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：