则发送消息的时候会报错
        List<MessageQueue> messageQueues = producer.fetchPublishMessageQueues("topicA");
        // 根据需求获取一个MessageQueue
        MessageQueue queue = messageQueues.get(0);
        producer.send(sendMessage, queue);
        producer.shutdown();
    }
}

SendResult send(Message msg, MessageQueue mq)第二个参数是MessageQueue类型，表示一个消息队列，设置了这个参数之后消息都会发到这个队列中去，由于队列这种数据结构具有先进先出的特性，所以可以保证消息的顺序性。我们先使用fetchPublishMessageQueues(String topic)方法获取topicA下的MessageQueue，然后根据实际的需要选取一个queue作为参数传入send()方法中。这样做虽然可以保证顺序，但是如果消息全部都往一个队列中发送和消费，会导致效率非常低下。

（2）SendResult send(Message msg, MessageQueue mq， long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException;同步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;


public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        // fetchPublishMessageQueues()中传入的topic必须和Message设置的topic一致，否则发送消息的时候会报错
        List<MessageQueue> messageQueues = producer.fetchPublishMessageQueues("topicA");
        // 根据需求获取一个MessageQueue
        MessageQueue queue = messageQueues.get(0);
        producer.send(sendMessage, queue, 3000L);
        producer.shutdown();
    }
}

相对于方法（1）增加了timeout来设置超时时间。

（3）void send(Message msg, MessageQueue mq, SendCallback sendCallback) throws MQClientException, RemotingException, InterruptedException;异步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.SendCallback;
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.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        // fetchPublishMessageQueues()中传入的topic必须和Message设置的topic一致，否则发送消息的时候会报错
        List<MessageQueue> messageQueues = producer.fetchPublishMessageQueues("topicA");
        // 根据需求获取一个MessageQueue
        MessageQueue queue = messageQueues.get(0);
        producer.send(sendMessage, queue, new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        });
        producer.shutdown();
    }
}

增加了SendCallback参数表明这个发送方式是异步发送。

（4）void send(Message msg, MessageQueue mq, SendCallback sendCallback, long timeout) throws MQClientException, RemotingException, InterruptedException;异步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.SendCallback;
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.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        // fetchPublishMessageQueues()中传入的topic必须和Message设置的topic一致，否则发送消息的时候会报错
        List<MessageQueue> messageQueues = producer.fetchPublishMessageQueues("topicA");
        // 根据需求获取一个MessageQueue
        MessageQueue queue = messageQueues.get(0);
        producer.send(sendMessage, queue, new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        }, 3000L);
        producer.shutdown();
    }
}

相对于方法（3）增加了timeout来设置超时时间。

（5）void sendOneway(Message msg, MessageQueue mq) throws MQClientException, RemotingException, InterruptedException;one-way模式，异步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        // fetchPublishMessageQueues()中传入的topic必须和Message设置的topic一致，否则会报错
        List<MessageQueue> messageQueues = producer.fetchPublishMessageQueues("topicA");
        // 根据需求获取一个MessageQueue
        MessageQueue queue = messageQueues.get(0);
        producer.sendOneway(sendMessage, queue);
        producer.shutdown();
    }
}

使用one-way模式异步发送消息到某一个队列。

（6）SendResult send(Message msg, MessageQueueSelector selector, Object arg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException;同步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.MessageQueueSelector;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;

import java.nio.charset.StandardCharsets;
import java.util.List;


public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        producer.send(sendMessage, new MessageQueueSelector() {
            @Override
            // select方法的arg参数就是send(Message msg, MessageQueueSelector selector, Object arg)的第三个参数
            public MessageQueue select(List<MessageQueue> list, Message message, Object arg) {
            	// 自定义选取MessageQueue的方法。这里是根据Object的hashCode来选取
                int value =  arg.hashCode() % list.size();
                if (value < 0) {
                    value = Math.abs(value);
                }
                return list.get(value);
            }
        }, "hashKey");
        producer.shutdown();
    }
}

