网络编程

网络编程

1.1、概述

1.2、网络信的要素

如何实现网络的通信

通信双方的地址:

  • ip
  • 端口

规则:网络通信的的协议

http TCP/IP

小结:

1.网络编程中有两个主要的问题

  • 如何准确的定位到网络上的一台或者多台主机
  • 找到主机之后如何进行通信

2.网络编程中的要素

  • IP和端口号 IP
  • 网络通信协议 UDP和TCP

3.万物皆对象

1.3、IP

IP地址:InetAddress

  • 唯一定位一台网络上的计算机

  • 127.0.0.1:本机localhost

  • ip地址的分类

  • IP地址分类

    • ipv4/ipv6
      • 四个字节 127.0.0.1 (localhost)
      • ipv6 fe80::2d79:960:796f:7dc0%6 128位 8个无符号整数
  • 公网(互联网)-私网(局域网)

    • 192.168.*.
  • 域名:记忆IP问题

package com.kuang.lesson01;

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

//测试IP
public class TestInetAddress {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            InetAddress inetAddress4 = InetAddress.getLocalHost();
            System.out.println(inetAddress4);
            //查询网站IP地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);

            //常用方法
            System.out.println(inetAddress2.getAddress());
            System.out.println(inetAddress2.getHostAddress());//IP
            System.out.println(inetAddress2.getCanonicalHostName());//规范的名字
            System.out.println(inetAddress2.getHostName());//域名

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

1.4、端口

端口表示计算机上的一个程序的进程

  • 不同的进程有不同的端口号!用来区别软件
  • 被规定0~65535
  • TCP,UDP
  • 端口分类
    • 公有端口:0~1023
    • HTTPS:443
    • FTP:21
    • Telent:23
    • HTTP:80
  • 程序注册端口:1024~49151,分配用户或者程序
    • Tomcat:8080
    • MySQL:3306
    • Oracle:1521
  • 动态、私有:49152~65535
netstat -ano #查找所有的端口
netstat -ano|findstr "59000" #查找指定的端口
tasklist|findstr "8696" #查看指定端口的进程
    
package com.kuang.lesson01;

import java.net.InetSocketAddress;

public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress inetSocketAddress1 = new InetSocketAddress("127.0.0.1",8080);
        System.out.println(inetSocketAddress1);
        InetSocketAddress inetSocketAddress2 = new InetSocketAddress("localhost",8080);
        System.out.println(inetSocketAddress2);

        System.out.println(inetSocketAddress1.getAddress());
        System.out.println(inetSocketAddress1.getHostName());//地址
        System.out.println(inetSocketAddress1.getPort());//端口
    }
}

1.5、通信协议

协议:约定

网络通信协议:速率,传输码率,代码结构,传输控制.....

大事化小:分层

TCP/IP协议簇

重要:

  • TCP:用户传输协议
  • UDP:用户数据报协议

出名的协议

  • TCP:
  • IP:网络互连协议

TCP udp 对比

TCP:打电话

  • 连接稳定

  • 三次握手 四次挥手

    最少需要三次,保持稳定连接
    A:你愁啥?
    B:瞅你咋地?
    C:干一场!
        
    A:我要走了
    B:我真的要走了
    B:你真的真的要走了吗?
    A:我真的真的要走了!
    
  • 客户端、服务端

  • 传输完成,释放连接,效率低

UDP:发信息

  • 不连接、不稳定
  • 客户端、服务端:没有明确的界限
  • 不管有没有准备好,都可以发给你
  • 导弹
  • DDOS:洪水攻击!(饱和攻击)

1.6、TCP

客户端

1.连接服务器Socket

2.发送消息

package com.kuang.lesson02;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.charset.StandardCharsets;

//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1.要知道服务器的地址 端口号
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //创建一个socket连接
            socket = new Socket(serverIP,port);
            //发送消息 IO流
            os = socket.getOutputStream();
            os.write("你好,欢迎学习狂神学java".getBytes(StandardCharsets.UTF_8)) ;


        } 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();
                }
            }

        }
    }
}

服务器

1.建立服务的端口 ServerSocket

2.等待用户的连接 accept

3.接受用的消息

package com.kuang.lesson02;

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

//服务端
public class TcpServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;


        try {
            //我得有一个地址
            serverSocket = new ServerSocket(9999);
            //等待客户端连接过来
            while (true){
                socket = serverSocket.accept();
                //读取客户端的消息
                is = socket.getInputStream();
                //管道流
                baos = new ByteArrayOutputStream();
                byte[] buffer = new byte[1024];
                int len;
                while((len=is.read(buffer))!=-1){
                    baos.write(buffer,0,len);//一直往管道外输出
                }
                System.out.println(baos.toString());

            }



        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭资源
            if(baos!=null){
                try {
                    baos.close();//后开先关
                } catch (IOException e) {
                    e.printStackTrace();

