UDP 类似于发短信，不用连接，只需要知道接收端的地址发送消息发送端package com.network.lesson03; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; /** * @Author suaxi * @Date 2020/11/23 11:03 * UDP发送消息，不需要连接服务器 */ public class UpdClientDemo01 { public static void main(String[] args) throws Exception { //1、建立一个socket DatagramSocket datagramSocket = new DatagramSocket(); //2、建立包 String mgs = "故乡的樱花开了！"; InetAddress localhost = InetAddress.getByName("localhost"); int port = 8888; //数据 数据的长度起始 要发送给谁 DatagramPacket datagramPacket = new DatagramPacket(mgs.getBytes(), 0, mgs.length(),localhost,port); //3、发送包 datagramSocket.send(datagramPacket); //4、关闭流 datagramSocket.close(); } } 接收端package com.network.lesson03; import java.net.DatagramPacket; import java.net.DatagramSocket; /** * @Author suaxi * @Date 2020/11/23 11:18 * UDP接收端，还是要等待客户端的连接 */ public class UpdServerDemo01 { public static void main(String[] args) throws Exception { //开放端口 DatagramSocket datagramSocket = new DatagramSocket(8888); //接收数据包 byte[] bytes = new byte[1024]; DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length); datagramSocket.receive(datagramPacket); //阻塞接收 System.out.println(datagramPacket.getAddress().getHostAddress()); //接收地址 System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength())); //数据包消息 //关闭连接 datagramSocket.close(); } } 循环发送消息package com.network.chat; import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.InetSocketAddress; /** * @Author suaxi * @Date 2020/11/23 11:34 * 发送消息 */ public class UdpSenderDemo01 { public static void main(String[] args) throws Exception { DatagramSocket datagramSocket = new DatagramSocket(8888); //准备数据，控制台读取输入的数据System.in BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in)); while (true){ String data = bufferedReader.readLine(); byte[] bytes = data.getBytes(); DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress("localhost", 8889)); datagramSocket.send(packet); if (data.equals("bye")){ break; } } datagramSocket.close(); } } package com.network.chat; import java.net.DatagramPacket; import java.net.DatagramSocket; /** * @Author suaxi * @Date 2020/11/23 11:34 * UDP聊天咨询Demo（循环接收） */ public class UdpReciverDemo01 { public static void main(String[] args) throws Exception { DatagramSocket datagramSocket = new DatagramSocket(8889); while (true){ //准备接收包裹 byte[] bytes = new byte[1024]; DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length); datagramSocket.receive(datagramPacket); //阻塞式接收包裹 byte[] data = datagramPacket.getData(); String reciveData = new String(data, 0, data.length); System.out.println(reciveData); //断开连接 if (reciveData.equals("bye")){ break; } } datagramSocket.close(); } } 在线咨询，两者都是发送方，也都可以是接收方发送端package com.network.chat; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetSocketAddress; import java.net.SocketException; /** * @Author suaxi * @Date 2020/11/23 14:37 */ public class TalkSend implements Runnable{ DatagramSocket datagramSocket = null; BufferedReader bufferedReader = 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 { datagramSocket = new DatagramSocket(fromPort); bufferedReader = new BufferedReader(new InputStreamReader(System.in)); } catch (SocketException e) { e.printStackTrace(); } } @Override public void run() { while (true){ try { String data = bufferedReader.readLine(); byte[] bytes = data.getBytes(); DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress(this.toIP, this.toPort)); datagramSocket.send(packet); if (data.equals("bye")){ break; } } catch (IOException e) { e.printStackTrace(); } } datagramSocket.close(); } } 接收端package com.network.chat; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.SocketException; /** * @Author suaxi * @Date 2020/11/23 14:43 */ public class TalkRecive implements Runnable{ DatagramSocket datagramSocket = null; private int port; private String mgsFrom; public TalkRecive(int port,String mgsFrom) { this.port = port; this.mgsFrom = mgsFrom; try { datagramSocket = new DatagramSocket(port); } catch (SocketException e) { e.printStackTrace(); } } @Override public void run() { while (true){ try { //准备接收包裹 byte[] bytes = new byte[1024]; DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length); datagramSocket.receive(datagramPacket); //阻塞式接收包裹 byte[] data = datagramPacket.getData(); String reciveData = new String(data, 0, data.length); System.out.println(mgsFrom+":"+reciveData); //断开连接 if (reciveData.equals("bye")){ break; } } catch (IOException e) { e.printStackTrace(); } } datagramSocket.close(); } } 具体实现：package com.network.chat; /** * @Author suaxi * @Date 2020/11/23 14:46 */ public class TalkStudent { public static void main(String[] args) { //开启两个线程 new Thread(new TalkSend(7777,"localhost",8888)).start(); new Thread(new TalkRecive(9999,"老师")).start(); } } package com.network.chat; /** * @Author suaxi * @Date 2020/11/23 14:48 */ public class TalkTeacher { public static void main(String[] args) { new Thread(new TalkSend(7778,"localhost",9999)).start(); new Thread(new TalkRecive(8888,"学生")).start(); } }