SendResult send(Message msg, MessageQueueSelector selector, Object arg)的第二个参数MessageQueueSelector是一个接口，里面只有MessageQueue select(List list, Message message, Object arg)这一个方法，第一个参数是MessageQueue的列表，第二个参数是send()方法中的msg，第三参数是send()方法中的arg，我们要实现这个接口从而自定义MessageQueue的选择方式。

（7）SendResult send(Message msg, MessageQueueSelector selector, Object arg， long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException;同步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.MessageQueueSelector;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        producer.send(sendMessage, new MessageQueueSelector() {
            @Override
            // select方法的arg参数就是send(Message msg, MessageQueueSelector selector, Object arg)的第三个参数
            public MessageQueue select(List<MessageQueue> list, Message message, Object arg) {
            	// 自定义选取MessageQueue的方法。这里是根据Object的hashCode来选取
                int value =  arg.hashCode() % list.size();
                if (value < 0) {
                    value = Math.abs(value);
                }
                return list.get(value);
            }
        }, "hashKey", 3000L);
        producer.shutdown();
    }
}

相对于方法（6）增加了timeout来设置超时时间。

（8）void send(Message msg, MessageQueueSelector selector, Object arg, SendCallback sendCallback) throws MQClientException, RemotingException, InterruptedException;异步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.MessageQueueSelector;
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.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        producer.send(sendMessage, new MessageQueueSelector() {
            @Override
            public MessageQueue select(List<MessageQueue> list, Message message, Object arg) {
                int value = arg.hashCode() % list.size();
                if (value < 0) {
                    value = Math.abs(value);
                }
                return list.get(value);
            }
        }, "hashKey", new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        });
        producer.shutdown();
    }
}

增加了SendCallback参数表明这个发送方式是异步发送。

（9）void send(Message msg, MessageQueueSelector selector, Object arg, SendCallback sendCallback，long timeout) throws MQClientException, RemotingException, InterruptedException;异步发送

import org.apache.rocketmq.acl.common.AclClientRPCHook;
import org.apache.rocketmq.acl.common.SessionCredentials;
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.MessageQueueSelector;
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.common.message.MessageQueue;
import org.apache.rocketmq.remoting.exception.RemotingException;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class DefaultMQProducerTest {

    public static void main(String[] args) throws MQClientException, MQBrokerException, RemotingException, InterruptedException {
        DefaultMQProducer producer = new DefaultMQProducer("生产者组",
                new AclClientRPCHook(new SessionCredentials("用户名","密码")),
                true, "trace-topic");
        producer.setNamesrvAddr("nameServer集群IP");
        producer.start();
        Message sendMessage = new Message("topicA", "tagA", ("这里设置消息体").getBytes(StandardCharsets.UTF_8));
        sendMessage.putUserProperty("消息的属性的键", "消息的属性的值");
        sendMessage.setKeys("消息的key");
        producer.send(sendMessage, new MessageQueueSelector() {
            @Override
            public MessageQueue select(List<MessageQueue> list, Message message, Object arg) {
                int value = arg.hashCode() % list.size();
                if (value < 0) {
                    value = Math.abs(value);
                }
                return list.get(value);
            }
        }, "hashKey", new SendCallback() {
            @Override
            public void onSuccess(SendResult sendResult) {
                System.out.println("Send success");
            }

            @Override
            public void onException(Throwable throwable) {
                System.out.println("Send fail");
            }
        }, 3000L);
        producer.shutdown();
    }
}

相对于方法（8）增加了timeout来设置超时时间。

总结与展望

使用RocketMQTemplate发送顺序消息相对于发送普通消息只是要设置一下hashKey，hashKey一般设为交易ID、订单ID等。使用DefaultMQProducer发送顺序消息相对于使用RocketMQTemplate我们需要自己实现MessageQueueSelector接口来自定义MessageQueue的选取方式。这是我的第二篇文章，我的第一篇文章《RocketMQ发送普通消息的所有方法以及代码示例》有需要的读者也可以阅读，之后我会继续写关于RocketMQ的文章。