Java-Java基础学习（2）-网络编程-TCP-UDP

2.网络编程

2.1. 通信协议

TCP、UDP对比
- TCP 打电话
  - 连接，稳定
  - 三次握手，四次挥手
```
三次握手
A: 你瞅啥？
B: 瞅你咋地？
A：干一场！四次挥手
A：我要走了
B: 你真的要走了吗？
B：你真的真的要走了吗？
A：我真的要走了
```
  - 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：洪水供给！（饱和攻击）

2.2. Tcp上传测试

1、TcpUploadClient.javapackage com.hzs.basic.inet;import java.io.*;
import java.net.Inet4Address;
import java.net.Socket;
import java.net.URL;
import java.net.UnknownHostException;/*** @author Cherist Huan* @version 1.0* @date 2021/6/8 11:39* @note 文件上传客户端*/
public class TcpUploadClient {public static void main(String[] args) throws IOException {// 1、创建一个Socket连接Socket socket = new Socket(Inet4Address.getByName("127.0.0.1"),9999);// 2、创建一个输出流OutputStream os = socket.getOutputStream();// 3、读取文件// FileInputStream fis = new FileInputStream(new File(String.valueOf(TcpUploadClient.class.getResource("6.jpg"))));//    URL resource = TcpUploadClient.class.getResource("/images/6.jpg");//    FileInputStream fis = new FileInputStream(resource.getPath());File file = new File("java-test-questions-06/src/main/resources/images/6.jpg");// File file = new File("images/6.jpg");System.out.println(file.getAbsolutePath());FileInputStream fis = new FileInputStream(file);// 4、写出文件byte[] buffer = new byte[1024];int len;while((len = fis.read(buffer))!= -1){os.write(buffer,0,len);}// 通知服务器，我已经传输完毕了socket.shutdownOutput(); // 我已经传输完毕// 接受服务器的响应，确定服务器接受完毕，才能关闭连接InputStream is2 = socket.getInputStream();byte[] buffer2 = new byte[1024];int len2;ByteArrayOutputStream baos = new ByteArrayOutputStream();while((len2 = is2.read(buffer2))!= -1){baos.write(buffer2,0,len2);}System.out.println(baos.toString());// 5、关闭资源baos.close();fis.close();os.close();socket.close();}
}

2、TcpUploadServer.javapackage com.hzs.basic.inet;import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URL;/*** @author Cherist Huan* @version 1.0* @date 2021/6/8 11:39*  @note 文件上传服务端*/
public class TcpUploadServer {public static void main(String[] args) throws IOException {// 1、创建ServerSocketServerSocket serverSocket = new ServerSocket(9999);// 2、创建Socket监听Socket socket = serverSocket.accept();// 3、获取输入流InputStream is = socket.getInputStream();// 4、文件输出//        URL resource = TcpUploadClient.class.getResource("/images/6_receive.jpg");
//        //FileOutputStream fos = new FileOutputStream(new File(resource.getPath()));
//        FileOutputStream fos = new FileOutputStream(resource.getPath());File file = new File("java-test-questions-06/src/main/resources/images/6receive.jpg");//File file = new File("images/6_receive.jpg");FileOutputStream fos = new FileOutputStream(file);byte[] buffer;buffer = new byte[1024];int len;while((len = is.read(buffer))!= -1){fos.write(buffer,0,len);}// 通知客户端，我已经接受完毕OutputStream os = socket.getOutputStream();os.write("服务端返回，服务端已经接受完毕了".getBytes());// 5、关闭资源os.close();fos.close();is.close();socket.close();serverSocket.close();}
}

总结：

客户端
1. 建立socket连接
2. 创建一个输出管道流
3. 读取需要上传的文件
4. 将文件写出到管道流
5. 通知服务器，我已经传输完毕
6. 接受服务器的响应，确定服务器接受完毕，才能关闭连接
7. 关闭资源
服务端
1. 建立ServerSocker端口服务
2. 创建Socket监听，返回Socket
3. 获取输入流
4. 获取输入流中文件输出
5. 通知客户端，我已经接受完毕
6. 关闭资源

