线程池的使用

1.基本方法

1.固定大小的线程池

ExecutorService threadPool = Executors.newFixedThreadPool(int nThreads)

2.缓存线程池

ExecutorService threadPool = Executors.newCachedThreadPool()

根据需要创建一个新的线程池,当之前构造的线程可用时会重用之前的线程

3.单一线程池

ExecutorService threadPool = Executors.newSingleThreadExecutor()

思考:

如果要实现线程死掉之后重新启动的功能, 使用单一线程池是否可行?

答: 应该是可行的, 因为线程总是在不断地被创建

4.线程池的调度(schedule)

示例代码:

        //用线程池启动定时器,10s之后运行Runnable
        Executors.newScheduledThreadPool(3).schedule(new Runnable(){
                @Override
                public void run() {
                    System.out.println("shen_smile");
                }
            }, 10, TimeUnit.SECONDS);

2.全部测试代码本例中, 所有task完成之后会启动定时器, 过5s后会输出shen_smile

public class Test {
    public static void main(String[] args) {
        //单一线程池
        ExecutorService threadPool = Executors.newSingleThreadExecutor();
        for(int i=1;i<6;i++){
            final int task = i;
            threadPool.execute(new Runnable(){
                @Override
                public void run() {
                    for(int j=1;j<10;j++){
                        try {
                            Thread.sleep(20);
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                        System.out.println(Thread.currentThread().getName() + " is looping of " + j + " for task of " + task);
                    }
                }
            });
        }
        System.out.println("all of 10 tasks have committed! ");
        threadPool.shutdown();
        //用线程池启动定时器,10s之后运行Runnable
        Executors.newScheduledThreadPool(3).schedule(new Runnable(){
                @Override
                public void run() {
                    System.out.println("shen_smile");
                }
            }, 10, TimeUnit.SECONDS);
    }
}