import java.util.concurrent.TimeUnit;
import com.alibaba.rocketmq.client.exception.MQClientException;
import com.alibaba.rocketmq.client.producer.DefaultMQProducer;
import com.alibaba.rocketmq.client.producer.SendResult;
import com.alibaba.rocketmq.common.message.Message;
public class Producer {
public static void main(String[] args) throws MQClientException, InterruptedException {
/**
* 一个应用创建一个Producer，由应用来维护此对象，可以设置为全局对象或者单例
* 注意：ProducerGroupName需要由应用来保证唯一
* ProducerGroup这个概念发送普通的消息时，作用不大，但是发送分布式事务消息时，比较关键，
* 因为服务器会回查这个Group下的任意一个Producer
*/
final DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");
producer.setNamesrvAddr("172.30.2.27:9886");
producer.setInstanceName("Producer");
/**
* Producer对象在使用之前必须要调用start初始化，初始化一次即可
* 注意：切记不可以在每次发送消息时，都调用start方法
*/
producer.start();
/**
* 下面这段代码表明一个Producer对象可以发送多个topic，多个tag的消息。
* 注意：send方法是同步调用，只要不抛异常就标识成功。但是发送成功也可会有多种状态，
* 例如消息写入Master成功，但是Slave不成功，这种情况消息属于成功，但是对于个别应用如果对消息可靠性要求极高，
* 需要对这种情况做处理。另外，消息可能会存在发送失败的情况，失败重试由应用来处理。
*/
for (int i = 0; i < 10; i++) {
try {
{
Message msg = new Message("TopicTest1", // topic
"TagA", // tag ，
"OrderID001", // key ， 最好用唯一的编号，比如订单号码？交易流水号？
("Hello MetaQA").getBytes());// body , 实际应用场景中可以使用Json数据字符串，传递相应的内容
SendResult sendResult = producer.send(msg);
System.out.println(sendResult);
}
{
Message msg = new Message("TopicTest2", // topic
"TagB", // tag
"OrderID0034", // key
("Hello MetaQB").getBytes());// body
SendResult sendResult = producer.send(msg);
System.out.println(sendResult);
}
{
Message msg = new Message("TopicTest3", // topic
"TagC", // tag
"OrderID061", // key
("Hello MetaQC").getBytes());// body
SendResult sendResult = producer.send(msg);
System.out.println(sendResult);
}
} catch (Exception e) {
e.printStackTrace();
}
TimeUnit.MILLISECONDS.sleep(1000);
}
/**
* 应用退出时，要调用shutdown来清理资源，关闭网络连接，从MetaQ服务器上注销自己
* 注意：我们建议应用在JBOSS、Tomcat等容器的退出钩子里调用shutdown方法
*/
// producer.shutdown();
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
public void run() {
producer.shutdown();
}
}));
System.exit(0);
}
}
调用原理图：
分析源码：
producer.send(msg);这段代码底层调用一下方法（发送消息超时时间默认sendMsgTimeout = 3000）：
public SendResult send(Message msg, long timeout) throws MQClientException, RemotingException,
MQBrokerException, InterruptedException {
return this.sendDefaultImpl(msg, CommunicationMode.SYNC, null, timeout);
}具体实现：
private SendResult sendDefaultImpl(//
Message msg,//
final CommunicationMode communicationMode,//
final SendCallback sendCallback, final long timeout//
) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
this.makeSureStateOK();
Validators.checkMessage(msg, this.defaultMQProducer);
final long maxTimeout = this.defaultMQProducer.getSendMsgTimeout() + 1000;
final long beginTimestamp = System.currentTimeMillis();
long endTimestamp = beginTimestamp;
TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
if (topicPublishInfo != null && topicPublishInfo.ok()) {
MessageQueue mq = null;
Exception exception = null;
SendResult sendResult = null;
int timesTotal = 1 + this.defaultMQProducer.getRetryTimesWhenSendFailed();
int times = 0;
String[] brokersSent = new String[timesTotal];
for (; times < timesTotal && (endTimestamp - beginTimestamp) < maxTimeout; times++) {
String lastBrokerName = null == mq ? null : mq.getBrokerName();
MessageQueue tmpmq = topicPublishInfo.selectOneMessageQueue(lastBrokerName);
if (tmpmq != null) {
mq = tmpmq;
brokersSent[times] = mq.getBrokerName();
try {
sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, timeout);
endTimestamp = System.currentTimeMillis();
switch (communicationMode) {
case ASYNC:
return null;
case ONEWAY:
return null;
case SYNC:
if (sendResult.getSendStatus() != SendStatus.SEND_OK) {
if (this.defaultMQProducer.isRetryAnotherBrokerWhenNotStoreOK()) {
continue;
}
}
return sendResult;
default:
break;
}
}
catch (RemotingException e) {
log.warn("sendKernelImpl exception", e);
log.warn(msg.toString());
exception = e;
endTimestamp = System.currentTimeMillis();
continue;
}
catch (MQClientException e) {
log.warn("sendKernelImpl exception", e);
log.warn(msg.toString());
exception = e;
endTimestamp = System.currentTimeMillis();
continue;
}
catch (MQBrokerException e) {
log.warn("sendKernelImpl exception", e);
log.warn(msg.toString());
exception = e;
endTimestamp = System.currentTimeMillis();
switch (e.getResponseCode()) {
case ResponseCode.TOPIC_NOT_EXIST:
case ResponseCode.SERVICE_NOT_AVAILABLE:
case ResponseCode.SYSTEM_ERROR:
case ResponseCode.NO_PERMISSION:
case ResponseCode.NO_BUYER_ID:
case ResponseCode.NOT_IN_CURRENT_UNIT:
continue;
default:
if (sendResult != null) {
return sendResult;
}
throw e;
}
}
catch (InterruptedException e) {
log.warn("sendKernelImpl exception", e);
log.warn(msg.toString());
throw e;
}
}
else {
break;
}
} // end of for
if (sendResult != null) {
return sendResult;
}
String info =
String.format("Send [%d] times, still failed, cost [%d]ms, Topic: %s, BrokersSent: %s", //
times, //
(System.currentTimeMillis() - beginTimestamp), //
msg.getTopic(),//
Arrays.toString(brokersSent));
info += FAQUrl.suggestTodo(FAQUrl.SEND_MSG_FAILED);
throw new MQClientException(info, exception);
}
List nsList = this.getmQClientFactory().getMQClientAPIImpl().getNameServerAddressList();
if (null == nsList || nsList.isEmpty()) {
throw new MQClientException("No name server address, please set it."
+ FAQUrl.suggestTodo(FAQUrl.NAME_SERVER_ADDR_NOT_EXIST_URL), null);
}
throw new MQClientException("No route info of this topic, " + msg.getTopic()
+ FAQUrl.suggestTodo(FAQUrl.NO_TOPIC_ROUTE_INFO), null);
}