网络编程基础

网络编程

1.1概述

信件📃

packet：对方的信息，对方的名称，对方的地址，自己的地址

打电话： --连接--接听--通话-- TCP

发短信：--发送了就完事--接收-- UDP

计算机网络

计算机网络系统就是利用通信设备和线路将地理位置不同、功能独立的多个计算机系统互联起来，以功能完善的网络软件实现网络中资源共享和信息传递的系统。通过计算机的互联，实现计算机之间的通信，从而实现计算机系统之间的信息、软件和设备资源的共享以及协同工作等功能，其本质特征在于提供计算机之间的各类资源的高度共享，实现便捷地交流信息和交换思想。

网络编程的目的：

传播交流信息

想要达到的效果

1.准确定位网络上的一台主机 192.168.16.124 : port，定位到计算机上的某个资源

2.找到这个主机，如何传输数据

Javaweb 网页编程 B/S

网络编程： TCP/IP C/S

1.2网络通信的要素

如何实现网络通信？

通信双方地址

IP
端口号

规则：网络通讯协议

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
ip分类
- 公网-私网
- ipv4/ipv6
域名

//测试IP
public class Test {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress address1 = InetAddress.getByName("127.0.0.1");
            System.out.println(address1);
            InetAddress address2 = InetAddress.getByName("localhost");
            System.out.println(address2);
            InetAddress address3 = InetAddress.getLocalHost();
            System.out.println(address3);
            //查询网站地址
            InetAddress address4 = InetAddress.getByName("www.baidu.com");
            System.out.println(address4);

            //常用方法
            System.out.println(address4.getAddress());
            System.out.println(address4.getCanonicalHostName());
            System.out.println(address4.getHostAddress());
            System.out.println(address4.getHostName());
        } 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！用来区分软件
被规定0~65535
TCP,UDP:65535*2
端口分类
- 共用端口 0~1023
  - HTTP：80
  - HTTPs：443
  - FTP: 21
  - Telent: 23
- 程序注册端口：1024~49151
  - Tomcat：8080
  - MySql ：3306
- 动态，私有端口：49152~65535

public class TestInetSocketAdderss {
    public static void main(String[] args) {
        InetSocketAddress socketAddress1 = new InetSocketAddress("127.0.0.1",8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost",8080);
        System.out.println(socketAddress1);
        System.out.println(socketAddress2);
        System.out.println(socketAddress1.getAddress());
        System.out.println(socketAddress1.getHostName());
        System.out.println(socketAddress1.getHostString());
        System.out.println(socketAddress1.getPort());
    }

1.5 通讯协议

重要：

TCP：用户传输协议

打电话

连接，稳定
三次握手，四次挥手

三次握手：至少需要三次，保持稳定连接
A:你瞅啥？
B:瞅你咋地？
A:干一场！

A:我要走了!
B：你真的要走了吗？
A：你真的真的要走了吗？
A：我真的要走了！

客户端，服务端
传输完成，释放连接

UDP：用户数据报协议
- 发短信
  - 不连接，不稳定
  - 不管有没有准备好，都可以发给你
  - 洪泛传播

1.6 TCP

客户端

1.连接服务器socket

2.发送消息

服务器

1.建立服务端口ServerSocket

2.等待用户连接accept

3.接收用户消息

数据传输

客户端代码
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;

//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1.知道服务器的地址
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            //2.端口号
            int port = 9999;
            //3.创建一个socket连接
            socket = new Socket(serverIP,port);
            //4.IO流 发送消息
            os = socket.getOutputStream();
            os.write("好好学习".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();
                }
            }
        }
    }
}

服务端代码
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 {
            //1.我得有一个地址
            serverSocket = new ServerSocket(9999);

            while (true) {
                //等到客户端连接过来
                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);
                }
                System.out.println(baos.toString());
            }

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

客户端
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socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9998);
        //创建一个输出流
        OutputStream os = socket.getOutputStream();
        //文件流,读取文件
        FileInputStream fis = new FileInputStream(new File("NatureCao.txt"));
        //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，出书完成
        socket.shutdownOutput();

        //确定服务端接收完毕
        InputStream is = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while((len2=is.read(buffer2))!=-1){
            baos.write(buffer2,0,len2);
        }
        System.out.println(baos.toString());

        baos.close();
        is.close();
        fis.close();
        os.close();
        socket.close();
    }
}

服务器
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //创建服务
        ServerSocket serverSocket = new ServerSocket(9998);
        //监听客户端连接
        Socket socket = serverSocket.accept();
        //获取输入流
        InputStream is = socket.getInputStream();
        //文件输出
        FileOutputStream fos = new FileOutputStream("receive.txt");
        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("接收完毕".getBytes());

        os.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

1.7 UDP

发短信，需要知道对方的地址

发送端
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //建立一个socket
        DatagramSocket socket = new DatagramSocket();
        String msg = "hello";

        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        //建立一个包
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
        //发送包
        socket.send(packet);
        socket.close();
    }
}

接收端
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);

        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
        socket.receive(packet);
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        socket.close();
    }
}

两个人聊天：

首先实现循环发送接收

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

public class UdpSenderDemo01 {
    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();
    }
}

接收者
package com.miar.chat;

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

public class UdpReceiverDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);

        while(true){
            //准备接受数据包
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet); //阻塞式接收
            //断开连接
            byte[] data = packet.getData();
            String receiveData = new String(data,0,data.length);
            System.out.println(receiveData);
            if (receiveData.equals("bye")){
                break;
            }

        }

//        socket.send();
        socket.close();
    }
}

再实现两个人相互发送接收：多线程

实现Runnable接口
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

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

    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        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) {
            String data = null;
            try {
                data = reader.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            byte[] datas = data.getBytes();
            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));
            try {
                socket.send(packet);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (data.equals("bye"))
                break;
        }
        socket.close();
    }
}

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

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 (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while(true){
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            try {
                socket.receive(packet);
            } catch (IOException e) {
                e.printStackTrace();
            }
            byte[] data = packet.getData();
            String receiveData = new String(data,0,data.length);
            System.out.println(msgFrom+":"+receiveData);

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

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();
    }
}

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();
    }
}

1.8 URL

https://www.baidu.com/

统一资源定位符：定位互联网上的某一个资源

协议://ip地址:端口/项目名/资源

posted @ 2021-05-18 20:01 Miarlee 阅读(59) 评论(0) 收藏举报

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