JDK线程池的ThreadFactory

JDK线程池：Executors.newFixedThreadPool ， Executors.newSingleThreadExecutor，由一个ThreadFactory来创建新的线程，默认情况下为Executors.defaultThreadFactory(),ThreadFactory接口：

public interface ThreadFactory {
    Thread newThread(Runnable r);
}

我们可以采用自定义的ThreadFactory工厂，增加对线程创建与销毁等更多的控制，

一个简单的例子，跟踪线程的创建与销毁：

package org.guojje.threadpool;

import java.util.concurrent.atomic.AtomicInteger;

public class WorkThread extends Thread {

    private Runnable target;
    private AtomicInteger counter;

    public WorkThread(Runnable target, AtomicInteger counter) {
        this.target = target;
        this.counter = counter;
    }

    @Override
    public void run() {
        try {
            target.run();
        } finally {
            int c = counter.getAndDecrement();
            System.out.println("terminate no " + c + " Threads");
        }
    }
}

package org.guojje.threadpool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class MyThread implements Runnable {


    public static void main(String[] args) {
       ExecutorService ctp =  Executors.newCachedThreadPool(new ThreadFactory() {
            private AtomicInteger count = new AtomicInteger();
            public Thread newThread(Runnable r) {
                int c = count.incrementAndGet();
                System.out.println("create no " + c + " Threads");
                return new WorkThread(r,count);

            }
        });

       ctp.execute(new MyThread());
       ctp.execute(new MyThread());
       ctp.execute(new MyThread());
       ctp.execute(new MyThread());
       ctp.execute(new MyThread());
       ctp.execute(new MyThread());

       ctp.shutdown();
        try {
            ctp.awaitTermination(1200, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void run(){
        System.out.println("complete a task!!!");
    }
}

可以看到在执行这个过程中，共创建过几个线程。