package cn.sasa.TcpDemo;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.Socket;

//客户端

public class TCPSocketDemo {

    public static void main(String[] args) throws IOException {

        Socket socket = new Socket("127.0.0.1",8040);

        //传ip和端口号，直接和服务器建立连接，如果连接失败，就抛异常

        OutputStream output = socket.getOutputStream();

        output.write("hello".getBytes());//往服务器写

        //读取服务器发回的数据

        InputStream input = socket.getInputStream();

        byte[] buff = new byte[1024];

        int len = input.read(buff);

        System.out.println(new String(buff,0,len));

        socket.close();

    }

}

package cn.sasa.TcpDemo;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.ServerSocket;

import java.net.Socket;

//服务端

public class TCPServerSocketDemo {

    public static void main(String[] args) throws IOException {

        /**

         * java中的TCP和UDP的socket通信区别在于TCP通信区分服务器和客户端

         * TCP服务器：ServerSocket

         * TCP客户端：Socket

         *

         * 客户端向服务器发送请求

         * 服务器接收客户端请求，建立连接,，两者之间通过IO流传输

         * 客户端向服务器发数据 output.write

         * 服务器接收 input.read

         * 服务器响应客户端 output.write

         * 客户端接收服务器消息 input.read

         *

         * 服务器必须要获得客户端的套接字对象Socket,服务器需要知道是和谁的连接

         * Socket accept()

         */

        ServerSocket server = new ServerSocket(8040);

        Socket socket = server.accept();

        //获得输入流

        InputStream input = socket.getInputStream();

        byte[] buff = new byte[1024];

        int len = input.read(buff);

        System.out.println(new String(buff,0,len));

        //服务器向客户端发数据

        OutputStream output = socket.getOutputStream();

        output.write("received".getBytes());

        socket.close();

        server.close();

    }

}