一、服務端程式碼

import java.net.ServerSocket;
import java.net.Socket;
import java.io.IOException;
import java.io.InputStream;
import java.util.Scanner;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

/**
 * Description：
 * 實現一個Socket服務端
 * @author Lee
 * */

public
 
 class Server {

    /**
     * Description：
     * 實現一個Socket服務端
     * */
    public static void test1(){ 
        ServerSocket server = null;
        Socket client = null;
        PrintWriter  output  = null;
        Scanner input = null;
        Scanner keyboard = null;
        try{
            //以指定的埠建立一個Socket服務端
 

            server = new ServerSocket(12000);

            while(true){
                //獲取一個Socket客戶端例項
                client = server.accept();

                //獲取客戶端的IP地址，連線埠
                System.out.println("已經連線上"+client.getInetAddress()
                                        +"客戶端，埠為："+client.getPort());

                //監聽客戶端的輸入
 

                input = new Scanner(client.getInputStream());
                //監聽客戶端的輸出
                output = new PrintWriter(client.getOutputStream());
                //監聽服務端的鍵盤輸入
                keyboard = new Scanner(System.in);

                //readLine 要等待換行符才會終止,因此只有當客戶端輸入的字元中換行符才會結束讀取完資料
                /*
                A line is considered to be terminated by any one
                of a line feed ('\n'), a carriage return ('\r'), or a carriage return
                followed immediately by a linefeed. 
                */
//              BufferedReader re = new BufferedReader(new InputStreamReader(input));               
//              String line = null;
//              while((line=re.readLine())!=null){
//                  System.out.println("client:"+line);
//              }

                //同樣的Scanner當沒有遇到換行符的時候，會快取所有讀取的資料，當結束程式的時候則會釋放出來。
                /*
                it may buffer all of the input searching for the line to skip 
                if no line separators are present
                */

                //等待客戶端的輸入  
                while(input.hasNext()){
                    System.out.println("CLIENT:"+input.nextLine());

                    //讀取鍵盤輸入
                    String line = "";
                    System.out.print("SERVER:");
                    if(keyboard.hasNext()){
                        line =keyboard.nextLine();

                        //將鍵盤輸入的內容輸出給客戶端
                        output.println(line);
                        output.flush();
                    }
                }   
            }

        }catch(IOException e){
            e.printStackTrace();
        }finally{

            //關閉資源
            try{
                server.close();
                client.close();
                input.close();
                output.close();
                keyboard.close();

            }catch(IOException e){
                e.printStackTrace();
            }
        }

    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        test1();
    }

}

二、客戶

import java.net.Socket;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.io.InputStream;
import java.util.Scanner;
import java.io.OutputStream;
import java.io.FileInputStream;
import java.io.PrintWriter;
import java.io.InputStreamReader;
import java.io.InterruptedIOException;
import java.io.BufferedReader;
 * Description:
 * 實現一個Socket客戶端
 * @author Lee
 * */

public class Client {

    /**
     * Description:
     * 實現一個Socket客戶端
     * */
    public static void test1(){
        Socket server = null;
        PrintWriter output = null;
        Scanner input = null;
        Scanner keyboard = null;

        try{
            server = new Socket();
            //連線遠端服務端   
            server.connect(new InetSocketAddress("192.168.20.59",12000));

            //獲取遠端服務端的IP地址和埠   
            System.out.println("已經連線上"+server.getInetAddress()
            +"服務端，埠為："+server.getPort());

            //監聽輸出流
            output = new PrintWriter(server.getOutputStream());
            //監聽輸入流
            input = new Scanner(server.getInputStream());
            //監聽鍵盤的輸入流
            keyboard = new Scanner(System.in);

            //等待鍵盤輸入
            System.out.print("CLIENT:");
            while(keyboard.hasNext()){
                String line = keyboard.nextLine();

                /* 原始碼：
                public void print(String s) {
                    if (s == null) {
                        s = "null";
                    }
                    write(s);
                }
                public void println() {
                    newLine();
                }   
                public void println(boolean x) {
                    synchronized (lock) {
                        print(x);
                        println();
                    }
                }   
                private void newLine() {
                    try {
                        synchronized (lock) {
                            ensureOpen();
                            //這裡加上了換行符，因此readLine才能夠完成讀取
                            out.write(lineSeparator);
                            if (autoFlush)
                                out.flush();
                        }
                    }
                    catch (InterruptedIOException x) {
                        Thread.currentThread().interrupt();
                    }
                    catch (IOException x) {
                        trouble = true;
                    }
                }
                */
                //使用readLine方法的時候，是需要換行符在終止讀取資料的。

                //鍵盤盤輸入的內容輸出給服務端
                output.print(line+"\n");
                //print.println(line);  
                output.flush();

                //等待服務端輸入流
                if(input.hasNext())
                    System.out.println("SERVER:"+input.nextLine());

                System.out.print("CLIENT:");
            }

        }catch(IOException e){
            e.printStackTrace();
        }finally{
            //關閉資源
            try{
                server.close();
                output.close();
                input.close();
                keyboard.close();
            }catch(IOException e){
                e.printStackTrace();
            }
        }

    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        test1();
    }

}