JAVA网络编程实战（笔记）

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Frank___7 2022-02-22 11:02:12 博主文章分类：JAVA网络编程学习 ©著作权

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计算机网络简介

网络编程的目的：

无限电台。。。。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 ip地址192.168.16.124：端口，定位到这个计算机上的某个资源

2.找到了这个主机，如何传输数据

Javaweb：网页编程 B/s Brower/Server(浏览器/服务器)架构

网络编程：TCP/IP C/S Client/Server(客户端/服务器)

网络通信的要素

如何实现网络的通信？

通信双方地址：

IP
端口号
192.168.16.124：:5900
规则：网络通信的协议TCP/IP[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-3bCCN96B-1608736331564)(C:\Users\王东梁\AppData\Roaming\Typora\typora-user-images\image-20201223163659380.png)]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 tcp

万物皆对象

IP地址

ip地址：inteAddress 查看本地cmd ipconfig

唯一定位一台网络上计算机
127.0.0.1：本机localhost
ip地址的分类
package com.kuang.demo1; import java.net.InetAddress; import java.net.UnknownHostException; public class TestInetAddress { public static void main(String[] args) { try { InetAddress localHost = InetAddress.getLocalHost(); System.out.println(localHost); InetAddress[] inetAddress1 = InetAddress.getAllByName("127.0.0.1"); System.out.println(inetAddress1); System.out.println(InetAddress.getByName("localhost")); InetAddress inetAddress = InetAddress.getByName("www.baidu.com"); System.out.println(inetAddress); } catch (UnknownHostException e) { e.printStackTrace(); } } }

ipv4/Ipv6

ipv4 127.0.0.1 4个字节组成。 0~255 42亿个
ipv6 fe80::60f8:dddd:6bea:17a7%5 ，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,专门给组织内部使用的

端口

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etstat -ano #查看所有的窗口
netstat -ano|findstr"5900" #查看指定的端口
taskList|findstr "8696" #查看指定端口的进程
ctrl+shift+Esc

通信协议

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和UDP对比

TCP

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UDP

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TCP实现聊天

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package com.kuang.demo02;

import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpClientDemo01 {
    public static void main(String[] args) throws Exception {
        Socket socket=null;
        OutputStream os=null;
        try {
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port=9999;
            socket = new Socket(serverIP, port);
            os = socket.getOutputStream();
            os.write("asdfdasfdsa".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            os.close();
            socket.close();


        }


    }

}

package com.kuang.demo02;

import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServerDemo01 {
    public static void main(String[] args) throws Exception {
        ServerSocket serverSocket=null;
        Socket socket=null;
        InputStream is=null;
        ByteArrayOutputStream baos=null;
        //1.创建服务
        try {
            serverSocket = new ServerSocket(9999);
            //2.监听客户端的连接
            socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接
            //3.获取输入流
            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
            baos.close();
            is.close();
            socket.close();
            serverSocket.close();
        }
    }

}

TCP实现文件上传

package com.kuang.demo02;
import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //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);
        }
        //通客户端已经接受完了
        OutputStream outputStream = socket.getOutputStream();
        outputStream.write("我已经接收完了，可以断开了".getBytes());
        //5.关闭资源
        fis.close();
        os.close();
        socket.close();
    }
}

package com.kuang.demo02;
import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServerDemo01 {
    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.png"));
        byte[] buffer=new byte[1024];
        int len;
        while ((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

初始Tomacat

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tomacat乱码问题解决

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UDP消息发送

byte转化为string用构造器

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发送信息

package com.kuang.demo03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //建立Socket
        DatagramSocket socket=new DatagramSocket();

        //打包数据包
        String msg="hello";
        InetAddress address=InetAddress.getByName("localhost");
        int port=9090;

        DatagramPacket packet=new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,address,port);

        socket.send(packet);

        socket.close();
    }
}

package com.kuang.demo03;

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


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);//阻塞接收
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭连接
        socket.close();
    }
}

在线咨询

{
    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) {
            try {
                byte[] container = new byte[1024];
                DatagramPacket packet= new DatagramPacket(container, 0,container.length);
                socket.receive(packet);

                byte[] data=packet.getData();
                String receiveData=new String(data,0,data.length);

                System.out.println(msgFrom+ ":" +receiveData);

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

package com.kuang.demo03;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.*;

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 (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package com.kuang.demo03;
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();
    }

}

package com.kuang.demo03;

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下载网络资源

统一资源定位符：定位资源，定位互联网上某一个资源

DNS域名解析 WWW.baidu 解析成xxx.xx.x.x

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package com.kuang.demo04;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class URLDemo01 {
    public static void main(String[] args) throws IOException {
        URL url = new URL("https://www.baidu.com/img/baidu_85beaf5496f291521eb75ba38eacbd87.svg");
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        InputStream in = urlConnection.getInputStream();
        FileOutputStream Fout = new FileOutputStream("1.svg");

        byte[] buff = new byte[1024];
        int len;
        while ((len = in.read(buff)) != -1) {
            Fout.write(buff, 0, len);
        }

        Fout.close();
        in.close();
        urlConnection.disconnect();
    }
}

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