Java多线程——Executors和线程池

线程池的概念与Executors类的应用

　　1.创建固定大小的线程池

package java_thread;

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

public class ThreadPoolTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		ExecutorService threadPool = Executors.newFixedThreadPool(3);
//		ExecutorService threadPool = Executors.newCachedThreadPool();
//		ExecutorService threadPool = Executors.newSingleThreadExecutor();
		for(int i=1;i<=10;i++){
			final int task = i;
			threadPool.execute(new Runnable(){
				@Override
				public void run() {
					for(int j=1;j<=4;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.shutdownNow();

//		Executors.newScheduledThreadPool(3).scheduleAtFixedRate(
//				new Runnable(){
//					@Override
//				public void run() {
//					System.out.println("bombing!");
//
//				}},
//				6,
//				2,
//				TimeUnit.SECONDS);
	}

}

　　2.创建缓存线程池

ExecutorService threadPool = Executors.newCachedThreadPool();

　3.创建单一线程池

ExecutorService threadPool = Executors.newSingleThreadExecutor();

关闭线程池

　　shutdown与shutdownNow的比较

threadPool.shutdownNow();

用线程池启动定时器

　　调用ScheduledExecutorService的schedule方法，返回的ScheduleFuture对象可以取消任务。

　　支持间隔重复任务的定时方式，不直接支持绝对定时方式，需要转换成相对时间方式。

		Executors.newScheduledThreadPool(3).scheduleAtFixedRate(	//多久气候执行，每隔多久执行
				new Runnable(){
					@Override
				public void run() {
					System.out.println("bombing!");

				}},
				6,
				2,
				TimeUnit.SECONDS);