Question

如何重新抛出InvocationTargetException的目标异常。我有一个方法，它使用反射来调用我的一个类中的invoke（）方法。但是，如果在我的代码中抛出异常，我不关心InvocationTargetException并且只想要目标异常。这是一个例子：

public static Object executeViewComponent(String name, Component c,
        HttpServletRequest request) throws Exception {

    try {
        return c.getClass()
                .getMethod(c.getMetaData().getMethod(), HttpServletRequest.class)
                .invoke(c, request);
    } catch (InvocationTargetException e) {
        // throw the target exception here
    }
}

我面临的主要问题是调用throw e.getCause（）;不会抛出异常而是抛出一个Throwable。也许我接近这个错误？

Answer 1

catch (InvocationTargetException e) {
    if (e.getCause() instanceof Exception) {
        throw (Exception) e.getCause();
    }
    else {
        // decide what you want to do. The cause is probably an error, or it's null.
    }
}

Answer 2

Exception#getCause返回Throwable。如果您希望编译器认为您正在抛出Exception，那么您可能需要进行强制转换。

throw (Exception) e.getCause();

Answer 3

以下是冗长的，但我喜欢避免反思和投射。我不认为（但不确定）Java 7的多捕获语法会很有用。

public static Object executeViewComponent(String name, Component c,
        HttpServletRequest request) throw KnownException_1 , KnownException_2 , ... , KnownException_n {

    try {
        return c.getClass()
                .getMethod(c.getMetaData().getMethod(), HttpServletRequest.class)
                .invoke(c, request);
    }
    catch ( InvocationTargetException cause )
    {
          assert cause . getCause ( ) != null : "Null Cause" ;
          try
          {
               throw cause . getCause ( ) ;
          }
          catch ( KnownException_1 c )
          {
                throw c
          }
          catch ( KnownException_2 c )
          {
                throw c
          }
          ...
          catch ( KnownException_n c )
          {
                throw c
          }
          catch ( RuntimeException c )
          {
                throw c ;
          }
          catch ( Error c )
          {
                throw c ;
          }
          catch ( Throwable c )
          {
                assert false : "Unknown Cause" ;
          }
    }
}

Answer 4

您可以使用throw关键字和捕获的相应对象重新抛出之前捕获的任何异常：

catch (XXXException e)
{
       throw e;
}

Answer 5

您可以在不明确声明原因的情况下重新抛出原因。

public static Object executeViewComponent(String name, Component c,
        HttpServletRequest request) throw /* known exceptions */ {

    try {
        return c.getClass()
                .getMethod(c.getMetaData().getMethod(), HttpServletRequest.class)
                .invoke(c, request);
    } catch (InvocationTargetException e) {
        // rethrow any exception.
        Thread.currentThread().stop(e.getCause());
    }
}

重新抛出InvocationTargetException目标异常

5 个答案: