[网络协议]网络编程讲解

概述

• 网络编程：TCP/UDP，C/S架构。网页编程：JavaWeb，B/S架构
• 智能汽车技术已经非常成熟。存在伦理问题

网络通信要素

• ip+端口号：192.168.1.1:5900
• 在C:\windows\system32内才可以ping baidu.com。或者把C:\windows\system32增加到系统变量中

IP

• 127.0.0.1：本机localhost

package com.adair.lesson1;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class TestInetAddress {
    public static void main(String[] args) {
        try {
            //查询本地主机
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);//   /127.0.0.1

            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);//     localhost/127.0.0.1

            InetAddress inetAddress4 = InetAddress.getLocalHost();
            System.out.println(inetAddress4);//        DESKTOP-Adair/192.168.1.2

            //查询百度ip
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2); //        www.baidu.com/39.156.66.14

            System.out.println(inetAddress2.getAddress());      //[B@74a14482
            System.out.println(inetAddress2.getCanonicalHostName());// 39.156.66.14
            System.out.println(inetAddress2.getHostAddress());//    39.156.66.14
            System.out.println(inetAddress2.getHostName());//       www.baidu.com


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

端口port

• 表示一台电脑上的一个程序的进程，不同的进程有不同的端口号。0~65535
• TCP/UDP ：2*65535。TCP:80 &&UDP:80，同一类型端口不可相同
• 端口分类
  • 服务器端：公有端口0~1023。HTTP:80 HTTPS:443 FTP:21
  • 服务器端：程序注册端口1024~49151。Tomcat8080 MySQL3306 Oracle1521
  • 客户端：端口号49152~65535：暂时的动态私有，不可用

netstat -ano   //查看所有端口
netstat -ano|findstr "10809"	//查看指定端口，先查询再带入
tasklist|findstr "8232"		//查看指定端口的进程

• C:\Windows\System32\drivers\etc下的hosts可以查看本机的配置

package com.adair.lesson1;

import java.net.InetSocketAddress;

public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost", 8080);
        System.out.println(socketAddress);  //      /127.0.0.1:8080
        System.out.println(socketAddress2);  //      localhost/127.0.0.1:8080

        System.out.println(socketAddress.getAddress());//       /127.0.0.1
        System.out.println(socketAddress.getHostName());//      127.0.0.1
        System.out.println(socketAddress.getPort());//8080
    }
}

通信协议

• TCP：类与打电话
  • 三次握手、四次挥手
• UDP：类与发短信
  • DDOS：洪水攻击

TCP

客户端

• 连接服务器Socket
• 发送消息

服务器

• 建立服务的端口ServerSocket
• 等待用户的连接accept
• 接受用户的消息

package com.adair.lesson2;

import com.sun.xml.internal.messaging.saaj.util.ByteOutputStream;

import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        ByteOutputStream baos = null;
        InputStream is = null;
        try {
            //需要有个地址
            serverSocket = new ServerSocket(9999);

            while(true){
                //等待客户端连接
                socket = serverSocket.accept();
                //读取客户端消息
                is = socket.getInputStream();


                //管道流
                baos = new ByteOutputStream();
                byte[] buffer = new byte[1024];
                int len;
                while((len = is.read(buffer))!=-1){
                    baos.write(buffer,0,len);
                }
                System.out.println(baos.toString());
            }

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(baos != null){
                baos.close();
            }
            if(is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(serverSocket != null){
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

--------------------------------------
package com.adair.lesson2;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class TcpClientDemo01 {
    public static void main(String[] args) {
        OutputStream os = null;
        Socket socket  = null;
        try {
            //创建地址和端口
            InetAddress serveIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //创建socket连接
            socket = new Socket(serveIP,port);
            //发送消息  IO流
            os = socket.getOutputStream();
            os.write("我在永远在路上".getBytes());


        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if(os!=null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}