JAVA高级面试进阶训练营视频教程

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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：