今天来学学，大家也好对线程池有一个更好的理解。
public class Main { public static void main(String[] args) { Channel channel = new Channel(5); // 工人线程的數量,即线程池内的线程数目 channel.startWorkers();//启动线程池内的线程 new ClientThread("Alice", channel).start();//发送请求的线程，相当于向队列加入请求 new ClientThread("Bobby", channel).start(); new ClientThread("Chris", channel).start(); } }发送请求的client代码：
public class ClientThread extends Thread { private final Channel channel;//相当于线程池 private static final Random random = new Random(); public ClientThread(String name, Channel channel) { super(name); this.channel = channel; } public void run() { try { int i = 0; Request request = new Request(getName(), i);//生成请求 channel.putRequest(request);//向队列中放入请求，也即把请求传给线程池 Thread.sleep(random.nextInt(1000)); } catch (InterruptedException e) { } } }ClientThread建立请求，并把请求传给了channel，下面来看看channel类（相当于线程池类）
public class Channel { private static final int MAX_REQUEST = 100; private final Request[] requestQueue;//存放请求的队列 private int tail; // 下一个putRequest的地方 private int head; // 下一个takeRequest的地方 private int count; // Request的数量 private final WorkerThread[] threadPool; public Channel(int threads) { this.requestQueue = new Request[MAX_REQUEST]; this.head = 0; this.tail = 0; this.count = 0; threadPool = new WorkerThread[threads]; for (int i = 0; i < threadPool.length; i++) { threadPool[i] = new WorkerThread("Worker-" + i, this);//生成线程池中的线程 } } public void startWorkers() { for (int i = 0; i < threadPool.length; i++) { threadPool[i].start();//启动线程池中的线程 } } public synchronized void putRequest(Request request) {//向队列中存入请求 while (count >= requestQueue.length) { try { wait(); } catch (InterruptedException e) { } } requestQueue[tail] = request; tail = (tail + 1) % requestQueue.length; count++; notifyAll(); } public synchronized Request takeRequest() {//从队列取出请求 while (count <= 0) { try { wait(); } catch (InterruptedException e) { } } Request request = requestQueue[head]; head = (head + 1) % requestQueue.length; count--; notifyAll(); return request; } }channel类把传给他的请求放入队列中，等待worker去取请求，下面看看worker（即工作线程，线程池中已经初始话好的线程）
public class WorkerThread extends Thread { private final Channel channel; public WorkerThread(String name, Channel channel) { super(name); this.channel = channel; } public void run() { while (true) { Request request = channel.takeRequest();//取出请求 request.execute();//处理请求 } } }在工作线程中会从线程池的队列里取出请求，并对请求进行处理。这里的workerthread相当于背景线程，他一直都在运行，当有请求的时候，他就会进行处理，这里处理请求的线程是已经存在在channel（线程池里的线程），他不会因为请求的增加而增加（这是本例中的情况），不会来一个请求就新建立一个线程，节省了资源。
再看看请求的代码：
public class Request { private final String name; // 委托者 private final int number; // 请求编号 private static final Random random = new Random(); public Request(String name, int number) { this.name = name; this.number = number; } public void execute() {//执行请求 System.out.println(Thread.currentThread().getName() + " executes " + this); try { Thread.sleep(random.nextInt(1000)); } catch (InterruptedException e) { } } public String toString() { return "[ Request from " + name + " No." + number + " ]"; } }JAVA SDK所写的 ExecutorService，其就相当于channel，即线程池。至于其实现当然要比channel复杂多了，channel只是举个例子。而WorkerThread可不是工作线程，他相当于发送到channel的请求，也就是request，当执行代码：tpes.execute(workers[i]);时，相当于向线程池加入一个请求，而WorkerThread中的run则相当于request中的execute，这也是当执行tpes.execute(workers[i]);时，并不会产生新的线程的原因。ExecutorService中产生的背景线程（相当于本篇的WorkerThread ）我们是看不到的。