网络编程

2023-11-01 22:09:22

网络编程

1.1网络通信的要素

如何实现网络通信？

通信双方的地址：

  • ip
  • 端口号

规则：网络通信的协议

TCP/IP参考模型：

网络编程

小结：

  1. 网络编程中两个主要的问题

    • 如何准确的定位到网络上的一台主机或者多台主机
    • 如何进行通信

  2. 网络编程要素

    • Ip和端口号 IP
    • 网络通信协议 UDP TCP

  3. 万物皆对象

1.2 IP

ip地址：InetAddress

  • 唯一定位一台网络计算机

  • 127.0.0.1：本地localhost

  • ip地址的分类

    • ipv4、ipv6
    • 公网-私网

  • 域名：记忆IP问题！

    • IP

        public static void main(String[] args) throws UnknownHostException {
        //查询本机地址
        InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
        System.out.println(inetAddress);
        InetAddress localhost = InetAddress.getByName("localhost");
        System.out.println(localhost);
        System.out.println(InetAddress.getLocalHost());

        //查询网站ip地址
        InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");
        System.out.println(inetAddress1);
        //常用方法
        System.out.println(inetAddress1.getAddress());
        System.out.println(inetAddress1.getCanonicalHostName()); //规范的名字
        System.out.println(inetAddress1.getHostAddress());   //ip
        System.out.println(inetAddress1.getHostName());    //域名，或者是自己电脑的名字
    }

1.3 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！用来区分软件

  • 被规定0~65535

  • TCP UDP:65535*2 tcp 80 udp 80 单个协议下，端口号不能冲突

  • 端口分类

    • 公有端口0~1023

      • Http：80
      • https：443
      • ftp：21
      • telent：23

    • 程序注册端口：1024~49151，分配给用户或者程序

      • Tomcat：8080
      • Mysql：3306
      • Oracle：1521

    • 动态、私有：49152~65535

      netstat -ano #查看所有的端口
netstat -ano|findstr "5900" #查看置顶的端口
tasklist|findstr "8696" #查看此端口的进程
Ctrl + shift + Esc #打开任务管理 

       public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1",8080);
        InetSocketAddress socketAddress1 = new InetSocketAddress("localhost", 8080);
        System.out.println(socketAddress);
        System.out.println(socketAddress1);

        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getHostName()); //host
        System.out.println(socketAddress.getPort()); //端口
    }

1.4 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.....

问题：非常复杂

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：网络互联协议

TCP 和 UDP对比

1.5 TCP

客户端

  1. 链接服务器Socket

  2. 发送消息

    public static void main(String[] args) {
        OutputStream outputStream=null;
        Socket socket =null;
        try {
            //1.知道服务器地址，端口号
            InetAddress serverIp = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2.创建一个socket链接
            socket = new Socket(serverIp, port);
            //发送消息 IO流
            outputStream = socket.getOutputStream();

            outputStream.write("你好，欢迎学习Java".getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (outputStream!=null){
                try {
                    outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

服务器

  1. 建立服务器端口ServerSocket
  2. 等待用户的链接 accept
  3. 接收用户消息
public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket =null;
        InputStream inputStream =null;
        ByteArrayOutputStream byteArrayOutputStream =null;
        try {
            //1.我有一个地址
             serverSocket = new ServerSocket(9999);
             while(true){   //用于一直结束客户端消息
                 //2. 等待客户端链接
                 socket = serverSocket.accept();
                 //3.读取客户端的消息
                 inputStream = socket.getInputStream();
                 //管道流
                 byteArrayOutputStream = new ByteArrayOutputStream();
                 byte[] buffer = new byte[1024];
                 int len;
                 while ((len=inputStream.read(buffer))!=-1){
                     byteArrayOutputStream.write(buffer,0,len);
                 }
                 System.out.println(byteArrayOutputStream.toString());
             }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭资源
            if (byteArrayOutputStream!=null){
                try {
                    byteArrayOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
           if (inputStream!=null){
               try {
                   inputStream.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

  1. 客户端
 public static void main(String[] args) throws Exception {
        //1.创建一个socket链接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //2.创建一个输出流
        OutputStream outputStream = socket.getOutputStream();
        //3.读取文件
        FileInputStream fis = new FileInputStream(new File("15.jpg"));
        //4.写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len=fis.read(buffer))!=-1){
            outputStream.write(buffer,0,len);
        }
        //通知服务器，已经传输完成
        socket.shutdownOutput();
        //确定服务器接收完毕，才能断开链接
        InputStream inputStream = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len2=inputStream.read(buffer2))!=-1) {
            baos.write(buffer2,0,len2);
        }
        System.out.println(baos.toString());
        //5.关闭资源
        baos.close();
        inputStream.close();
        fis.close();
        outputStream.close();
        socket.close();
    }
  1. 服务器端
 public static void main(String[] args) throws Exception {
        //1.创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //2.监听客户端链接
        Socket socket = serverSocket.accept();//阻塞式监听，一直当地啊客户端链接
        //3.获取输入流
        InputStream is = socket.getInputStream();

