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

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  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

  • 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

  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();}}}
  

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SocketDatagramSocket 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();}}@Overridepublic 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();}}@Overridepublic 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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eg:https://mp.csdn.net/console/home?spm=1001.2101.3001.4503

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();}
}