施用Executors创建和管理线程

使用Executors创建和管理线程
http://zhangjunhd.blog.51cto.com/113473/70068

1. 类 Executors
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)

5.配合ThreadFactory接口的使用
我们试图给线程加入daemon和priority的属性设置。
5.1设置后台线程属性
DaemonThreadFactory.java

package com.zj.concurrency.executors.factory;import java.util.concurrent.ThreadFactory; public class DaemonThreadFactory implements ThreadFactory {    public Thread newThread(Runnable r) {       Thread t = new Thread(r);       t.setDaemon(true);       return t;    }}

5.2 设置优先级属性
最高优先级MaxPriorityThreadFactory.java

package com.zj.concurrency.executors.factory;import java.util.concurrent.ThreadFactory; public class MaxPriorityThreadFactory implements ThreadFactory {    public Thread newThread(Runnable r) {       Thread t = new Thread(r);       t.setPriority(Thread.MAX_PRIORITY);       return t;    }}

最低优先级MinPriorityThreadFactory.java

package com.zj.concurrency.executors.factory;import java.util.concurrent.ThreadFactory; public class MinPriorityThreadFactory implements ThreadFactory {    public Thread newThread(Runnable r) {       Thread t = new Thread(r);       t.setPriority(Thread.MIN_PRIORITY);       return t;    }}

5.3启动带有属性设置的线程
ExecFromFactory.java

package com.zj.concurrency.executors;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import com.zj.concurrency.executors.factory.DaemonThreadFactory;import com.zj.concurrency.executors.factory.MaxPriorityThreadFactory;import com.zj.concurrency.executors.factory.MinPriorityThreadFactory; public class ExecFromFactory {    public static void main(String[] args) throws Exception {       ExecutorService defaultExec = Executors.newCachedThreadPool();       ExecutorService daemonExec = Executors              .newCachedThreadPool(new DaemonThreadFactory());       ExecutorService maxPriorityExec = Executors              .newCachedThreadPool(new MaxPriorityThreadFactory());       ExecutorService minPriorityExec = Executors              .newCachedThreadPool(new MinPriorityThreadFactory());       for (int i = 0; i < 10; i++)           daemonExec.execute(new MyThread(i));       for (int i = 10; i < 20; i++)           if (i == 10)              maxPriorityExec.execute(new MyThread(i));           else if (i == 11)              minPriorityExec.execute(new MyThread(i));           else              defaultExec.execute(new MyThread(i));    }}

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)
Create Thread-5
Thread-5 run 1 time(s)
Thread-5 run 2 time(s)
Create Thread-6
Create Thread-7
Thread-7 run 1 time(s)
Thread-7 run 2 time(s)
Create Thread-8
Thread-8 run 1 time(s)
Thread-8 run 2 time(s)
Create Thread-9
Create Thread-10
Thread-10 run 1 time(s)
Thread-10 run 2 time(s)
Create Thread-11
Thread-9 run 1 time(s)
Thread-9 run 2 time(s)
Thread-6 run 1 time(s)
Thread-6 run 2 time(s)
Thread-3 run 1 time(s)
Thread-3 run 2 time(s)
Create Thread-12
Create Thread-13
Create Thread-14
Thread-12 run 1 time(s)
Thread-12 run 2 time(s)
Thread-13 run 1 time(s)
Thread-13 run 2 time(s)
Create Thread-15
Thread-15 run 1 time(s)
Thread-15 run 2 time(s)
Create Thread-16
Thread-16 run 1 time(s)
Thread-16 run 2 time(s)
Create Thread-17
Create Thread-18
Create Thread-19
Thread-14 run 1 time(s)
Thread-14 run 2 time(s)
Thread-17 run 1 time(s)
Thread-17 run 2 time(s)
Thread-18 run 1 time(s)
Thread-18 run 2 time(s)
Thread-19 run 1 time(s)
Thread-19 run 2 time(s)
Thread-11 run 1 time(s)
Thread-11 run 2 time(s)

查看更多 下一篇