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);