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)
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