所謂簡單是指的是：
1、伺服器一次只能響應一個客戶端的請求，直到和客戶端斷開連結才可以響應下一個客戶端請求。不能多客戶端連結伺服器

客戶端：

我們是在本機上做的測試，所以客戶端所連結的host地址是用的127.0.0.1這個迴環地址。埠好使用1023以上的，1023以下的埠號被系統保留。

package socket.client;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import
 
 java.net.Socket;
import java.net.UnknownHostException;
import java.util.Calendar;

public class socketclientDemo {

    public socketclientDemo(){

    }
    public static void main(String[] args){
    /*
    *這一部分是用於獲取命令列引數用的，如果為輸入引數，那麼自動列印本機主機名/ip地址
    */
        if(args.length>0)
        {

        }
        else
 

        {
            try {
                InetAddress localHostAddress=InetAddress.getLocalHost();
                System.out.println(localHostAddress.toString());
            } catch (UnknownHostException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        try
 
 {
            //客戶端開啟一個socket
            Socket  socket=new Socket("127.0.1.1",  2016);
            socket.setSoTimeout(6000);
            //開啟socket對應的輸出和輸入流
            PrintWriter pw =new PrintWriter(socket.getOutputStream(),true);
            BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
            //給伺服器傳送資訊，可以看到和JAVA IO基本是一樣的
            pw.println(br.readLine()+Calendar.getInstance().getTime().toString());
            //pw.println(Calendar.getInstance().getTime().toString());
            pw.flush();

            /**
             * 獲取伺服器發過來的資訊
             */
            BufferedReader bufferedReader= new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String result=bufferedReader.readLine();
            System.out.println("Server say"+result);

            pw.close();
            bufferedReader.close();
            socket.close();


        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

伺服器端程式

package server.socket;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Calendar;

public class ServerSocketDemo {

    public ServerSocketDemo() {
    // TODO Auto-generated constructor stub
    }

    public static void main(String[] args) {
    // TODO Auto-generated method stub
    try {
    //伺服器開啟一個serversocket監聽2016埠，
        ServerSocket serverSocket = new ServerSocket(2016);
        while (true) {
        //accept函式會一直阻塞這裡，直到監聽到客戶端請求然後返回一個socket，用於雙方之間的通訊。建立連線後雙方都是用socket進行通訊，是平等的關係。
        Socket socket = serverSocket.accept();
        /**
         * 獲取客戶端傳送過來的資訊，先獲取輸入流，
         */
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        String resultString = bufferedReader.readLine();
        System.out.println("Client say\t" + resultString);
        /**
         * 伺服器傳送資訊給客戶端，先獲取輸出流
         */
        PrintWriter printWriter = new PrintWriter(socket.getOutputStream());
        printWriter.println("hello , i'm  server" + Calendar.getInstance().getTime().toString());
        printWriter.flush();

        printWriter.close();
        bufferedReader.close();
        socket.close();

        }
    } catch (Exception e) {
        // TODO: handle exception
        System.out.println("Exception" + e.getMessage());
    }

    }

}