[GitHub] [dubbo] cheese8 commented on issue #10257: 启动时报java.lang.UnsupportedOperationException导致无法运行

[GitBox <gi...@apache.org>]

cheese8 commented on issue #10257:
URL: https://github.com/apache/dubbo/issues/10257#issuecomment-1173049846

   > 问题的根源在于org.apache.dubbo.config.spring.util.DubboAnnotationUtils类中的public static Map<String, String> convertParameters(String[] parameters)中的差异，在3.0.6及之前版本ArrayUtils.isEmpty(parameters)为空时直接返回的是null，在3.0.7开始的版本返回的是Collections.emptyMap();
   > 
   > 当dubbo的服务bean的定义时用到了这个方法，见org.apache.dubbo.config.spring.beans.factory.annotation.ServiceAnnotationPostProcessor类的buildServiceBeanDefinition方法 <img alt="Pasted Graphic 4" width="1428" src="https://user-images.githubusercontent.com/421994/177032573-65d2ec96-3d66-478a-8feb-91e5654b263b.png">
   > 
   > 在程序运行时refresh会调用到org.apache.dubbo.config.AbstractConfig的assignProperties方法，此方法又会调用到invokeSetParameters方法，在invokeSetParameters方法中又会调用private static Map<String, String> invokeGetParameters(Class c, Object o)方法，此方法里面有一个method的反射调用，其实最终调用到org.apache.dubbo.config.AbstractMethodConfig的getParameters方法，那么就要看setParameters是何时调用的了， <img alt="image" width="1250" src="https://user-images.githubusercontent.com/421994/177033265-4a26a988-29e3-4fe0-b803-9c0e9c621297.png"> <img alt="image" width="1430" src="https://user-images.githubusercontent.com/421994/177033298-d63e6079-a11d-4f58-b6ba-6e0e5538debb.png"> 通过追踪也就知道问题的症结就在于bean定义时赋值的Collections.emptyMap();导致的。
   > 
   > 因此建议综合考虑org.apache.dubbo.config.spring.util.DubboAnnotationUtils.convertParameters的差异性
   
   返回emptyMap比null好。


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