java主线程捕获子线程中的异常

柔光的暖阳◎ 2022-05-20 23:04 320阅读 0赞

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

执行结果如下：

![70][]

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：

![70 1][]

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：

![70 2][]

[70]: /images/20220521/63e297c2086840d6bbd28fdce1b12f4b.png
[70 1]: /images/20220521/69db13966e41448695cc6c3e5688e39c.png
[70 2]: /images/20220521/5b27a98af8ae4413a414af74ba2479f5.png