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Java:使用Executors创建和管理线程

2008-10-24 17:34 525 查看

1. 类 Executors<?XML:NAMESPACE PREFIX = O />

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

[align=left]package com.zj.concurrency.executors;
[/align]
[align=left]
[/align]
[align=left]public class MyThread implements Runnable {
[/align]
[align=left]    private int count = 1, number;
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[align=left]
[/align]
[align=left]    public MyThread(int num) {
[/align]
[align=left]       number = num;
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[align=left]       System.out.println("Create Thread-" + number);
[/align]
[align=left]    }
[/align]
[align=left]
[/align]
[align=left]    public void run() {
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[align=left]       while (true) {
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[align=left]           System.out.println("Thread-" + number + " run " + count+" time(s)");
[/align]
[align=left]           if (++count == 3)
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[align=left]              return;
[/align]
[align=left]       }
[/align]
[align=left]    }
[/align]
}

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

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

5.2 设置优先级属性

最高优先级MaxPriorityThreadFactory.java

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

最低优先级MinPriorityThreadFactory.java

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

5.3启动带有属性设置的线程

ExecFromFactory.java

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

结果：
[align=left]Create Thread-0
[/align]
[align=left]Create Thread-1
[/align]
[align=left]Create Thread-2
[/align]
[align=left]Create Thread-3
[/align]
[align=left]Thread-0 run 1 time(s)
[/align]
[align=left]Thread-0 run 2 time(s)
[/align]
[align=left]Thread-1 run 1 time(s)
[/align]
[align=left]Thread-1 run 2 time(s)
[/align]
[align=left]Thread-2 run 1 time(s)
[/align]
[align=left]Thread-2 run 2 time(s)
[/align]
[align=left]Create Thread-4
[/align]
[align=left]Thread-4 run 1 time(s)
[/align]
[align=left]Thread-4 run 2 time(s)
[/align]
[align=left]Create Thread-5
[/align]
[align=left]Thread-5 run 1 time(s)
[/align]
[align=left]Thread-5 run 2 time(s)
[/align]
[align=left]Create Thread-6
[/align]
[align=left]Create Thread-7
[/align]
[align=left]Thread-7 run 1 time(s)
[/align]
[align=left]Thread-7 run 2 time(s)
[/align]
[align=left]Create Thread-8
[/align]
[align=left]Thread-8 run 1 time(s)
[/align]
[align=left]Thread-8 run 2 time(s)
[/align]
[align=left]Create Thread-9
[/align]
[align=left]Create Thread-10
[/align]
[align=left]Thread-10 run 1 time(s)
[/align]
[align=left]Thread-10 run 2 time(s)
[/align]
[align=left]Create Thread-11
[/align]
[align=left]Thread-9 run 1 time(s)
[/align]
[align=left]Thread-9 run 2 time(s)
[/align]
[align=left]Thread-6 run 1 time(s)
[/align]
[align=left]Thread-6 run 2 time(s)
[/align]
[align=left]Thread-3 run 1 time(s)
[/align]
[align=left]Thread-3 run 2 time(s)
[/align]
[align=left]Create Thread-12
[/align]
[align=left]Create Thread-13
[/align]
[align=left]Create Thread-14
[/align]
[align=left]Thread-12 run 1 time(s)
[/align]
[align=left]Thread-12 run 2 time(s)
[/align]
[align=left]Thread-13 run 1 time(s)
[/align]
[align=left]Thread-13 run 2 time(s)
[/align]
[align=left]Create Thread-15
[/align]
[align=left]Thread-15 run 1 time(s)
[/align]
[align=left]Thread-15 run 2 time(s)
[/align]
[align=left]Create Thread-16
[/align]
[align=left]Thread-16 run 1 time(s)
[/align]
[align=left]Thread-16 run 2 time(s)
[/align]
[align=left]Create Thread-17
[/align]
[align=left]Create Thread-18
[/align]
[align=left]Create Thread-19
[/align]
[align=left]Thread-14 run 1 time(s)
[/align]
[align=left]Thread-14 run 2 time(s)
[/align]
[align=left]Thread-17 run 1 time(s)
[/align]
[align=left]Thread-17 run 2 time(s)
[/align]
[align=left]Thread-18 run 1 time(s)
[/align]
[align=left]Thread-18 run 2 time(s)
[/align]
[align=left]Thread-19 run 1 time(s)
[/align]
[align=left]Thread-19 run 2 time(s)
[/align]
[align=left]Thread-11 run 1 time(s)
[/align]
[align=left]Thread-11 run 2 time(s)
[/align]
本文出自 “子孑” 博客，出处http://zhangjunhd.blog.51cto.com/113473/70068

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标签： java thread class string exception 任务

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