例外顺序

Question

我有一个抛出 MalformedURLException 的方法。我用 try-catch.
捕获了异常但是它没有捕获 MalformedURLException，而是跳转到 EJBException.

try {
    myMethod(); // throws an exception
} catch (WebApplicationException ex) {
    ex.printStackTrace();
} catch (MalformedURLException ex) {
    ex.printStackTrace(); // I expected the debugger to jump to that line
} catch (EJBException ex) {
    ex.printStackTrace(); // debugger jumps to this line
} catch (Exception ex) {
    ex.printStackTrace();
}

堆栈跟踪：

WARNING:   A system exception occurred during an invocation on EJB MyClass, method: public com.name.AnotherClass com.name.MyClass.myMethod(java.lang.String,java.lang.String) throws java.net.MalformedURLException
WARNING:   javax.ejb.EJBException
    [...] // much more text...
Caused by: javax.ws.rs.WebApplicationException: HTTP 400 Bad Request
    [...] // much more text...
FATAL:   javax.ejb.EJBException
    [...] // much more text...
Caused by: javax.ws.rs.WebApplicationException: HTTP 400 Bad Request
    [...] // much more text...

如stated here:

If the first catch matches the exception, it executes, if it doesn't, the next one is tried and on and on until one is matched or none are.

在我的示例中，MalformedURLException 首先触发，如您在第一行中所见：

throws java.net.MalformedURLException

只有第二行说：

javax.ejb.EJBException

那么，如果 MalformedURLException 先触发，为什么它会立即跳转到 EJBException？

Answer 1

检查 EJBException 的 ex.getCause()。 MalformedURLException 由 EJB 容器的魔法包装。

人们可能会想象某个地方

try { ...
} catch (Exception ex) {
    throw new EJBException(ex); // Cause: ex.
}

例外顺序

Order of Exceptions

java

exception-handling

exception

try-catch