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)