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(); } }