jdk中动态代理异常处理分析：UndeclaredThrowableException

// 接口定义
public interface IService {
 void foo() throws SQLException;
}
public class ServiceImpl implements IService{
 @Override
 public void foo() throws SQLException {
  throw new SQLException("I test throw an checked Exception");
 }
}
// 动态代理
public class IServiceProxy implements InvocationHandler {
 private Object target;

 IServiceProxy(Object target){
  this.target = target;
 }

 @Override
 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
  return method.invoke(target, args);
 }
}

public class MainTest {
 public static void main(String[] args) {
  IService service = new ServiceImpl();
  IService serviceProxy = (IService) Proxy.newProxyInstance(service.getClass().getClassLoader(),
    service.getClass().getInterfaces(), new IServiceProxy(service));
  try {
   serviceProxy.foo();
  } catch (Exception e){
   e.printStackTrace();
  }
 }
}

java.lang.reflect.UndeclaredThrowableException
 at com.sun.proxy.$Proxy0.foo(Unknown Source)
 at com.learn.reflect.MainTest.main(MainTest.java:16)
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.learn.reflect.IServiceProxy.invoke(IServiceProxy.java:19)
 ... 2 more
Caused by: java.sql.SQLException: I test throw an checked Exception
 at com.learn.reflect.ServiceImpl.foo(ServiceImpl.java:11)
 ... 7 more

java.sql.SQLException: I test throw an checked Exception
 at com.learn.reflect.ServiceImpl.foo(ServiceImpl.java:11)
 ...

public final class IServiceProxy$1 extends Proxy implements IService {
 private static Method m1;
 private static Method m2;
 private static Method m3;
 private static Method m0;

 public IServiceProxy$1(InvocationHandler var1) throws {
  super(var1);
 }
 
 public final void foo() throws SQLException {
  try {
   super.h.invoke(this, m3, (Object[])null);
  } catch (RuntimeException | SQLException | Error var2) {
   throw var2;
  } catch (Throwable var3) {
   throw new UndeclaredThrowableException(var3);
  }
 }
 static {
  try {
   m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[]{Class.forName("java.lang.Object")});
   m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
   m3 = Class.forName("com.learn.reflect.IService").getMethod("foo", new Class[0]);
   m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
  } catch (NoSuchMethodException var2) {
   throw new NoSuchMethodError(var2.getMessage());
  } catch (ClassNotFoundException var3) {
   throw new NoClassDefFoundError(var3.getMessage());
  }
 }
}

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