[I] RocketMQ监听者收到消息后发送到其他Topic时报空指针异常 [rocketmq-spring]

Thu, 22 Feb 2024 06:08:29 -0800 


lilinjiang opened a new issue, #632:
URL: https://github.com/apache/rocketmq-spring/issues/632

   报错日志：
   java.lang.NullPointerException: null
        at 
org.apache.rocketmq.spring.core.RocketMQTemplate.syncSend(RocketMQTemplate.java:708)
   
   问题原因：
   经过排查源码发现 
监听者准备完成的时机早于生产者准备完成。导致项目启动时监听者监听到消息后立即通过@ExtRocketMQTemplateConfiguration注解扩展的RocketMQTemplate发送消息产生空指针，因为此时RocketMQTemplate的producer（实际的生产者）属性等于null
   
   监听者是基于BeanPostProcessor 的 postProcessAfterInitialization 方法实现启动监听
   
   生产者是基于SmartInitializingSingleton的afterSingletonsInstantiated 
方法实现设置真正的生产者（晚于监听者准备好）
   
   <img width="1217" alt="监听者图片" 
src="https://github.com/apache/rocketmq-spring/assets/36615541/b097d0aa-9ab2-4683-a27e-ddfc077f10db";>
   
   <img width="1155" alt="生产者图片" 
src="https://github.com/apache/rocketmq-spring/assets/36615541/c23e8186-5c2c-46b1-982d-8480667116c3";>
   
   解决办法：
   
   ListenerContainerConfiguration 新增
    private final List<DefaultRocketMQListenerContainer> containers = new 
ArrayList<>();
    并修改以下代码
   <img width="1098" alt="Snipaste_2024-02-22_22-05-43" 
src="https://github.com/apache/rocketmq-spring/assets/36615541/fa3e4fc4-7ab0-4d96-87a4-adaef53d55fe";>
   RocketMQMessageListenerBeanPostProcessor 增加实现 SmartLifecycle
   并修改以下代码
   
![1708610869203](https://github.com/apache/rocketmq-spring/assets/36615541/feec3994-9004-4b69-abe3-eeecbc2c5806)
   
   
   


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