JAVA并发，线程异常捕获

由于线程的特性，当我们启动了线程是没有办法用try catch捕获异常的，如下例：

 package com.xt.thinks21_2;

 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;

 /**
  * 线程异常捕获测试
  *
  * @author xue
  *
  */
 public class ThreadUncaughtExceptionTest implements Runnable {

     @Override
     public void run() {
         // TODO Auto-generated method stub
         throw new NullPointerException();
     }

     public static void main(String[] args) {
         try {
             ExecutorService es = Executors.newCachedThreadPool();
             es.execute(new ThreadUncaughtExceptionTest());
             es.shutdown();
             // or this
             // Thread t = new Thread(new ThreadUncaughtExceptionTest());
             // t.start();
         } catch (Exception e) {
             // TODO: handle exception
         }

     }
 }

打印异常信息为：

Exception in thread "pool-1-thread-1" java.lang.NullPointerException
at com.xt.thinks21_2.ThreadUncaughtExceptionTest.run(ThreadUncaughtExceptionTest.java:17)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

此时，我们需要为线程定制工厂类来生产线程，为线程指定UncaughtExceptionHandler

 package com.xt.thinks21_2;

 import java.lang.Thread.UncaughtExceptionHandler;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;

 /**
  * 未捕获异常执行程序
  *
  * @author Administrator
  *
  */
 class ThreadUncaughtExceptionHandler implements UncaughtExceptionHandler {

     @Override
     public void uncaughtException(Thread t, Throwable e) {
         // TODO Auto-generated method stub
         System.out.println("caught:" + e);
     }

 }

 /**
  * 线程工厂
  *
  * @author Administrator
  *
  */
 class HandlerThreadExceptionFactory implements ThreadFactory {

     @Override
     public Thread newThread(Runnable r) {
         // TODO Auto-generated method stub
         Thread t = new Thread(r);
         t.setUncaughtExceptionHandler(new ThreadUncaughtExceptionHandler());
         return t;
     }

 }

 /**
  * 线程异常捕获测试
  *
  * @author xue
  *
  */
 public class ThreadUncaughtExceptionTest implements Runnable {

     @Override
     public void run() {
         // TODO Auto-generated method stub
         throw new NullPointerException();
     }

     public static void main(String[] args) {
         ExecutorService es = Executors
                 .newCachedThreadPool(new HandlerThreadExceptionFactory());
         es.execute(new ThreadUncaughtExceptionTest());
         es.shutdown();
     }
 }

此时，我们就可以看到异常信息被捕获到了：

caught:java.lang.NullPointerException