学步园

    对于Thread，它既是工作单元(含有run方法)，也是执行机制(start方法)。而executor framework将两者解耦，实现了工作单元和执行机制的分离。executor负责执行任务,runnable和callable代表业务逻辑单元（前者无返回值，后者有返回值)。使用executor framework，我们无须再手动创建Thread，因为executor framework有一个专门负责创建线程的接口-ThreadFactory，该接口只声明了一个方法 - newThread，负责返回一个线程。一个简单的实现是：

class SimpleThreadFactory implements ThreadFactory {
	
	@Override
	public Thread newThread(Runnable r) {
		return new Thread(r);
	}
}

 如果我们在使用executors工具类创建具体的executor时，如果没有显式告诉自定义的ThreadFactory时，则使用默认的线程工厂：

    static class DefaultThreadFactory implements ThreadFactory {
        private static final AtomicInteger poolNumber = new AtomicInteger(1);
        private final ThreadGroup group;
        private final AtomicInteger threadNumber = new AtomicInteger(1);
        private final String namePrefix;

        DefaultThreadFactory() {
            SecurityManager s = System.getSecurityManager();
            group = (s != null) ? s.getThreadGroup() :
                                  Thread.currentThread().getThreadGroup();
            namePrefix = "pool-" +
                          poolNumber.getAndIncrement() +
                         "-thread-";
        }

        public Thread newThread(Runnable r) {
            Thread t = new Thread(group, r,
                                  namePrefix + threadNumber.getAndIncrement(),
                                  0);
            if (t.isDaemon())
                t.setDaemon(false);
            if (t.getPriority() != Thread.NORM_PRIORITY)
                t.setPriority(Thread.NORM_PRIORITY);
            return t;
        }
    }

如果想自定义线程工厂，则需提供一个实现了ThreadFactory的类（如上面的SimpleThreadFactory)，然后当我们创建具体的executor时：

		ExecutorService executor = Executors.newCachedThreadPool(new SimpleThreadFactory());
		ExecutorService executor = Executors.newSingleThreadExecutor(new SimpleThreadFactory());
		ExecutorService executor = Executors.newFixedThreadPool(10, new SimpleThreadFactory());
		ExecutorService executor = Executors.newScheduledThreadPool(10, new SimpleThreadFactory());

这样，就会使用自定义的线程工厂来创建线程。