consumer always catch java.lang.reflect.UndeclaredThrowableException for the exception thrown from provider

[eachcan]

• I have searched the issues of this repository and believe that this is not a duplicate.
• I have checked the FAQ of this repository and believe that this is not a duplicate. (This page is missing)

Environment

• Dubbo version: 2.7.1-SNAPSHOT
• Operating System version: MacOSX 10.14.1
• Java version: 1.8.0_191

Steps to reproduce this issue

1. Define exception class and other rpc classes
   定义异常类和其他 RPC 相关类

API Defination

public class ValidationException extends RuntimeException {
    public ValidationException(String message) {
        super(message);
    }
}

public interface MailService {
    MailResponse send(MailRequest request);
}

@Data
public class MailRequest implements Serializable {
    /**
     * 收件人邮箱地址
     */
    @NotBlank(message = "收件人不能为空")
    @Email(message = "收件人只能是一个 Email 地址")
    private String to;
}

@Data
public class MailResponse implements Serializable {
    /** 是否成功*/
    private boolean success = true;
}

Provider

@Service(version = "${service.version}",protocol = "${dubbo.protocol.id}",application = "${dubbo.application.name}",registry = "${dubbo.registry.id}",executes = 32)
public class MailServiceImpl implements MailService {
    // ...

    @Override
    public ServerResponse send(MailRequest request) {
        Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
        Set<ConstraintViolation<MailRequest>> vset = validator.validate(request);
        if (!vset.isEmpty()) {
            throw new ValidationException(vset.iterator().next().getMessage());
        }
        return new MailResponse();
    }
}

Consumer

            try {
                MailResponse response = mailService.send(request);
                System.out.println(response.isSuccess());
            } catch (Exception e) {
                e.printStackTrace();
            }

Expected Result

此处应当可捕获 ValidationException

Expect ValidationException to be caught.

Actual Result

但是我们捕获到了 UndeclaredThrowableException

java.lang.reflect.UndeclaredThrowableException
	at com.sun.proxy.$Proxy36.send(Unknown Source)
	at test.....MailRunner.lambda$runner$0(MailRunner.java:38)
	at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:804)
	at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:794)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:324)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
	at test.....MailRunner.main(MailRunner.java:54)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.alibaba.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor$ReferenceBeanInvocationHandler.invoke(ReferenceAnnotationBeanPostProcessor.java:159)
	... 8 more
Caused by: ....ValidationException: may not be empty
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.googlecode.jsonrpc4j.DefaultExceptionResolver.createThrowable(DefaultExceptionResolver.java:162)
	at com.googlecode.jsonrpc4j.DefaultExceptionResolver.resolveException(DefaultExceptionResolver.java:82)
	at com.googlecode.jsonrpc4j.JsonRpcClient.readResponse(JsonRpcClient.java:345)
	at com.googlecode.jsonrpc4j.JsonRpcClient.readResponse(JsonRpcClient.java:285)
	at com.googlecode.jsonrpc4j.JsonRpcHttpClient.invoke(JsonRpcHttpClient.java:161)
	at com.googlecode.jsonrpc4j.spring.JsonProxyFactoryBean.invoke(JsonProxyFactoryBean.java:136)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
	at com.sun.proxy.$Proxy35.send(Unknown Source)
	at com.alibaba.dubbo.common.bytecode.Wrapper0.invokeMethod(Wrapper0.java)
	at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:47)
	at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:76)
	at com.alibaba.dubbo.rpc.protocol.AbstractProxyProtocol$2.doInvoke(AbstractProxyProtocol.java:97)
	at com.alibaba.dubbo.rpc.protocol.AbstractInvoker.invoke(AbstractInvoker.java:155)
	at com.alibaba.dubbo.rpc.listener.ListenerInvokerWrapper.invoke(ListenerInvokerWrapper.java:77)
	at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:62)
	at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
	at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75)
	at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
	at com.alibaba.dubbo.rpc.protocol.dubbo.filter.FutureFilter.invoke(FutureFilter.java:54)
	at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
	at com.alibaba.dubbo.rpc.filter.ConsumerContextFilter.invoke(ConsumerContextFilter.java:49)
	at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)
	at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:56)
	at com.alibaba.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:78)
	at com.alibaba.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:244)
	at com.alibaba.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:75)
	at com.alibaba.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:52)
	at com.alibaba.dubbo.common.bytecode.proxy0.send(proxy0.java)
	... 13 more

[lqclester]

遇到相同的问题，现在只能写filter在consumer自行转换

[scm1219]

原因是服务端抛出的异常被java的反射捕获，包装成了InvocationTargetException
然后客户端代理处理异常，发现InvocationTargetException不在接口声明的异常中，就再包装成
UndeclaredThrowableException了

比对了2.6.4和2.6.5，几乎就是重写了ReferenceAnnotationBeanPostProcessor。
评估后发现写转换工程太大了，最终决定修改ReferenceBeanInvocationHandler的invoke代码

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            try{
                 return method.invoke(bean, args);
            }catch(InvocationTargetException ite){
                 throw ite.getTargetException();
            }
        }

临时发布一个patch到本地maven仓中使用，期望未来修复吧

[mercyblitz]

2.6.6 will be resolved, please refer the commit.

[eachcan]

@mercyblitz 2.6.6 has been merged into 2.7.0, but this issue is still there.

Should I push a new commit?

[jingege]

Apache dubbo 2.7.0 has the same issue.

[ikcro]

apache dubbo2.7.0 I've tried it and it still doesn't work