2.3. Udp 传输

1、UdpClient.javapackage com.hzs.basic.inet;import java.io.IOException;
import java.net.*;/*** @Author Cherist Huan* @Date 2021/6/10 10:41* @Version 1.0*/
public class UdpClient {public static void main(String[] args) throws IOException {// System.out.println(("AB".getBytes()).length);//2// 1、建立一个SocketDatagramSocket socket = new DatagramSocket();// 2、建包String msg = "Hello Cherist Huan!";InetAddress byName = Inet4Address.getByName("127.0.0.1");int port = 9090;DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,byName,port);// 3、发送包socket.send(datagramPacket);// 4、关闭流socket.close();}
}

2、UdpServer.javapackage com.hzs.basic.inet;import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;/*** @Author Cherist Huan* @Date 2021/6/10 10:57* @Version 1.0*/
public class UdpServer {public static void main(String[] args) throws IOException {// 1、开放端口DatagramSocket datagramSocket = new DatagramSocket(9090);// 2、接受数据包byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);datagramSocket.receive(packet);// 阻塞式接受System.out.println(new String(packet.getData(),0,packet.getLength()));// 关闭流datagramSocket.close();}
}

2.4. Udp聊天室（多线程）

1、TalkSend.java
package com.hzs.basic.inet;import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.*;/*** @Author Cherist Huan* @Date 2021/6/10 15:24* @Version 1.0*/
public class TalkSend implements  Runnable {DatagramSocket socket = null;BufferedReader reader = null;private  int fromPort;private  int toPort;private  String toIp;public TalkSend(int fromPort, int toPort, String toIp) {this.fromPort = fromPort;this.toPort = toPort;this.toIp = toIp;try {socket = new DatagramSocket(fromPort);reader = new BufferedReader(new InputStreamReader(System.in));} catch (SocketException e) {e.printStackTrace();}}public void run() {while(true){try {String data = reader.readLine();byte[] dataBytes = data.getBytes();DatagramPacket packet = new DatagramPacket(dataBytes,0,dataBytes.length,new InetSocketAddress(this.toIp,this.toPort));socket.send(packet);if(data.equals("bye")){break;}} catch (IOException e) {e.printStackTrace();}}socket.close();}
}2、TalkReceive.java
package com.hzs.basic.inet;import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;/*** @Author Cherist Huan* @Date 2021/6/10 15:44* @Version 1.0*/
public class TalkReceive  implements  Runnable{DatagramSocket socket = null;private int port;private  String msg;public  TalkReceive(int port,String msg){this.port = port;this.msg = msg;try {socket = new DatagramSocket(port);} catch (SocketException e) {e.printStackTrace();}}public void run() {while(true){try {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 byebyte[] data = packet.getData();String receiveData = new String(data,0,data.length);System.out.println(msg+":"+receiveData);if(receiveData.equals("bye")){break;}} catch (IOException e) {e.printStackTrace();}}socket.close();}
}3、TalkStudent.java
package com.hzs.basic.inet;/*** @Author Cherist Huan* @Date 2021/6/10 15:56* @Version 1.0*/
public class TalkStudent {public static void main(String[] args) {// 开启两个线程new Thread(new TalkSend(7777,9999,"localhost")).start();//学生端接受线程端口（服务端口 8888）new Thread(new TalkReceive(8888,"老师说")).start();}
}4、TalkTeacher.java
package com.hzs.basic.inet;/*** @Author Cherist Huan* @Date 2021/6/10 16:04* @Version 1.0*/
public class TalkTeacher {public static void main(String[] args) {// 开启两个线程new Thread(new TalkSend(6666,8888,"localhost")).start();//老师端接受线程端口（服务端口 9999）new Thread(new TalkReceive(9999,"学生说")).start();}
}