InvocationTargetException与UndeclaredThrowableException

InvocationTargetException

当java反射调用方抛出异常时，就会用InvocationTargetException将原异常包裹；

UndeclaredThrowableException

java动态代理时抛出的异常。当对某接口进行动态代理，接口的方法名称上未声明某类受检异常，而方法却抛出了该异常，动态代理会将该异常用UndeclaredThrowableException包裹。

由于jdk动态代理内部会调用method.invoke进行调用，当method抛出异常时，则会抛出InvocationTargetException。

由于InvocationTargetException是受检异常，当代理接口方法未标识InvocationTargetException，则抛出UndeclaredThrowableException

处理方法：

public static Throwable unwrapThrowable(Throwable wrapped) {
    Throwable unwrapped = wrapped;
    while (true) {
        if (unwrapped instanceof InvocationTargetException) {
            unwrapped = ((InvocationTargetException) unwrapped).getTargetException();
        } else if (unwrapped instanceof UndeclaredThrowableException) {
            unwrapped = ((UndeclaredThrowableException) unwrapped).getUndeclaredThrowable();
        } else {
            return unwrapped;
        }
    }
}