案例：在案例1的基础上实现一个服务器对应多个客户端（多线程），且获得每个客户端的IP。
线程代码：
package com.yh.mySocket;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.net.InetAddress;import java.net.Socket;public class LoginThread extends Thread { Socket socket = null; public LoginThread() {} public LoginThread(Socket socket) { this.socket = socket; } @Override public void run() { // TODO Auto-generated method stub try { // 获得输入流，获得相应的用户请求 InputStream is = socket.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(is)); String info; while((info = br.readLine())!=null) { System.out.println(info); } // 获得客户端IP InetAddress ia = socket.getInetAddress(); String ip = ia.getHostAddress(); System.out.println("客户端IP地址为："+ip); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } }} 客户端代码（多个客户端代码类似）：
package com.yh.mySocket;import java.io.IOException;import java.io.OutputStream;import java.net.Socket;import java.net.UnknownHostException;public class LoginClient1 { public static void main(String[] args) { Socket socket = null; OutputStream os = null; try { // 创建一个客户端Socket，参数为客户端IP和指定端口号，此处客户端和服务器在同一台电脑，所以IP地址相同 socket = new Socket("localhost",5000); // 通过输出流，给服务器发送请求 os = socket.getOutputStream(); String info = "用户名：YeHuan1; 密码：12345"; byte[] infos = info.getBytes(); os.write(infos); } catch (UnknownHostException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { os.close(); socket.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }} 服务器代码：
package com.yh.mySocket;import java.io.*;import java.net.ServerSocket;import java.net.Socket;public class LoginServer { public static void main(String[] args) { ServerSocket serversocket = null; Socket socket = null; try { // 创建一个服务器Socket serversocket = new ServerSocket(5000); while(true) { // 使用accept()等待用户的通信 socket = serversocket.accept(); LoginThread lt = new LoginThread(socket); lt.start(); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { // 释放资源 socket.close(); serversocket.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }}