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Java:使用Executors创建和管理线程
www.jz123.cn 2009-09-08 来源: IT专家网 责任编辑(袁袁) 我要投递新闻
此类中提供的一些方法有:
1.1 public static ExecutorService newCachedThreadPool()
创建一个可根据需要创建新线程的线程池,但是在以前构造的线程可用时将重用它们。对于执行很多短期异步任务的程序而言,这些线程池通常可提高程序性能。
1.2 public static ExecutorService newFixedThreadPool(int nThreads)
创建一个可重用固定线程数的线程池,以共享的无界队列方式来运行这些线程。
1.3 public static ExecutorService newSingleThreadExecutor()
创建一个使用单个 worker 线程的 Executor,以无界队列方式来运行该线程。
这三个方法都可以配合接口ThreadFactory的实例一起使用。并且返回一个ExecutorService接口的实例。
2. 接口 ThreadFactory
根据需要创建新线程的对象。使用线程工厂就无需再手工编写对 new Thread 的调用了,从而允许应用程序使用特殊的线程子类、属性等等。
此接口最简单的实现就是:
class SimpleThreadFactory implements ThreadFactory { public Thread newThread(Runnable r) { return new Thread(r); } } |
3. 接口ExecutorService
该接口提供了管理终止的方法。
4.创建标准线程池启动线程
4.1 提供一个简单的实现Runnable接口的线程
MyThread.java package com.zj.concurrency.executors; public class MyThread implements Runnable { private int count = 1, number; public MyThread(int num) { number = num; System.out.println("Create Thread-" + number); } public void run() { while (true) { System.out.println("Thread-" + number + " run " + count+" time(s)"); if (++count == 3) return; } } } |
这个线程会打印出相应的创建和执行信息。
4.2使用CachedThreadPool启动线程
CachedThreadPool.java package com.zj.concurrency.executors; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class CachedThreadPool { public static void main(String[] args) { ExecutorService exec = Executors.newCachedThreadPool(); for (int i = 0; i < 5; i++) exec.execute(new MyThread(i)); exec.shutdown(); } } |
结果:
Create Thread-0
Create Thread-1
Create Thread-2
Create Thread-3
Thread-0 run 1 time(s)
Thread-0 run 2 time(s)
Thread-1 run 1 time(s)
Thread-1 run 2 time(s)
Thread-2 run 1 time(s)
Thread-2 run 2 time(s)
Create Thread-4
Thread-4 run 1 time(s)
Thread-4 run 2 time(s)
Thread-3 run 1 time(s)
Thread-3 run 2 time(s)
4.3 使用FixedThreadPool启动线程
FixedThreadPool.java package com.zj.concurrency.executors; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class FixedThreadPool { public static void main(String[] args) { ExecutorService exec = Executors.newFixedThreadPool(2); for (int i = 0; i < 5; i++) exec.execute(new MyThread(i)); exec.shutdown(); } } |
结果:
Create Thread-0
Create Thread-1
Create Thread-2
Create Thread-3
Create Thread-4
Thread-0 run 1 time(s)
Thread-0 run 2 time(s)
Thread-2 run 1 time(s)
Thread-2 run 2 time(s)
Thread-3 run 1 time(s)
Thread-3 run 2 time(s)
Thread-4 run 1 time(s)
Thread-4 run 2 time(s)
Thread-1 run 1 time(s)
Thread-1 run 2 time(s)
4.4 使用SingleThreadExecutor启动线程
SingleThreadExecutor.java package com.zj.concurrency.executors; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class SingleThreadExecutor { public static void main(String[] args) { ExecutorService exec = Executors.newSingleThreadExecutor(); for (int i = 0; i < 5; i++) exec.execute(new MyThread(i)); exec.shutdown(); } } |
结果:
Create Thread-0
Create Thread-1
Create Thread-2
Create Thread-3
Create Thread-4
Thread-0 run 1 time(s)
Thread-0 run 2 time(s)
Thread-1 run 1 time(s)
Thread-1 run 2 time(s)
Thread-2 run 1 time(s)
Thread-2 run 2 time(s)
Thread-3 run 1 time(s)
Thread-3 run 2 time(s)
Thread-4 run 1 time(s)
Thread-4 run 2 time(s)
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