RocketMQ的消息没消费如何扔回消息队列,请给出java代码实例
时间: 2024-03-13 18:44:29 浏览: 12
可以使用RocketMQ的`MessageExt`对象的`reconsumeTimes`属性来判断消息消费的次数,如果消费次数超过了一定的阈值,就可以将消息重新放回消息队列中。
以下是一个简单的Java代码示例:
```java
import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.common.message.MessageExt;
import org.apache.rocketmq.common.protocol.heartbeat.MessageModel;
import java.util.List;
public class Consumer {
public static void main(String[] args) throws InterruptedException, MQClientException {
DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("example_group");
consumer.setNamesrvAddr("127.0.0.1:9876");
consumer.subscribe("example_topic", "*");
consumer.setMessageModel(MessageModel.CLUSTERING);
consumer.registerMessageListener(new MessageListenerConcurrently() {
@Override
public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) {
for (MessageExt msg : msgs) {
System.out.printf("Consume message: %s%n", new String(msg.getBody()));
if (msg.getReconsumeTimes() >= 3) {
// 如果消息消费次数超过3次,则将消息重新放回队列中
return ConsumeConcurrentlyStatus.RECONSUME_LATER;
}
}
return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
}
});
consumer.start();
System.out.println("Consumer started.");
}
}
```
在上述代码中,如果消息的消费次数超过了3次,则会将消息重新放回到消息队列中,等待下一次消费。