java 重新抛出 InvocationTargetException 目标异常
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Re-throw an InvocationTargetException target exception
提问by Vincent Catalano
How does one re-throw the target exception of an InvocationTargetException. I have a method which uses reflection to call the invoke() method within one of my classes. However, if there is an Exception thrown within my code, I am not concerned about the InvocationTargetException and only want the target exception. Here is an example:
如何重新抛出 InvocationTargetException 的目标异常。我有一个方法，它使用反射在我的一个类中调用 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。下面是一个例子：
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
}
}
The primary problem I am facing is that calling throw e.getCause(); doesn't throw an Exception but rather throws a Throwable. Perhaps I am approaching this incorrectly?
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。也许我不正确地接近这个？
回答by JB Nizet
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.
}
}
回答by Tim Bender
Exception#getCausereturns a Throwable. If you want the compiler to think you are throwing an Exceptionthen you probably need to cast it.
Exception#getCause返回一个Throwable. 如果您希望编译器认为您正在抛出一个，Exception那么您可能需要对其进行转换。
throw (Exception) e.getCause();
回答by emory
The below is verbose, but I like to avoid reflection and casting. I don't think (but am not sure) that Java 7's multi catch syntax would be useful.
下面是冗长的，但我喜欢避免反射和投射。我不认为（但不确定）Java 7 的多捕获语法会有用。
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" ;
}
}
}
回答by Stephan
You can rethrow any exception you caught before by using the throw keyword and the corresponding object you caught:
您可以使用 throw 关键字和您捕获的相应对象重新抛出您之前捕获的任何异常：
catch (XXXException e)
{
throw e;
}
回答by Peter Lawrey
You can rethrow the cause without declaring it explicitly.
您可以在不明确声明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());
}
}
