一、基本原理

Socket通信

Socket通信模型

ServerSocket的构造方法

服务器端创建的步骤

客户端创建的步骤

二、实际运行

服务器代码：

public static void main(String[] args) {
        try {
            //1、创建ServerSocket，绑定端口
            ServerSocket serverSocket=new ServerSocket(8888);
            System.out.println("服务器已经启动，等待连接。。。。");
            //2、等待客户机的连接
            Socket socket=serverSocket.accept();
            //3、创建输入流，接收客户端传来的消息
            InputStream inputStream=socket.getInputStream();
            BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream));
            String inString=null;
            while((inString=bufferedReader.readLine())!=null){//循环读取
                System.out.println("客户端说："+inString);
            }
            socket.shutdownInput();
            
            //4、创建输出流，给客户端返回响应的消息
            OutputStream outputStream=socket.getOutputStream();
            PrintWriter printWriter=new PrintWriter(outputStream);
            printWriter.write("欢迎您！");
            printWriter.flush();
            socket.shutdownOutput();
            
            //5、依次关闭
            printWriter.close();
            outputStream.close();
            bufferedReader.close();
            inputStream.close();
            socket.close();
            serverSocket.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   
    }

客户端代码：

public static void main(String[] args) {
       try {
           //1、创建客户端Socket,并且绑定IP地址和端口号
           Socket socket=new Socket("localhost",8888);
           
           //2、创建输出流，向服务器发送消息
           OutputStream outputStream=socket.getOutputStream();//字节输出流
           PrintWriter printWriter=new PrintWriter(outputStream);//变成打印流
           printWriter.write("用户名：Simon_Deng,密码：123456");
           System.out.println("已经信息发送给服务器！");
           printWriter.flush();                          //很重要，一定要写，否则消息发布出去
           socket.shutdownOutput();                      //关闭输出流
           
           //3、接收服务器返回的消息
           InputStream inputStream=socket.getInputStream();
           BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream));
           String infoString=null;
           while((infoString=bufferedReader.readLine())!=null){//循环读取
               System.out.println("接收到服务器信息："+infoString);
           }
           
           //4、依次关闭
           socket.shutdownInput();
           bufferedReader.close();
           inputStream.close();
           printWriter.close();
           outputStream.close();
           socket.close();
       } catch (UnknownHostException e) {
           e.printStackTrace();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

服务器运行截图

客户端截图

三、多线程通话

要实现多线程，只需改服务器即可，客户端代码不变

要新建ServerThread类继承Thread类

ServerThread代码：

public class ServerThread extends Thread{
    Socket socket=null;
    InputStream inputStream=null;
    OutputStream outputStream=null;
    BufferedReader bufferedReader=null;
    String info=null;
    PrintWriter printWriter=null;
    
    public ServerThread(Socket socket){
        this.socket=socket;
    }
    
    public void run(){
        try {
            inputStream=socket.getInputStream();
            bufferedReader=new BufferedReader(new InputStreamReader(inputStream));
            while((info=bufferedReader.readLine())!=null){
                System.out.println("我是服务器，客户端说："+info);
            }
            outputStream=socket.getOutputStream();
            printWriter=new PrintWriter(outputStream);
            printWriter.write("欢迎你！");
            printWriter.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
                try {
                    if(printWriter!=null)
                        printWriter.close();
                    if(outputStream!=null)
                        outputStream.close();
                    if(bufferedReader!=null)
                        bufferedReader.close();
                    if(inputStream!=null)
                        inputStream.close();
                    if(socket!=null)
                        socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }
    }
}

服务器代码：

public static void main(String[] args) {
        try {
            int count=0;
            ServerSocket serverSocket=new ServerSocket(8888);
            Socket socket=null;
            System.out.println("服务器正在等待连接.....");
            while(true){
                socket=serverSocket.accept();
                ServerThread serverThread=new ServerThread(socket);
                serverThread.start();   
                count++;
                System.out.println("客户机编号："+count+"已经连接！");
                InetAddress address=socket.getInetAddress();
                System.out.println("当前客户端ip地址为"+address.getHostAddress());
            }   
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

服务器运行截图