1、订单消息
RocketMQ使用FIFO顺序提供有序消息。
以下示例演示了发送/接收全局和分区排序的消息。
发送消息示例代码
public class OrderedProducer {
public static void main(String[] args) throws Exception {
//Instantiate with a producer group name.
DefaultMQProducer producer = new DefaultMQProducer("example_group_name");
// Specify name server addresses.
producer.setNamesrvAddr("192.168.247.132:9876");
//Launch the instance.
producer.start();
String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
for (int i = 0; i < 100; i++) {
int orderId = i % 10;
//Create a message instance, specifying topic, tag and message body.
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 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);
}
//server shutdown
producer.shutdown();
}
}
订阅消息示例代码
public class OrderedConsumer {
public static void main(String[] args) throws Exception {
DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("example_group_name");
consumer.setNamesrvAddr("192.168.247.132:9876");
consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
consumer.subscribe("TopicTest", "TagA || TagC || TagD");
consumer.registerMessageListener(new MessageListenerOrderly() {
AtomicLong consumeTimes = new AtomicLong(0);
public ConsumeOrderlyStatus consumeMessage(List msgs,
ConsumeOrderlyContext context) {
context.setAutoCommit(false);
System.out.printf(Thread.currentThread().getName() + " Receive New Messages: " + msgs + "%n");
this.consumeTimes.incrementAndGet();
if ((this.consumeTimes.get() % 2) == 0) {
return ConsumeOrderlyStatus.SUCCESS;
} else if ((this.consumeTimes.get() % 3) == 0) {
return ConsumeOrderlyStatus.ROLLBACK;
} else if ((this.consumeTimes.get() % 4) == 0) {
return ConsumeOrderlyStatus.COMMIT;
} else if ((this.consumeTimes.get() % 5) == 0) {
context.setSuspendCurrentQueueTimeMillis(3000);
return ConsumeOrderlyStatus.SUSPEND_CURRENT_QUEUE_A_MOMENT;
}
return ConsumeOrderlyStatus.SUCCESS;
}
});
consumer.start();
System.out.printf("Consumer Started.%n");
}
}
2、Broadcasting 广播消息
什么是Broadcasting
Broadcasting正在向主题的所有订阅者发送消息。如果您希望所有订阅者都收到有关主题的消息，则Broadcasting是一个不错的选择。
Producer example
public class BroadcastProducer {
public static void main(String[] args) throws Exception {
DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");
producer.setNamesrvAddr("192.168.247.132:9876");
producer.start();
for (int i = 0; i < 100; i++){
Message msg = new Message("TopicTest",
"TagA",
"OrderID188",
"Hello world".getBytes(RemotingHelper.DEFAULT_CHARSET));
SendResult sendResult = producer.send(msg);
System.out.printf("%s%n", sendResult);
}
producer.shutdown();
}
}
消费者的例子
public class BroadcastConsumer {
public static void main(String[] args) throws Exception {
DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("example_group_name");
consumer.setNamesrvAddr("192.168.247.132:9876");
consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
//set to broadcast mode
consumer.setMessageModel(MessageModel.BROADCASTING);
consumer.subscribe("TopicTest", "TagA || TagC || TagD");
consumer.registerMessageListener(new MessageListenerConcurrently() {
@Override
public ConsumeConcurrentlyStatus consumeMessage(List msgs,
ConsumeConcurrentlyContext context) {
System.out.printf(Thread.currentThread().getName() + " Receive New Messages: " + msgs + "%n");
return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
}
});
consumer.start();
System.out.printf("Broadcast Consumer Started.%n");
}
}
3、Schedule example 计划消息案例
什么是Schedule信息？
Schedule消息与普通消息的不同之处在于，它们将在指定的时间之后发送。
应用
启动consumer以等待传入的订阅消息
```
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.common.message.MessageExt;
import java.util.List;
public class ScheduledMessageConsumer {
public static void main(String[] args) throws Exception {
// Instantiate message consumer
DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("ExampleConsumer");
consumer.setNamesrvAddr("192.168.247.132:9876");
// Subscribe topics
consumer.subscribe("TestTopic", "*");
// Register message listener
consumer.registerMessageListener(new MessageListenerConcurrently() {
@Override
public ConsumeConcurrentlyStatus consumeMessage(List messages, ConsumeConcurrentlyContext context) {
for (MessageExt message : messages) {
// Print approximate delay time period
System.out.println("Receive message[msgId=" + message.getMsgId() + "] "
+ (System.currentTimeMillis() - message.getStoreTimestamp()) + "ms later");
}
return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
}
});
// Launch consumer
consumer.start();
}
}
```
发送预定的消息
```
import org.apache.rocketmq.client.producer.DefaultMQProducer;
import org.apache.rocketmq.common.message.Message;
public class ScheduledMessageProducer {
public static void main(String[] args) throws Exception {
// Instantiate a producer to send scheduled messages
DefaultMQProducer producer = new DefaultMQProducer("ExampleProducerGroup");
producer.setNamesrvAddr("192.168.247.132:9876");
// Launch producer
producer.start();
int totalMessagesToSend = 100;
for (int i = 0; i < totalMessagesToSend; i++) {
Message message = new Message("TestTopic", ("Hello scheduled message " + i).getBytes());
// This message will be delivered to consumer 10 seconds later.
message.setDelayTimeLevel(3);
// Send the message
producer.send(message);
}
// Shutdown producer after use.
producer.shutdown();
}
}
```
-
验证
您应该看到消息比其存储时间晚10秒消耗。
4、Batch Example 批量消息示例
为何Batch ？
Batch发送消息可提高传递大量短消息的性能。
使用限制
同一批次的消息应该具有：相同的主题，相同的waitStoreMsgOK和没有schedule计划支持。
此外，一批消息的总大小不应超过1MiB。
如何使用批次
如果您一次只发送不超过1MiB的消息集，则很容易使用Batch：
String topic = "BatchTest";
List messages = new ArrayList<>();
messages.add(new Message(topic, "TagA", "OrderID001", "Hello world 0".getBytes()));
messages.add(new Message(topic, "TagA", "OrderID002", "Hello world 1".getBytes()));
messages.add(new Message(topic, "TagA", "OrderID003", "Hello world 2".getBytes()));
try {
producer.send(messages);
} catch (Exception e) {
e.printStackTrace();
//handle the error
}
拆分成列表
只有在发送大批量时，复杂性才会增加，您可能不确定它是否超出了大小限制（1MiB）。
此时，您最好拆分列表：
public class ListSplitter implements Iterator> {
private final int SIZE_LIMIT = 1000 * 1000;
private final List messages;
private int currIndex;
public ListSplitter(List messages) {
this.messages = messages;
}
@Override public boolean hasNext() {
return currIndex < messages.size();
}
@Override public List next() {
int nextIndex = currIndex;
int totalSize = 0;
for (; nextIndex < messages.size(); nextIndex++) {
Message message = messages.get(nextIndex);
int tmpSize = message.getTopic().length() + message.getBody().length;
Map properties = message.getProperties();
for (Map.Entry entry : properties.entrySet()) {
tmpSize += entry.getKey().length() + entry.getValue().length();
}
tmpSize = tmpSize + 20; //for log overhead
if (tmpSize > SIZE_LIMIT) {
//it is unexpected that single message exceeds the SIZE_LIMIT
//here just let it go, otherwise it will block the splitting process
if (nextIndex - currIndex == 0) {
//if the next sublist has no element, add this one and then break, otherwise just break
nextIndex++;
}
break;
}
if (tmpSize + totalSize > SIZE_LIMIT) {
break;
} else {
totalSize += tmpSize;
}
}
List subList = messages.subList(currIndex, nextIndex);
currIndex = nextIndex;
return subList;
}
}
//then you could split the large list into small ones:
ListSplitter splitter = new ListSplitter(messages);
while (splitter.hasNext()) {
try {
List listItem = splitter.next();
producer.send(listItem);
} catch (Exception e) {
e.printStackTrace();
//handle the error
}
}