【狂神Java笔记】Java网络编程实战详细笔记整理（附代码）

1.1 概述

计算机网络：

计算机网络是指将地理位置不同的具有独立功能的多台计算机及其外部设备，通过通信线路连接起来，在网络操作系统，网络管理软件及网络通信协议的管理和协调下，实现资源共享和信息传递的计算机系统。

网络编程的目的：

无线电台…传播交流信息

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,如何传输数据呢?

javaweb：网页编程 B/S
网络编程：TCP/P C/S

1.2 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

OSI模型

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者多台主机
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

3、万物皆对象

1.3 IP

ip 地址: netAddress

1、唯一定位一台网络上计算机
2、127.0.0.1：本机 localhost
3、ip 地址的分类

ipv4/ ipV6

IPV41270.0.1, 4个字节组成。 0-255 42亿~ 30亿都在北美，亚洲4亿。 2011年就用尽公网私网
IPV6：128位。8个无符号整数!

公网(互联网)-私网(局域网)

ABCD类地址
192.168.X.XX，专门给组织内部使用的

域名：记忆IP问题!

package com.blue.lesson01;import java.net.InetAddress;
import java.net.UnknownHostException;public class TextInetAddress {public static void main(String[] args) {try {//查询本机地址InetAddress interaddress1 = InetAddress.getByName("127.0.0.1");System.out.println(interaddress1);InetAddress interaddress3 = InetAddress.getByName("localhost");System.out.println(interaddress1);InetAddress interaddress4 = InetAddress.getLocalHost();System.out.println(interaddress1);//查询网站IP地址InetAddress interaddress2 = InetAddress.getByName("www.baidu.com");System.out.println(interaddress2);//常用方法System.out.println(interaddress2.getAddress());System.out.println(interaddress2.getCanonicalHostName());  //规范的名字System.out.println(interaddress2.getHostAddress()); //ipSystem.out.println(interaddress2.getHostName());  //域名,或者自已电脑的名字} 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：

1、不同的进程有不同的端口号，用来区分软件!

2、被规定0-65535

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

4、端口分类

公有端口 0~1023
Http： 80
Https： 443
FTP： 21
Telent： 23

5、程序注册端口：1024-49151，分配用户或者程序

Tomcat: 8080
MySQL: 3306
Oracle： 1521

6、动态、私有: 49152~65535

netstat-ano #查看所有的端口
netstat-ano|findstr"5900"  #查看指定的端口
task1ist|findstr"8696"  #查看指定端口的进程

package com.blue.lesson01;import java.net.InetSocketAddress;public class TextInetSocketAddress {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.getPort());  //端口}
}

1.5 通信协议

协议：约定,就好比我们现在说的是普通话。

网络通信协议：速率,传输码率,代码结构,传输控制

问题：非常的复杂?

TCPIP 协议簇

重要

TCP：用户传输协议
UDP：用户数据报协议

IP：网络互连协议

TCP UDP 对比

TCP:打电话

连接,稳定
三次握手四次挥手
客户端、服务端
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
导弹
DDOS：洪水攻击!r(饱和攻击)

三次握手和四次挥手

三次握手和四次挥手（面试必问） - My_Dreams - 博客园 (cnblogs.com)

1.6 TCP

客户端

连接服务器 Socket
发送消息

服务器

建立服务的端口 Serversocket
等待用户的链接 accept
接收用的湖息

客户端：

package com.blue.lesson02;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) {InetAddress serverIP = null;Socket socket = null;OutputStream os = null;try {//1.要知道服务器的地址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 (UnknownHostException e) {e.printStackTrace();} catch (IOException 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：

package com.blue.lesson02;import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;//服务器
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);//2.等待客户端连接过来while (true){socket = serverSocket.accept();//3.读收客户端的消息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 {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.blue.lesson02;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 {//1.创一个 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. 文件流FileInputStream fis = new FileInputStream(new File("cat-6723256.jpg"));//4.文件输出byte[] buffer = new byte[1024];int len;while ((len=fis.read(buffer))!=-1){os.write(buffer,0,len);}//通知服务器，我已经结束了socket.shutdownOutput();//确定服务器接收完体,才能够断开连按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();os.close();socket.close();}}

服务端：

package com.blue.lesson02;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.监听客户端连接Socket socket = serverSocket.accept();//3.获取输出流InputStream is = socket.getInputStream();//4.文件输出FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));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华了OutputStream os = socket.getOutputStream();os.write("我接收完毕了，你可以断开了".getBytes());//关闭资源fos.close();is.close();socket.close();serverSocket.close();}
}

Tomacat

服务端

自定义S
Tomcat 服务器S Java后台开发!

客户端

自定义C
浏览器B

Tomcat 下载与安装：Tomcat下载和安装（图解） (biancheng.net)

1.7 UDP

发送消息

客户端：

package com.blue.lesson03;import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;//不而要连接服务器
public class UdpClientDemo01 {public static void main(String[] args) throws Exception {//1.建立一个 SocketDatagramSocket socket = new DatagramSocket();//2.建个包String msg = "你好啊,服务器!";int port = 9090;//发送给谁InetAddress localhost = InetAddress.getByName("localhost");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();}
}

服务端：

package com.blue.lesson03;import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;public class UdpServerDemo01 {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);//阻塞接收System.out.println(packet.getAddress().getHostAddress());System.out.println(new String(packet.getData(),0,packet.getLength()) );System.out.println(packet);//关闭连接socket.close();}
}

循环发送消息

发送端：

package com.blue.chat;import java.io.BufferedReader;
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:控制台读收 System.inBufferedReader 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();}
}

接收端：

package com.blue.chat;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){//准备接受包裹byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0, container.length);socket.receive(packet);//阻塞式接受包裹//断开连接byte[] data = packet.getData();String receiveData = new String(data, 0, packet.getLength());System.out.println(receiveData);if (receiveData.equals("bye")){break;}}socket.close();}
}

在线咨询

发送端

package com.blue.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{DatagramSocket socket = null;BufferedReader reader = null;private int fromPort; //对方端口号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 (Exception e){e.printStackTrace();}socket.close();}}
}

接收端

package com.blue.chat;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();}}@Overridepublic void run() {while (true){try {//准备接受包裹byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0, container.length);socket.receive(packet);//阻塞式接受包裹//断开连接byte[] data = packet.getData();String receiveData = new String(data, 0, packet.getLength() );System.out.println(msgFrom+": "+receiveData);if (receiveData.equals("bye")){break;}} catch (IOException e) {e.printStackTrace();}}socket.close();}
}

学生线程

package com.blue.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();}}

老师线程

package com.blue.chat;public class TalkTeacher {public static void main(String[] args) {//开启两个线程new Thread(new TalkSend(5555,"localhost",8888)).start();new Thread(new TalkReceive(9999,"学生")).start();}
}

1.8 URL

https://www.baidu.com

统一资源定位符：定位资源的，定位互联网上的某一个资源

DNS域名解析——www.baidu.comb xxx.x.x…x

协议://ip地址:端口/项目名/资源

package com.blue.lesson04;import java.net.MalformedURLException;
import java.net.URL;public class URLDemo01 {public static void main(String[] args) throws MalformedURLException {URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=kuangshen&password=123");System.out.println(url.getProtocol());  //协议System.out.println(url.getHost());   //主机System.out.println(url.getPort());    //端口System.out.println(url.getPath());   //路径System.out.println(url.getFile());   //文件 全路径System.out.println(url.getQuery());   //URL查询名字 参数}
}

下载资源：

package com.blue.lesson04;import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;public class URLDown {public static void main(String[] args) throws Exception {//1.下我地址URL url = new URL("https://m701.music.126.net/20220123220857/b014483528776645552494faff4733a0/jdyyaac/obj/w5rDlsOJwrLDjj7CmsOj/11506531065/c33e/3db1/f24c/d25af884b0dc20c1179631516e93341a.m4a");//2.连接到这个资源 HTTPHttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();InputStream inputStream = urlConnection.getInputStream();FileOutputStream fos = new FileOutputStream("y.m4a");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}
}