java主线程捕获子线程中的异常

本文主要参考：《think in java》

好，下面上货。

正常情况下，如果不做特殊的处理，在主线程中是不能够捕获到子线程中的异常的。

例如下面的情况。

package com.xueyou.demo.theadexceptiondemo;















public class ThreadExceptionRunner implements Runnable{







    @Override







    public void run() {







        throw new RuntimeException("error !!!!");







    }







}

使用线程执行上面的任务

package com.xueyou.demo.theadexceptiondemo;















import com.sun.glass.ui.TouchInputSupport;















import java.util.concurrent.ExecutorService;







import java.util.concurrent.Executors;







import java.util.concurrent.ThreadFactory;















public class ThreadExceptionDemo {







    public static void main(String[] args) {







        try {







            Thread thread = new Thread(new ThreadExceptionRunner());







            thread.start();







        } catch (Exception e) {







            System.out.println("========");







            e.printStackTrace();







        } finally {







        }







        System.out.println(123);







    }







}

执行结果如下：

如果想要在主线程中捕获子线程的异常，我们需要使用ExecutorService，同时做一些修改。

如下：

package com.xueyou.demo.theadexceptiondemo;















import com.sun.glass.ui.TouchInputSupport;















import java.util.concurrent.ExecutorService;







import java.util.concurrent.Executors;







import java.util.concurrent.ThreadFactory;















public class ThreadExceptionDemo {







    public static void main(String[] args) {







        try {







            Thread thread = new Thread(new ThreadExceptionRunner());







            thread.start();







        } catch (Exception e) {







            System.out.println("========");







            e.printStackTrace();







        } finally {







        }







        System.out.println(123);







        ExecutorService exec = Executors.newCachedThreadPool(new HandleThreadFactory());







        exec.execute(new ThreadExceptionRunner());







        exec.shutdown();







    }







}















class MyUncaughtExceptionHandle implements Thread.UncaughtExceptionHandler {







    @Override







    public void uncaughtException(Thread t, Throwable e) {







        System.out.println("caught " + e);







    }







}















class HandleThreadFactory implements ThreadFactory {







    @Override







    public Thread newThread(Runnable r) {







        System.out.println("create thread t");







        Thread t = new Thread(r);







        System.out.println("set uncaughtException for t");







        t.setUncaughtExceptionHandler(new MyUncaughtExceptionHandle());







        return t;







    }















}

这样就能够捕获到异常了，运行结果如下：

上面的方式是设置每一个线程执行时候的异常处理。如果每一个线程的异常处理相同，我们可以用如下的方式进行处理，使用Thread的静态方法。

Thread.setDefaultUncaughtExceptionHandler(new MyUncaughtExceptionHandle());

整体代码如下：

package com.xueyou.demo.theadexceptiondemo;















import com.sun.glass.ui.TouchInputSupport;















import java.util.concurrent.ExecutorService;







import java.util.concurrent.Executors;







import java.util.concurrent.ThreadFactory;















/**







 * Created by wuxueyou on 2018/6/24.







 */







public class ThreadExceptionDemo {







    public static void main(String[] args) {







        try {







            Thread thread = new Thread(new ThreadExceptionRunner());







            thread.start();







        } catch (Exception e) {







            System.out.println("========");







            e.printStackTrace();







        } finally {







        }







        System.out.println(123);







        Thread.setDefaultUncaughtExceptionHandler(new MyUncaughtExceptionHandle());







//        ExecutorService exec = Executors.newCachedThreadPool(new HandleThreadFactory());







        ExecutorService exec = Executors.newCachedThreadPool();







        exec.execute(new ThreadExceptionRunner());







        exec.shutdown();















    }







}

运行结果：