3.6.3 使用JDK类库提供的线程池

package multithread3;
import java.io.*;
import java.net.*;
import java.util.concurrent.*;

public class EchoServer {
private int port=8000;
private ServerSocket serverSocket;
private ExecutorService executorService;    //线程池
private final int POOL_SIZE=4;      //单个CPU时线程池中工作线程的数目

  public EchoServer() throws IOException {
serverSocket = new ServerSocket(port);
//创建线程池
//Runtime的availableProcessors()方法返回当前系统的CPU的数目
//系统的CPU越多，线程池中工作线程的数目也越多 
executorService= Executors.newFixedThreadPool( 
Runtime.getRuntime().availableProcessors() * POOL_SIZE);

    System.out.println("服务器启动");
}

  public void service() {
while (true) {
Socket socket=null;
try {
socket = serverSocket.accept();
executorService.execute(new Handler(socket));
}catch (IOException e) {
e.printStackTrace();
}
}
}

  public static void main(String args[])throws IOException {
new EchoServer().service();
}
}

/** 负责与单个客户通信的任务，代码与3.6.1节的例程3-5的Handler类相同 */
class Handler implements Runnable{…}