所属包：
java.util.concurrent.ThreadPoolExecutor
类关系：
public class ThreadPoolExecutor extends
1. 继承关系
ThreadPoolExecutor 继承了一个抽象类：AbstractExecutorService
public abstract class AbstractExecutorService implements ExecutorService
而这个AbstractExecutorService实现了一个接口：ExecutorService
public interface ExecutorService extends Executor
这个ExecutorService接口又继承了一个类：Executor
public interface Executor
可以看出：
Executor是一个顶层接口，它的子接口ExecutorService继承了它（其实还有一个子接口： ScheduledExecutorService），抽象类AbstractExecutorService实现了这个子接口ExecutorService，最终ThreadPoolExecutor 继承了抽象类AbstractExecutorService并且同时实现了子接口ExecutorService。
2. 构造方法
最简单的一个构造方法：
/** * Creates a new { @code ThreadPoolExecutor} with the given initial * parameters and default thread factory and rejected execution handler. * It may be more convenient to use one of the { @link Executors} factory * methods instead of this general purpose constructor. * * @param corePoolSize the number of threads to keep in the pool, even * if they are idle, unless { @code allowCoreThreadTimeOut} is set * @param maximumPoolSize the maximum number of threads to allow in the * pool * @param keepAliveTime when the number of threads is greater than * the core, this is the maximum time that excess idle threads * will wait for new tasks before terminating. * @param unit the time unit for the { @code keepAliveTime} argument * @param workQueue the queue to use for holding tasks before they are * executed. This queue will hold only the { @code Runnable} * tasks submitted by the { @code execute} method. * @throws IllegalArgumentException if one of the following holds: * { @code corePoolSize < 0} * { @code keepAliveTime < 0} * { @code maximumPoolSize <= 0} * { @code maximumPoolSize < corePoolSize} * @throws NullPointerException if { @code workQueue} is null */ public ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue) { this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, Executors.defaultThreadFactory(), defaultHandler); }
有五个参数：
corePoolSize - 即使空闲时仍保留在池中的线程数，除非设置 allowCoreThreadTimeOut maximumPoolSize - 池中允许的最大线程数 keepAliveTime - 当线程数大于核心时，这是多余的空闲线程在终止之前等待新任务的最大时间。 unit - keepAliveTime参数的时间单位 workQueue - 在执行任务之前用于保存任务的队列。 该队列将仅保存execute方法提交的Runnable任务
实际上它调用了同类的另外一个“全能”构造方法，通过 this() 的形式，最后两个参数用的默认值
另外一个构造方法：
/** * Creates a new { @code ThreadPoolExecutor} with the given initial * parameters. * * @param corePoolSize the number of threads to keep in the pool, even * if they are idle, unless { @code allowCoreThreadTimeOut} is set * @param maximumPoolSize the maximum number of threads to allow in the * pool * @param keepAliveTime when the number of threads is greater than * the core, this is the maximum time that excess idle threads * will wait for new tasks before terminating. * @param unit the time unit for the { @code keepAliveTime} argument * @param workQueue the queue to use for holding tasks before they are * executed. This queue will hold only the { @code Runnable} * tasks submitted by the { @code execute} method. * @param threadFactory the factory to use when the executor * creates a new thread * @param handler the handler to use when execution is blocked * because the thread bounds and queue capacities are reached * @throws IllegalArgumentException if one of the following holds: * { @code corePoolSize < 0} * { @code keepAliveTime < 0} * { @code maximumPoolSize <= 0} * { @code maximumPoolSize < corePoolSize} * @throws NullPointerException if { @code workQueue} * or { @code threadFactory} or { @code handler} is null */ public ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue 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.corePoolSize = corePoolSize; this.maximumPoolSize = maximumPoolSize; this.workQueue = workQueue; this.keepAliveTime = unit.toNanos(keepAliveTime); this.threadFactory = threadFactory; this.handler = handler; }
