InvocationTargetException與UndeclaredThrowableException

InvocationTargetException

當java反射調用方拋出異常時，就會用InvocationTargetException將原異常包裹；

UndeclaredThrowableException

java動態代理時拋出的異常。當對某接口進行動態代理，接口的方法名稱上未聲明某類受檢異常，而方法卻拋出了該異常，動態代理會將該異常用UndeclaredThrowableException包裹。

由於jdk動態代理內部會調用method.invoke進行調用，當method拋出異常時，則會拋出InvocationTargetException。

由於InvocationTargetException是受檢異常，當代理接口方法未標識InvocationTargetException，則拋出UndeclaredThrowableException

處理方法：

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;
        }
    }
}