Java:使用Executors创建和管理线程池

>> 欢迎您客人: 登录 | 注册 | 在线 | 搜索 | 风格 | 帮助 | 统计 | 文章

返回首页

>>分享Java编程技术，对《Java面向对象编程》等书籍提供技术支持

书籍支持

卫琴直播

品书摘要

在线测试

资源下载

联系我们

Java技术网站 → 『 Java开发技术』 → 『 Java编程技术专题』 → Java:使用Executors创建和管理线程池

您是本文章第 30875 个阅读者

* 贴子主题: Java:使用Executors创建和管理线程池

点赞(0) 收藏

作者:flybird 发表时间：2020-01-08 07:49:10

消息

查看

搜索

好友

邮件

复制

引用

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×××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×××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();

         }

    }

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;

         }

    }

[code]   最低优先级:  MinPriorityThreadFactory.java

[code]    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)

----------------------------
原文链接:https://blog.51cto.com/zhangjunhd/70068

程序猿的技术大观园：www.javathinker.net

[这个贴子最后由 sunweiqin 在 2020-01-11 21:06:28 重新编辑]

Java精品书籍推荐