阿小冷学计算机（5）

2023-12-12 18:01:46

网络编程

注：来自b站up主遇见狂神说的java系列
本人自学记录

概述

目的：传播交流信息，数据交换，通信

想要达到这个效果需要什么：

1、如何准确的定位网络上的一台主机和端口
2、找到了这个主机，如何传输数据呢？？

网络通信的要素

如何实现网络的通信?
通信双方的地址：

1、ip
2、端口号

规则：网络通信的协议
TCP/IP参考模型
小结：
1、网络编程中有两个主要问题

如何准确的定位到网络上的一台或者多台主机
找到主机之后进行通信
2、网络编程中的要素
IP号和端口号
网络通信协议
3、万物皆对象

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
– ipv4/ipv6
— ipv4 127.0.0.1， 4个字节组成，42亿；
— ipv6 fe80::713a:22cc:2566:3e3a%15 ， 128位。8个无符号整数！
公网（互联网）-私网（局域网）
–ABCD类地址
– 192.168.xx.xx，专门给*内部使用的
域名：记忆ip问题

package com.axiaoleng;

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 byName1 = InetAddress.getByName("127.0.0.1");
            System.out.println(byName1);
            InetAddress byName2 = InetAddress.getByName("localhost");
            System.out.println(byName2);
            InetAddress byName3 = InetAddress.getLocalHost();
            System.out.println(byName3);


            //常用方法
            System.out.println(byName2.getAddress());
            System.out.println(byName2.getCanonicalHostName()); //规范的名字
            System.out.println(byName2.getHostAddress());//ip
            System.out.println(byName2.getHostName());//域名或者本机电脑的名字

            //查询网站ip地址
            InetAddress byName4 = InetAddress.getByName("www.baidu.com");
            System.out.println(byName4);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

端口

端口表示计算机上一个程序的进程

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,发给用户或者程序
– Tomcat : 8080
– MySQL: 3306
– Oracle: 1521
动态、私有：49152~65535

netstat -ano  #查看所有端口
netstat -ano|findstr "5900" #查看指定的端口
tasklist|findstr "" #查看指定端口的进程

package com.axiaoleng;

import java.net.InetSocketAddress;

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

        System.out.println(inetSocketAddress.getAddress());
        System.out.println(inetSocketAddress.getHostName());
        System.out.println(inetSocketAddress.getPort());
    }
}

通信协议

协议：约定，就好比我们现在说的普通话。
网络通信协议：速率、传输码率、代码结构、传输控制。。。
TCP/IP协议簇：实际上是一组协议
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与UDP的对比
TCP：打电话

连接，稳定
三次握手四次挥手
客户端、服务段
传输完成，释放连接，效率低

UDP:发短信

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
DDOS：洪水攻击！

TCP

客户端

1、连接服务器（知道服务器的地址和端口）
2、创建一个socket连接
3、发送消息

package com.axiaoleng;

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

//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;

            //2、创建一个socket连接
            socket = new Socket(serverIP,port);

            //3、发送消息 io流
            os = socket.getOutputStream();
            os.write("你好，欢迎学习狂神说Java".getBytes());


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

服务端

1、建立服务的端口 ServerSocket
2、等待用户的连接 accept
3、接受用户信息

package com.axiaoleng;

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、必须有一个地址
            serverSocket = new ServerSocket(9999);
            while(true) {
                //2、等待客户端连接过来
                socket = serverSocket.accept();
                //3、读取客户端的消息
                is = socket.getInputStream();

                //4、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

package com.axiaoleng;

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 IOException {
        //1、创建一个Socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);

        //2、创建一个输出流
        OutputStream os = socket.getOutputStream();

        //3、读取文件
        FileInputStream fis = new FileInputStream(new File("1.png"));

        //4、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，传输停止
        socket.shutdownOutput();



        //确定服务器接收完毕，才能断开连接
        InputStream in = socket.getInputStream();
        //String byte[]
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] buffer2 = new byte[1024];
        int len2;
        while((len2=in.read(buffer2))!=-1){
            baos.write(buffer2,0,len2);
        }

        System.out.println(baos.toString());

        //5、关闭资源
        baos.close();
        in.close();

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

服务端

package com.axiaoleng;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo02 {
    public static void main(String[] args) throws IOException {
        //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("receive.png");
        byte[] buffer = new byte[1024];
        int len;
        while((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }

        //通知客户端我接收完毕了
        OutputStream os = socket.getOutputStream();
        os.write("我接收完毕了，你可以断开了".getBytes());

        //关闭资源
        os.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

UDP

发短信：不用连接，需要知道对方的地址

发送消息

package com.axiaoleng;

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 msg="你好啊，服务器";
        InetAddress localhost = InetAddress.getByName("localhost");
        int port=9090;

        //数据，数据的长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);

        //3、发送包
        socket.send(packet);

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

接收端

package com.axiaoleng;


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

//还是要等待客户端的链接
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);  //阻塞接收

        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));

        //关闭连接
        socket.close();
    }

}

循环发送消息

package com.axiaoleng;

import java.io.BufferedReader;
import java.io.InputStream;
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);

        //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

package com.axiaoleng;

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

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);

        while(true){

            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            socket.receive(packet); //阻塞式接收包裹

            //断开连接
            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，也可以接收方

package com.axiaoleng;

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{

    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) {
            try{
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));

                socket.send(packet);
                if(data.equals("bye")){
                    break;
                }
            }catch(Exception e){
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package com.axiaoleng;

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{
                //准备接收包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet); //阻塞式接收包裹

                //断开连接
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, data.length);
                System.out.println(msgFrom+":"+receiveData);

                if(receiveData.equals("bye")){
                    break;
                }
            }catch(Exception e){
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package com.axiaoleng;

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();
    }
}

package com.axiaoleng;

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();
    }
}

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
包括：协议：//ip地址：端口/项目名/资源

package com.axiaoleng;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class UrlDown {
    public static void main(String[] args) throws Exception {
        //1、下载地址
        URL url = new URL("http://localhost:8080/qinjiang/SecurityFile.txt");

        //2、连接到这个资源 Http
       HttpURLConnection urlConnection=(HttpURLConnection) url.openConnection();

        InputStream inputStream = urlConnection.getInputStream();

        FileOutputStream fos = new FileOutputStream("SecurityFile.txt");

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

        fos.close();
        inputStream.close();
        urlConnection.disconnect();  //断开连接
    }
}

码农公寓

网络编程

概述

网络通信的要素

IP

端口

通信协议

TCP

文件上传

UDP

URL

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