简单Echo服务器

package zhc.Net;

import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

/**
 * 简单的Echo服务器
 */
public class EchoServer {
    public static void main(String[] args) {
        try {
            ServerSocket s = new ServerSocket(8189);
            InetAddress localHostAddress = InetAddress.getLocalHost();
            System.out.println(localHostAddress);
            //accept 只执行一次这里只能服务一个用户
            Socket incoming  = s.accept();
            try {
                    InputStream inStream = incoming.getInputStream();
                    OutputStream outStream = incoming.getOutputStream();

                    Scanner in = new Scanner(inStream);
                    PrintWriter out = new PrintWriter(outStream, true);

                    out.println("Hello! Enter BYE to exit.");

                    boolean done = false;
                    //轮询直到用户输入 BYE 结束循环关闭套接字
                    while (!done && in.hasNextLine()) {
                        String line = in.nextLine();
                        out.println("Echo " + line);
                        if (line.trim().equals("BYE"))
                            done = true;
                    }
            }finally {
                incoming.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

多线程 Echo服务器

package zhc.Net;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 同时服务多个客户端的Echo服务器
 */
public class EchoServer2 {
    public static void main(String[] args) {
        try {
            int i = 1;
            ServerSocket s = new ServerSocket(8189);
            while(true) {
                Socket incoming = s.accept();
                System.out.println("Spawning" + i);
                Runnable r = new ThreadEchoHandler(incoming);
                Thread t = new Thread(r);
                t.start();
                i++;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

package zhc.Net;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class ThreadEchoHandler implements Runnable{
    public ThreadEchoHandler(Socket i) {
        incoming = i;
    }
    @Override
    public void run() {
        try {
            try {
                InputStream inStream = incoming.getInputStream();
                OutputStream outStream = incoming.getOutputStream();

                Scanner in = new Scanner(inStream);
                PrintWriter out = new PrintWriter(outStream, true);

                out.println("Hello! Enter BYE to exit.");

                boolean done = false;
                //轮询直到用户输入 BYE 结束循环关闭套接字
                while (!done && in.hasNextLine()) {
                    String line = in.nextLine();
                    out.println("Echo " + line);
                    if (line.trim().equals("BYE"))
                        done = true;
                }
            } finally {
                incoming.close();
            }
        }catch (IOException e) {
            e.printStackTrace();
        }
    }
    private Socket incoming;
}