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