004-多线程-JUC线程池-ThreadFactory线程工厂

一、源码分析

　　ThreadFactory是一个线程工厂。用来创建线程。这里为什么要使用线程工厂呢？其实就是为了统一在创建线程时设置一些参数，如是否守护线程。线程一些特性等，如优先级。通过这个TreadFactory创建出来的线程能保证有相同的特性。它首先是一个接口类，而且方法只有一个。就是创建一个线程。

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

1》ThreadPoolExecutor创建

    public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue) {
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
             Executors.defaultThreadFactory(), defaultHandler);
    }

最终均会调用创建以下构造方法

    public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler) {
        if (corePoolSize < 0 ||
            maximumPoolSize <= 0 ||
            maximumPoolSize < corePoolSize ||
            keepAliveTime < 0)
            throw new IllegalArgumentException();
        if (workQueue == null || threadFactory == null || handler == null)
            throw new NullPointerException();
        this.acc = System.getSecurityManager() == null ?
                null :
                AccessController.getContext();
        this.corePoolSize = corePoolSize;
        this.maximumPoolSize = maximumPoolSize;
        this.workQueue = workQueue;
        this.keepAliveTime = unit.toNanos(keepAliveTime);
        this.threadFactory = threadFactory;
        this.handler = handler;
    }

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