四种线程池实例

1、固定线程池：

package concurrent.threadpool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
 * 固定线程池
 * 使用Executors.newFixedThreadPool(3)方法指定池中允许执行线程的个数
 * 如果超过这个线程个数,后面的线程就会等待
 */
public class FixedThreadPoolTest {
	public static void main(String[] args) {
		//创建一个初始线程为3个的线程池
		ExecutorService pool=Executors.newFixedThreadPool(3);
		for(int i=0;i<10;i++){
			final int task=i;
			pool.execute(new Runnable() {
				@Override
				public void run() {
					try {
						Thread.sleep(20);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					for(int j=0;j<10;j++){
						System.out.println(Thread.currentThread().getName()+"正在进行第"+task+"个任务,第"+j+"次循环");
					}
				}
			});
		}
		System.out.println("all of ten tasks have committed");
		//关闭线程池
		pool.shutdown();
	}
}

2、缓存线程池：

package concurrent.threadpool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
 * 缓存线程池
 * 如果池中的线程不够,会自动增加线程
 */
public class CachedThreadPoolTest {
	public static void main(String[] args) {
		//创建一个缓存线程池
		ExecutorService pool=Executors.newCachedThreadPool();
		for(int i=0;i<10;i++){
			final int task=i;
			pool.execute(new Runnable() {
				@Override
				public void run() {
					try {
						Thread.sleep(20);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					for(int j=0;j<10;j++){
						System.out.println(Thread.currentThread().getName()+"正在进行第"+task+"个任务,第"+j+"次循环");
					}
				}
			});
		}
		System.out.println("all of ten tasks have committed");
	}
}

3、定时器线程池：

package concurrent.threadpool;

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
/**
 * 定时器线程池
 *
 */
public class ScheduledThreadPoolTest {
	public static void main(String[] args) {
//		method1();
		method2();
	}
	
	/**
	 * 2秒之后执行线程
	 */
	public static void method1(){
		ScheduledExecutorService pool = Executors.newScheduledThreadPool(3);
		//2秒之后执行这个线程
		pool.schedule(new Runnable() {
			@Override
			public void run() {
				System.out.println("爆炸");
			}
		}, 2, TimeUnit.SECONDS);
	}
	
	/**
	 * 5秒后第一次执行线程，之后每隔2秒执行一次
	 * 也就是5秒后打印第一次爆炸，之后每隔2秒打印一次爆炸
	 */
	public static void method2(){
		ScheduledExecutorService pool = Executors.newScheduledThreadPool(3);
		pool.scheduleAtFixedRate(new Runnable() {
			@Override
			public void run() {
				System.out.println("爆炸");
			}
		}, 5, 2, TimeUnit.SECONDS);
	}
}

4、单线程池：

package concurrent.threadpool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
 * 只有一个线程工作的线程池
 * 始终保持池中有一个线程，当一个线程死了会立即重新创建一个线程
 */
public class SingleThreadExecutorTest {
	public static void main(String[] args) {
		ExecutorService pool=Executors.newSingleThreadExecutor();
		for(int i=0;i<10;i++){
			final int task=i;
			pool.execute(new Runnable() {
				@Override
				public void run() {
					try {
						Thread.sleep(20);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					for(int j=0;j<10;j++){
						System.out.println(Thread.currentThread().getName()+"正在进行第"+task+"个任务,第"+j+"次循环");
					}
				}
			});
		}
		System.out.println("all of ten tasks have committed");
	}
}