主线程等待所有线程运行完成

	
ThreadPoolExecutor executor = new ThreadPoolExecutor(5,5, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); 
        int n = threads.size(); 
        for(int i=0; i<n; i++) { 
            executor.execute(threads.get(i)); 
        } 
        executor.shutdown(); 
        try { 
            boolean loop = true; 
            do {    //等待所有任务完成 
                loop = !executor.awaitTermination(2, TimeUnit.SECONDS); 
            } while(loop); 
        } catch (InterruptedException e) { 
        } 

	long end = System.currentTimeMillis();
	System.out.println("我是System.out.println，5个线程共运行了那么多的时间：" + (end - begin));