只捕捉不到ChuckNorrisException

是否有可能在Java中构造一段代码，使假设的Java .lang. chucknorrisexception无法捕获?

我想到的是使用拦截器或面向方面的编程。

当前回答

实际上，公认的答案并不是那么好，因为Java需要在没有验证的情况下运行，即代码在正常情况下无法工作。

AspectJ拯救了真正的解决方案!

异常类:

package de.scrum_master.app;

public class ChuckNorrisException extends RuntimeException {
    public ChuckNorrisException(String message) {
        super(message);
    }
}

方面:

package de.scrum_master.aspect;

import de.scrum_master.app.ChuckNorrisException;

public aspect ChuckNorrisAspect {
    before(ChuckNorrisException chuck) : handler(*) && args(chuck) {
        System.out.println("Somebody is trying to catch Chuck Norris - LOL!");
        throw chuck;
    }
}

示例应用程序:

package de.scrum_master.app;

public class Application {
    public static void main(String[] args) {
        catchAllMethod();
    }

    private static void catchAllMethod() {
        try {
            exceptionThrowingMethod();
        }
        catch (Throwable t) {
            System.out.println("Gotcha, " + t.getClass().getSimpleName() + "!");
        }
    }

    private static void exceptionThrowingMethod() {
        throw new ChuckNorrisException("Catch me if you can!");
    }
}

输出:

Somebody is trying to catch Chuck Norris - LOL!
Exception in thread "main" de.scrum_master.app.ChuckNorrisException: Catch me if you can!
    at de.scrum_master.app.Application.exceptionThrowingMethod(Application.java:18)
    at de.scrum_master.app.Application.catchAllMethod(Application.java:10)
    at de.scrum_master.app.Application.main(Application.java:5)

2014-04-19 10:42:44

其他回答

Two fundamental problems with exception handling in Java are that it uses the type of an exception to indicate whether action should be taken based upon it, and that anything which takes action based upon an exception (i.e. "catch"es it) is presumed to resolve the underlying condition. It would be useful to have a means by which an exception object could decide which handlers should execute, and whether the handlers that have executed so far have cleaned things up enough for the present method to satisfy its exit conditions. While this could be used to make "uncatchable" exceptions, two bigger uses would be to (1) make exceptions which will only be considered handled when they're caught by code that actually knows how to deal with them, and (2) allow for sensible handling of exceptions which occur in a finally block (if a FooException during a finally block during the unwinding of a BarException, both exceptions should propagate up the call stack; both should be catchable, but unwinding should continue until both have been caught). Unfortunately, I don't think there would be any way to make existing exception-handling code work that way without breaking things.

2012-12-15 23:53:16

我的答案是基于@jtahlborn的想法，但它是一个完全可用的Java程序，可以打包到JAR文件中，甚至可以作为web应用程序的一部分部署到您最喜欢的应用服务器上。

首先，让我们定义ChuckNorrisException类，这样它就不会从一开始就崩溃JVM(顺便说一句，Chuck真的很喜欢崩溃JVM:)

package chuck;

import java.io.PrintStream;
import java.io.PrintWriter;

public class ChuckNorrisException extends Exception {

    public ChuckNorrisException() {
    }

    @Override
    public Throwable getCause() {
        return null;
    }

    @Override
    public String getMessage() {
        return toString();
    }

    @Override
    public void printStackTrace(PrintWriter s) {
        super.printStackTrace(s);
    }

    @Override
    public void printStackTrace(PrintStream s) {
        super.printStackTrace(s);
    }
}

现在让敢死队来构建它:

package chuck;

import javassist.*;

public class Expendables {

    private static Class clz;

    public static ChuckNorrisException getChuck() {
        try {
            if (clz == null) {
                ClassPool pool = ClassPool.getDefault();
                CtClass cc = pool.get("chuck.ChuckNorrisException");
                cc.setSuperclass(pool.get("java.lang.Object"));
                clz = cc.toClass();
            }
            return (ChuckNorrisException)clz.newInstance();
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }
}

最后是Main类:

package chuck;

public class Main {

    public void roundhouseKick() throws Exception {
        throw Expendables.getChuck();
    }

    public void foo() {
        try {
            roundhouseKick();
        } catch (Throwable ex) {
            System.out.println("Caught " + ex.toString());
        }
    }

    public static void main(String[] args) {
        try {
            System.out.println("before");
            new Main().foo();
            System.out.println("after");
        } finally {
            System.out.println("finally");
        }
    }
}

使用以下命令编译并运行它:

java -Xverify:none -cp .:<path_to_javassist-3.9.0.GA.jar> chuck.Main

您将得到以下输出:

before
finally

这并不奇怪，毕竟这是一个回旋踢:)

2012-12-18 22:56:28

在finalize中调用System.exit(1)，并抛出来自所有其他方法的异常副本，以便程序退出。

2014-04-18 01:23:38

你可以把ChuckNorris隐藏起来，也可以把他封装起来，也可以把他吞下去……

try {doChuckAction();} catch(ChuckNorrisException cne){/*做其他事情*/}

2012-12-15 04:39:23