                }
            }
            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();
                }
            }

        }
    }
}

文件上传

package com.kuang.lesson02;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;

/**
 * 客户端接收文件
 */
public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //1.创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //2.监听客户端的连接
        Socket socket = serverSocket.accept();//阻塞式监听,会一直等待客户端连接
        //3.获取输入流
        InputStream is = socket.getInputStream();
        //4.文件输出
        FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }

        //通知客户我接受完毕了
        OutputStream os = socket.getOutputStream();
        os.write("我接受完毕了,你可以断开了".getBytes());

        //关闭资源
        os.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}
package com.kuang.lesson02;

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception {
        //创建一个Socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //创建一个输出流
        OutputStream os = socket.getOutputStream();

        //读取文件
        FileInputStream fis = new FileInputStream(new File("peng.jpg"));
        //写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len=fis.read(buffer))!=-1){
            os.write(buffer,0,len);
        }

        //通知服务器,我已经传输完了
        socket.shutdownOutput();

        //确定服务器接受完毕,才能断开连接
        InputStream is = socket.getInputStream();
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        int len2;
        byte[] buffer2 = new byte[10240];
        while((len2=is.read(buffer2))!=-1){
            bos.write(buffer2,0,len2);
        }
        System.out.println(bos.toString());


        //关闭资源
        bos.close();
        is.close();
        fis.close();
        os.close();
        socket.close();
    }
}

Tomcat

服务端

  • 自定义
  • Tomcat服务器 S : Java后台开发

客户端

  • 自定义

  • 浏览器 B

1.7、UDP

发短信:不用连接,需要知道对方的地址!


发送端

package com.kuang.lesson03;

import com.sun.xml.internal.ws.api.model.wsdl.WSDLOutput;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一个socket
        DatagramSocket socket = new DatagramSocket();
        //2.建个包
        String mes = "你好呀! 服务器";

        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        //数据、数据的长度起始、发送的对象
        DatagramPacket packet = new DatagramPacket(mes.getBytes(),0,mes.getBytes().length,localhost,port);

        //3.发个包
        socket.send(packet);

        //4.关闭流
        socket.close();
    }
}

接受端

package com.kuang.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//还是要等待客户端的连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接受数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);

        socket.receive(packet);//阻塞接受
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));

        socket.close();
    }
}

循环发送消息

package com.kuang.chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;

public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);


        while (true){
            //准备数据: 控制台读取 System.in
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            String data = reader.readLine();
            DatagramPacket packet = new DatagramPacket(data.getBytes(),data.getBytes().length,new InetSocketAddress("localhost",6666));

            socket.send(packet);
            if(data.equals("bye")){//本地退出
                break;
            }

        }



        socket.close();
    }
}

循环接收消息

package com.kuang.chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.util.Scanner;

public class UDPReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);

        //BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));


        while(true){
            //准备接受包裹
            byte[] container = new byte[1024];//目前不管发送数据大小输出的都是1024字节
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接收包裹

            //断开连接  bye
            byte[] data = packet.getData();

            String receiveData = new String(data,0, data.length);
            System.out.println(receiveData);

            if(receiveData.equals("bye")){
                break;
            }
        }

        socket.close();
    }
}

在线咨询:两个人都可以是发送方,也都可以是接受方

package com.kuang.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}
package com.kuang.chat;

public class TalkStudent {
    public static void main(String[] args) {
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师")).start();
    }
}
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package com.kuang.chat;

public class TalkStudent {
    public TalkStudent() {
    }

    public static void main(String[] args) {
        (new Thread(new TalkSend(7777, "localhost", 9999))).start();
        (new Thread(new TalkReceive(8888, "老师"))).start();
    }
}
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package com.kuang.chat;

public class TalkTeacher {
    public TalkTeacher() {
    }

    public static void main(String[] args) {
        (new Thread(new TalkSend(5555, "localhost", 8888))).start();
        (new Thread(new TalkReceive(9999, "学生"))).start();
    }
}

1.8URL

https://www.baidu.com/

统一资源定位符:定位资源,定位互联网上的某一个资源

DNS 域名解析 把域名变为IP


协议://IP地址(就是域名):端口/项目名/资源

下载网上资源

package com.kuang.lesson04;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

public class URLDemo01 {
    public static void main(String[] args) throws IOException {
        //连接地址
        URL url = new URL("https://s1.music.126.net/style/favicon.ico?v20180823");
        //连接到这个资源http
        HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();

        InputStream inputStream = urlConnection.getInputStream();
        FileOutputStream fos = new FileOutputStream("new.ico");

        byte[] buffer = new byte[1024];
        int len;
        while ((len=inputStream.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }

        fos.close();
        inputStream.close();
        urlConnection.disconnect();//断开连接
    }
}
posted @ 2021-10-07 17:18  肖寒*  阅读(72)  评论(0编辑  收藏  举报