参数：
corePoolSize - 即使空闲时仍保留在池中的线程数，除非设置 allowCoreThreadTimeOut maximumPoolSize - 池中允许的最大线程数 keepAliveTime - 当线程数大于内核时，这是多余的空闲线程在终止前等待新任务的最大时间。 unit - keepAliveTime参数的时间单位 workQueue - 用于在执行任务之前使用的队列。 这个队列将仅保存execute方法提交的Runnable任务。 threadFactory - 执行程序创建新线程时使用的工厂 handler - 执行被阻止时使用的处理程序，因为达到线程限制和队列容量
3. 如何使用
import java.util.concurrent.ArrayBlockingQueue;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit;public class MyThreadPoolExecutor { /** * 使用有界队列： * 1、当线程数小于corePoolSize时，创建线程执行任务。 * 2、当线程数大于等于corePoolSize并且workQueue没有满时，放入workQueue中 * 3、线程数大于等于corePoolSize并且当workQueue满时，新任务新建线程运行，线程总数要小于maximumPoolSize * 4、当线程总数等于maximumPoolSize并且workQueue满了的时候执行handler的rejectedExecution。也就是拒绝策略。 * * ThreadPoolExecutor默认有四个拒绝策略： * 1、ThreadPoolExecutor.AbortPolicy() 直接抛出异常RejectedExecutionException * 2、ThreadPoolExecutor.CallerRunsPolicy() 直接调用run方法并且阻塞执行 * 3、ThreadPoolExecutor.DiscardPolicy() 直接丢弃后来的任务 * 4、ThreadPoolExecutor.DiscardOldestPolicy() 丢弃在队列中队首的任务 * * * */ public static void main(String[] args) { ThreadPoolExecutor pool = new ThreadPoolExecutor( 1, 2, 0L, TimeUnit.SECONDS, new ArrayBlockingQueue<>(3)); Runnable[] runs = new Runnable[6]; for (int i = 0; i < runs.length; i++) { runs[i] = new MyTask(i); } pool.execute(runs[0]); //线程1个，队列0个 pool.execute(runs[1]); //线程1个，队列1个 pool.execute(runs[2]); //线程1个，队列2个 pool.execute(runs[3]); //线程1个，队列3个 pool.execute(runs[4]); //线程2个，队列3个 pool.execute(runs[5]); //线程2个，队列3个，拒绝第六个 pool.shutdown(); }}
线程：
public class MyTask implements Runnable { private int id; public MyTask(int id) { this.id = id; } @Override public void run() { try { Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Task-" + id); }}
这个就是最简单的一个使用方法了。ps：最后那个（线程1个，队列0个....）指的是，你仅仅执行runs[0]；runs[0]+runs[1]；runs[0]+runs[1]+runs[2]；....的时候，任务被放到哪里。
但是推荐使用这种方式创建线程池：
package cn.ying.thread.pool;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class MyTest { public static void main(String[] args) { ExecutorService pool = Executors.newFixedThreadPool(5); for (int i = 0; i < 10; i++) { pool.execute(new MyTask(i)); } pool.shutdown(); } public void note(){ Executors.newCachedThreadPool(); //无界线程池，可以进行自动线程回收// public static ExecutorService newCachedThreadPool() {// return new ThreadPoolExecutor(0, Integer.MAX_VALUE,// 60L, TimeUnit.SECONDS,// new SynchronousQueue ());//SynchronousQueue:长度为1的队列// } Executors.newFixedThreadPool(10); //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。// public static ExecutorService newFixedThreadPool(int nThreads) {// return new ThreadPoolExecutor(nThreads, nThreads,// 0L, TimeUnit.MILLISECONDS,// new LinkedBlockingQueue ());// } Executors.newScheduledThreadPool(10); //创建一个单线程执行程序，它可安排在给定延迟后运行命令或者定期地执行// public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {// return new ScheduledThreadPoolExecutor(corePoolSize);// }// public ScheduledThreadPoolExecutor(int corePoolSize) {// super(corePoolSize, Integer.MAX_VALUE, 0, NANOSECONDS,// new DelayedWorkQueue());// } Executors.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// public static ExecutorService newSingleThreadExecutor() {// return new FinalizableDelegatedExecutorService// (new ThreadPoolExecutor(1, 1,// 0L, TimeUnit.MILLISECONDS,// new LinkedBlockingQueue ()));// } }}
main方法里面就是相关代码，而note方法则是简单介绍几种方法，注释部分是源码。
就先写这么多吧，以后再补充