        //4.文件输出
        FileOutputStream fos = new FileOutputStream(new File("a.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        //通知客户端接收完毕
        OutputStream os = socket.getOutputStream();
        os.write("我接受完毕了，可以断开了".getBytes());
        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }

Tomcat

服务端

  • 自定义
  • Tomcat服务器

客户端

  • 自定义 C
  • 浏览器 B

1.6 UDP

发短息：不用链接，需要知道对方的地址！

发送消息

 public static void main(String[] args) throws Exception {
        //1.建立一个socket
        DatagramSocket socket = new DatagramSocket();
        //2.建个包
        String msg = "你好呀，服务器";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port =9090;
        //数据，数据长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
        //3.发送包
        socket.send(packet);
        //关闭流
        socket.close();
    }

接收消息

 public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接收数据
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
        socket.receive(packet);//阻塞式接收消息
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭链接
        socket.close();
    }

循环发送消息

public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        //准备数据：控制台读取 System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true){
            String data = reader.readLine();
            byte[] datas = data.getBytes();
            DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));
            socket.send(packet);
            if (data.equals("bye")){
                break;
            }
        }
        socket.close();
    }

循环接收消息

public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        //准备接收包裹

        while (true){
           byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接收包裹
            //断开链接 bye
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, data.length);
            if (receiveData.equals("bye")){
                break;
            }
            System.out.println(receiveData);
        }
       socket.close();
    }

聊天

  1. 发送方
package com.yuwei.chat;

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

public class TalkSend implements Runnable{
    private DatagramSocket socket = null;
    private BufferedReader reader = null;

    private String toIp;
    private int toPort;


    public TalkSend(int fromPort, String toIp, int toPort) {
        this.toIp = toIp;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(fromPort);
            reader=new BufferedReader(new InputStreamReader(System.in));
        }catch (Exception e){
            e.printStackTrace();
        }

    }

    @Override
    public void run() {
        while (true){
            try {
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new
                        DatagramPacket(datas,0,datas.length,
                        new InetSocketAddress(this.toIp,this.toPort));
                //4. 发送包裹send
                socket.send(packet);
                //退出判断
                if (data.equals("bye")){
                    break;
                }
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        //5. 释放资源
        socket.close();
    }
}
  1. 接收方
package com.yuwei.chat;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class TalkReceive implements Runnable {
    DatagramSocket socket =null;
    private int port;
    private String msgFrom;
    public TalkReceive(int port,String msgFrom) {
        this.port = port;
        this.msgFrom = msgFrom;
        try {
            socket = new DatagramSocket(port);
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true){
            try{
                byte[] container =new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet);//阻塞式接收
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, data.length);
                System.out.println(msgFrom + ": " + receiveData);
                //断开链接 bye
                if (receiveData.equals("bye")){
                    break;
                }

            }catch (Exception e){
                e.printStackTrace();
            }
        }
        socket.close();
    }
}
  1. 学生线程
package com.yuwei.chat;

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师")).start();
    }
}
  1. 教师线程
package com.yuwei.chat;

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

1.7 URL

统一资源定位符：定位资源的，定位互联网上的某一个资源

协议：// ip地址：端口号/项目名/资源

package com.kuang.lesson6;
import java.net.MalformedURLException;
import java.net.URL;
public class URLDemo01 {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://localhost:8080/helloworld/index.jsp?
username=kuangshen&password=123");
            System.out.println(url.getProtocol()); //获取URL的协议名
            System.out.println(url.getHost());     //获取URL的主机名
            System.out.println(url.getPort());     //获取URL的端口号
            System.out.println(url.getPath());     //获取URL的文件路径
            System.out.println(url.getFile());     //获取URL的文件名
            System.out.println(url.getQuery());    //获取URL的查询名
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }
}

下载tomcat下的文件

首先需要在tomcat中放入一个资源文件！

package com.kuang.lesson6;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class URLDemo02 {
    public static void main(String[] args) {
        try {
            //1. 定位到服务器端的资源
            URL url = new URL("http://localhost:8080/helloworld/qinjiang.jpg");
            //2. 链接这个资源 HTTP
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            //3. 获取输入流
            InputStream is = connection.getInputStream();
            //4. 写出文件
            FileOutputStream fos = new FileOutputStream("qinjiang2.jpg");
            byte[] buffer = new byte[1024];
            int len;
            while ((len=is.read(buffer))!=-1){
                fos.write(buffer,0,len); //写出这个数据
            }
            //关闭资源
            fos.close();
            is.close();
            connection.disconnect(); //断开连接
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

网络编程

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