Java:使用Executors创建和管理线程_JAVA_编程开发_程序员俱乐部

Java:使用Executors创建和管理线程 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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