RocketMQ（二）
RocketMQ
Pom
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<dependencies> <dependency> <groupId>com.alibaba.rocketmq</groupId> <artifactId>rocketmq-client</artifactId> <version>3.0.10</version> </dependency> <dependency> <groupId>com.alibaba.rocketmq</groupId> <artifactId>rocketmq-all</artifactId> <version>3.0.10</version> <type>pom</type> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.1.1</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-core</artifactId> <version>1.1.1</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.10</version> <scope>test</scope> </dependency> </dependencies> |
生产者
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publicclass Producer {
publicstaticvoid main(String[] args) throws MQClientException { DefaultMQProducer producer = new DefaultMQProducer("rmq-group"); producer.setNamesrvAddr("192.168.110.195:9876;192.168.110.199:9876"); producer.setInstanceName("producer"); producer.start(); try { for (inti = 0; i < 10; i++) { Thread.sleep(1000); // 每秒发送一次MQ Message msg = new Message("itmayiedu-topic", // topic 主题名称 "TagA", // tag 临时值 ("itmayiedu-"+i).getBytes()// body 内容 ); SendResult sendResult = producer.send(msg); System.out.println(sendResult.toString()); } } catch (Exception e) { e.printStackTrace(); } producer.shutdown(); }
} |
消费者
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publicclass Consumer { publicstaticvoid main(String[] args) throws MQClientException { DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("rmq-group");
consumer.setNamesrvAddr("192.168.110.195:9876;192.168.110.199:9876"); consumer.setInstanceName("consumer"); consumer.subscribe("itmayiedu-topic", "TagA");
consumer.registerMessageListener(new MessageListenerConcurrently() { @Override public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) { for (MessageExt msg : msgs) { System.out.println(msg.getMsgId()+"---"+new String(msg.getBody())); } return ConsumeConcurrentlyStatus.CONSUME_SUCCESS; } }); consumer.start(); System.out.println("Consumer Started."); } } |
RocketMQ重试机制
MQ 消费者的消费逻辑失败时，可以通过设置返回状态达到消息重试的结果。
MQ 消息重试只针对集群消费方式生效；广播方式不提供失败重试特性，即消费失败后，失败消息不再重试，继续消费新的消息。
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publicclass Consumer { publicstaticvoid main(String[] args) throws MQClientException { DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("rmq-group");
consumer.setNamesrvAddr("192.168.110.195:9876;192.168.110.199:9876"); consumer.setInstanceName("consumer"); consumer.subscribe("itmayiedu-topic", "TagA");
consumer.registerMessageListener(new MessageListenerConcurrently() { @Override public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) { for (MessageExt msg : msgs) { System.out.println(msg.getMsgId() + "---" + new String(msg.getBody())); } try { inti = 1 / 0; } catch (Exception e) { e.printStackTrace(); // 需要重试 return ConsumeConcurrentlyStatus.RECONSUME_LATER;
} // 不需要重试 return ConsumeConcurrentlyStatus.CONSUME_SUCCESS; } }); consumer.start(); System.out.println("Consumer Started."); } } |
注意:每次重试后，消息ID都不一致，所以不能使用消息ID判断幂等。
RocketMQ如何解决消息幂等
注意:每次重试后，消息ID都不一致，所以不能使用消息ID判断幂等。
解决办法:使用自定义全局ID判断幂等，例如流水ID、订单号
使用msg.setKeys 进行区分
生产者:
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publicclass Producer {
publicstaticvoid main(String[] args) throws MQClientException { DefaultMQProducer producer = new DefaultMQProducer("rmq-group"); producer.setNamesrvAddr("192.168.110.195:9876;192.168.110.199:9876"); producer.setInstanceName("producer"); producer.start(); try { for (inti = 0; i < 1; i++) { Thread.sleep(1000); // 每秒发送一次MQ Message msg = new Message("itmayiedu-topic", // topic 主题名称 "TagA", // tag 临时值 ("itmayiedu-6" + i).getBytes()// body 内容 ); msg.setKeys(System.currentTimeMillis() + ""); SendResult sendResult = producer.send(msg); System.out.println(sendResult.toString()); } } catch (Exception e) { e.printStackTrace(); } producer.shutdown(); }
} |
消费者:
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staticprivate Map<String, String> logMap = new HashMap<>();
publicstaticvoid main(String[] args) throws MQClientException { DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("rmq-group");
consumer.setNamesrvAddr("192.168.110.195:9876;192.168.110.199:9876"); consumer.setInstanceName("consumer"); consumer.subscribe("itmayiedu-topic", "TagA");
consumer.registerMessageListener(new MessageListenerConcurrently() { @Override public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) { String key = null; String msgId = null; try { for (MessageExt msg : msgs) { key = msg.getKeys(); if (logMap.containsKey(key)) { // 无需继续重试。 System.out.println("key:"+key+",无需重试..."); return ConsumeConcurrentlyStatus.CONSUME_SUCCESS; } msgId = msg.getMsgId(); System.out.println("key:" + key + ",msgid:" + msgId + "---" + new String(msg.getBody())); inti = 1 / 0; }
} catch (Exception e) { e.printStackTrace(); return ConsumeConcurrentlyStatus.RECONSUME_LATER; } finally { logMap.put(key, msgId); } return ConsumeConcurrentlyStatus.CONSUME_SUCCESS; } }); consumer.start(); System.out.println("Consumer Started."); } |
