标签:Java Thread ThreadFactory 接口 DaemonThreadFactory taskId new public
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。 JDK中的介绍:An object that creates new threads on demand. Using thread factories removes hardwiring of calls tonew Thread
, enabling applications to use special thread subclasses, priorities, etc.
The simplest implementation of this interface is just:
class SimpleThreadFactory implements ThreadFactory { public Thread newThread(Runnable r) { return new Thread(r); } }
The
Executors.defaultThreadFactory
method provides a more useful simple implementation, that sets the created thread context to known values before returning it.
/** * The default thread factory */ static class DefaultThreadFactory implements ThreadFactory { static final AtomicInteger poolNumber = new AtomicInteger(1); final ThreadGroup group; final AtomicInteger threadNumber = new AtomicInteger(1); final String namePrefix; DefaultThreadFactory() { SecurityManager s = System.getSecurityManager(); group = (s != null)? s.getThreadGroup() : Thread.currentThread().getThreadGroup(); namePrefix = "pool-" + poolNumber.getAndIncrement() + "-thread-"; } public Thread newThread(Runnable r) { Thread t = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0); if (t.isDaemon()) t.setDaemon(false); if (t.getPriority() != Thread.NORM_PRIORITY) t.setPriority(Thread.NORM_PRIORITY); return t; } }
下面写一简单示例。
package com.test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.ThreadFactory; class Task implements Runnable{ int taskId; public Task(int taskId) { this.taskId=taskId; } @Override public void run() { System.out.println(Thread.currentThread().getName()+"--taskId: "+taskId); } } class DaemonThreadFactory implements ThreadFactory { @Override public Thread newThread(Runnable r) { Thread t=new Thread(r); t.setDaemon(true); return t; } } public class ThreadFactoryTest { public static void main(String[] args) { ExecutorService exec=Executors.newFixedThreadPool(3,new DaemonThreadFactory()); for(int i=0;i<3;i++) { exec.submit(new Task(i)); } exec.shutdown(); } }
输出如下: Thread-0--taskId: 0
Thread-1--taskId: 1
Thread-2--taskId: 2 分析: DaemonThreadFactory中覆写的newThread()方法与submit()方法的调用关系,也就是说DaemonThreadFactory是如何起作用的。 调试输出其调用关系: 也就是说,submit()时会调用DaemonThreadFactory类的newThread()方法来创建线程。
标签:Java,Thread,ThreadFactory,接口,DaemonThreadFactory,taskId,new,public 来源: https://www.cnblogs.com/felixzh/p/11812083.html
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