ServerSocket01
package socket;

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

public class ServerSocket01 {
	public static void main(String[] args) {
		ServerSocket server = null;
		try{
//			服务器在9999端口开辟了服务
			server = new ServerSocket(9999);
		}catch(Exception e){}
//		对于服务器而言，所有用户的请求都是通过ServerSocket实现
		Socket client = null;
		try{
//			服务器在此等待用户的链接
			System.out.println("等待客户端连接...");
			client = server.accept();//服务端受到的一个client
		}catch(Exception e){}
//		要向客户端打印信息
		PrintStream out = null;
//		得到向客户端输出信息的能力
		try{
			out = new PrintStream(client.getOutputStream());
		}catch(Exception e){}
		out.println("How are you ?");
		try{
			client.close();
			server.close();
		}catch(Exception e){}
		System.out.println("客户端回应完毕...");

	}

}

ClientSocket01
package socket;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Socket;

public class ClientSocket01 {
	public static void main(String[] args) {
		Socket client=null;
		try {
//			实际上表示要链接到服务器上去了
			client=new Socket("192.168.0.2",9999);
			//192.168.0.2是本人的局域网IP地址
		} catch (Exception e) {} 
//		等待服务器的回应
		String str = null;
//		如果直接使用InputStream接收会比较麻烦
		BufferedReader buf = null;
		try{
			buf = new BufferedReader(new InputStreamReader(client.getInputStream()));
			str = buf.readLine();
		}catch(Exception e){}
		System.out.println(str);
	}

}