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）TCP：用户传输协议UDP：用户数据报协议TCP与UDP对比：TCP：连接、稳定三次握手，四次挥手最少需要三次，保证稳定链接 A：咋地! B：干啥？ A：干一架 A：我要走了 B：你要走了吗 B：你真的要走了吗 A：走了客户端、服务端传输完成，释放连接。效率低UDP：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（饱和攻击）TCP客户端：1、连接服务器socket2、发送消息package com.network.lesson02; import java.io.IOException; import java.io.OutputStream; import java.net.InetAddress; import java.net.Socket; import java.net.UnknownHostException; /** * @Author suaxi * @Date 2020/11/20 17:37 * 客户端 */ public class TcpClientDemo01 { public static void main(String[] args) { Socket socket = null; OutputStream os = null; //1、要知道服务器的地址、端口号 try { InetAddress serverIp = InetAddress.getByName("127.0.0.1"); int port = 8888; //2、创建一个socke连接 socket = new Socket(serverIp, port); //3、发送消息、IO流 os = socket.getOutputStream(); os.write("故乡的樱花开了".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(); } } } } } 服务器1、建立服务端口ServerSocket2、等待用户连接3、接收客户端发送的消息（管道流）package com.network.lesson02; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.ServerSocket; import java.net.Socket; /** * @Author suaxi * @Date 2020/11/20 17:38 * 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、建立服务器地址 serverSocket = new ServerSocket(8888); while (true){ //2、等待客户端连接 socket = serverSocket.accept(); //3、读取客户端消息 is = socket.getInputStream(); //管道流 baos = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int length; while ((length=is.read(buffer))!=-1){ baos.write(buffer,0,length); } System.out.println(baos); } } 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(); } } } } } 文件上传服务端package com.network.lesson02; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.ServerSocket; import java.net.Socket; /** * @Author suaxi * @Date 2020/11/22 11:26 * 文件上传服务端 */ public class TcpServerDemo02 { public static void main(String[] args) throws IOException { //1、创建服务 ServerSocket serverSocket = new ServerSocket(8889); //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 fileOutputStream = new FileOutputStream("recive.jpg"); byte[] bytes = new byte[1024]; int length; while ((length=is.read(bytes))!=-1){ fileOutputStream.write(bytes,0,length); } //通知客户端文件接收完毕 OutputStream os = socket.getOutputStream(); os.write("文件上传成功！".getBytes()); //5、关闭资源 fileOutputStream.close(); is.close(); socket.close(); serverSocket.close(); } } 客户端package com.network.lesson02; import java.io.*; import java.net.InetAddress; import java.net.Socket; /** * @Author suaxi * @Date 2020/11/22 11:26 * 文件上传客户端 */ public class TcpClientDemo02 { 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"),8889); //2、创建一个输出流 OutputStream os = socket.getOutputStream(); //3、读取文件 FileInputStream fileInputStream = new FileInputStream(new File("test.jpg")); //4、写出文件 byte[] bytes1 = new byte[1024]; int length1; while((length1=fileInputStream.read(bytes1))!=-1){ os.write(bytes1,0,length1); } //通知服务器已经上传完毕 socket.shutdownOutput(); //确定服务器接收完毕，才断开连接 InputStream inputStream = socket.getInputStream(); ByteArrayOutputStream baos = new ByteArrayOutputStream(); byte[] bytes2 = new byte[1024]; int length2; while ((length2=inputStream.read(bytes2))!=-1){ baos.write(bytes2,0,length2); } System.out.println(baos.toString()); //5、关闭资源 baos.close(); inputStream.close(); fileInputStream.close(); os.close(); socket.close(); } }

端口 端口表示计算机上的一个程序进程不同的进程有不同的端口号，用来区分软件规定范围0~65535（TCP/UDP的规范是一样的）单个协议下端口号不能冲突端口分类：公有端口0~1023HTTP：80HTTPS：443FTP：21SSH：22Telent：23程序注册端口：1024~49151，分配给用户或者程序Tomacat：8080MySQL：3306Oracle：1521RDP：3389动态、私有：49152~65535netstat -ano #查看所有的端口 netstat -ano|findstr "5900" #查看指定的端口 tasklist|findstr "8696" #查看指定端口的进程package com.network.lesson01; import java.net.InetSocketAddress; /** * @Author suaxi * @Date 2020/11/20 17:21 */ public class TestInetSocketAddress { public static void main(String[] args) { InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080); System.out.println(inetSocketAddress); System.out.println(inetSocketAddress.getAddress()); System.out.println(inetSocketAddress.getHostName()); //地址 System.out.println(inetSocketAddress.getPort()); //端口 } }

IP ip地址：InetAddress唯一定位一台网络上的计算机127.0.0.1：本机localhostip地址的分类ipv4/ipv6IPV4：4个字节组成，0~255，约42亿个IPV6：128位，8个无符号整数，例如240e:1234:abcd:0010:2b58:9900:add2:b156公网（互联网）--私网（局域网）ABCD段package com.network.lesson01; import java.net.InetAddress; import java.net.UnknownHostException; /** * @Author suaxi * @Date 2020/11/20 16:54 */ public class TestInetAddress { public static void main(String[] args) { try { //查询本机地址 InetAddress host1 = InetAddress.getByName("localhost"); System.out.println(host1); //查询网站ip地址 InetAddress host2 = InetAddress.getByName("www.baidu.com"); System.out.println(host2); //常用方法 System.out.println(host2.getAddress()); System.out.println(host2.getCanonicalHostName()); //规范的名字 System.out.println(host2.getHostAddress()); //ip System.out.println(host2.getHostName()); //域名或自己电脑的名字 } catch (UnknownHostException e) { e.printStackTrace(); } } }