RocketMQ5.1.0消费者监听注解

在RocketMQ 5.1.0版本中，除了使用监听器类来处理消息外，还可以使用注解来标注消息处理方法。具体步骤如下：

1. 添加`@RocketMQMessageListener`注解到消费者类上，指定`consumerGroup`、`topic`和`messageModel`等属性。

2. 在消息处理方法上添加`@RocketMQMessageListener`注解，指定`consumerGroup`、`topic`、`messageModel`和`selectorExpression`等属性。

3. 在消息处理方法的参数中添加`List<MessageExt>`类型的参数，用于接收从broker拉取回来的消息。

下面是一个使用注解的示例：

import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import org.apache.rocketmq.client.consumer.rebalance.AllocateMessageQueueAveragely;
import org.apache.rocketmq.client.consumer.rebalance.AllocateMessageQueueByConfig;
import org.apache.rocketmq.common.message.MessageExt;
import org.springframework.stereotype.Service;

import java.util.List;

import com.alibaba.rocketmq.annotation.ConsumeMode;
import com.alibaba.rocketmq.annotation.MessageModel;
import com.alibaba.rocketmq.annotation.RocketMQMessageListener;
import com.alibaba.rocketmq.common.consumer.ConsumeFromWhere;

@Service
@RocketMQMessageListener(consumerGroup = "test-group", topic = "test-topic", selectorExpression = "test-tag", 
    messageModel = MessageModel.CLUSTERING, consumeMode = ConsumeMode.CONCURRENTLY, consumeThreadMax = 64,
    consumeThreadMin = 20, messageQueueListener = AllocateMessageQueueAveragely.class, consumeFromWhere = ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET)
public class MyMessageListener implements MessageListenerConcurrently {

    @Override
    @RocketMQMessageListener(consumerGroup = "test-group", topic = "test-topic", selectorExpression = "test-tag",
        messageModel = MessageModel.CLUSTERING, consumeMode = ConsumeMode.CONCURRENTLY)
    public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) {
        for (MessageExt msg : msgs) {
            System.out.printf("%s Receive New Messages: %s %n", Thread.currentThread().getName(), msg);
        }
        return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
    }
}

在这个示例中，我们使用了`@RocketMQMessageListener`注解来标注消费者类和消息处理方法。我们指定了消费者组、主题、标签、消息模式、消费模式、消费线程数量、队列分配策略、消费起始位置等属性。在消息处理方法中，我们使用了`ConsumeConcurrentlyContext`参数和`List<MessageExt>`参数来接收消息，并打印了收到的消息。最后，我们返回了`ConsumeConcurrentlyStatus.CONSUME_SUCCESS`实例，表示这个消息已经被成功消费。