一 关键类的实现
1 ThreadPoolExecutor类
java.uitl.concurrent.ThreadPoolExecutor类是线程池中最核心的一个类，因此如果要透彻地了解Java中的线程池，必须先了解这个类。
下面我们来看一下ThreadPoolExecutor类的具体实现源码。
在ThreadPoolExecutor类中提供了四个构造方法：
1 public class ThreadPoolExecutor extends AbstractExecutorService { 2 ..... 3 public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit, 4 BlockingQueue<Runnable> workQueue); 5 6 public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit, 7 BlockingQueue<Runnable> workQueue,ThreadFactory threadFactory); 8 9 public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit, 10 BlockingQueue<Runnable> workQueue,RejectedExecutionHandler handler); 11 12 public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit, 13 BlockingQueue<Runnable> workQueue,ThreadFactory threadFactory,RejectedExecutionHandler handler); 14 ... 15 }