实验九 Java 语言网络通信程序设计练习(课内实验)

一、实验目的

本次实验的主要目的是练习网络通信程序的设计方法，并掌握计算机网络基
础知识、Java语言网络通信程序类库的结构和使用方法。

二、实验要求

1. 认真阅读实验内容，完成实验内容所设的题目。
2. 能够应用多种编辑环境编写Java语言源程序。
3. 认真体会计算机网络和Java语言网络通信程序的概念。
4. 将实验结果书写在实验报告中。

三、实验内容

运行下列程序，观察程序的运行结果

A.程序一

package org.example;import java.io.*;
import java.util.Scanner;
import java.net.InetAddress;
import java.net.UnknownHostException;public class Main {public static void main(String[] args) throws Exception {InetAddress inet = InetAddress.getByName("www.baidu.com");System.out.println(inet);System.out.println(inet.getHostName());System.out.println(inet.getHostAddress());InetAddress inet1 = InetAddress.getLocalHost();System.out.println(inet1);System.out.println(inet1.getHostName());System.out.println(inet1.getHostAddress());}
}

运行结果如下

B.程序二

服务器端(Main)

package org.example;// 服务器端
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;public class Main {public static void main(String[] args) {ServerSocket ss = null;Socket s = null;InputStream is = null;OutputStream os = null;try {ss = new ServerSocket(9090);s = ss.accept();is = s.getInputStream();byte[] b = new byte[20];int len;while ((len = is.read(b)) != -1) {String str = new String(b, 0, len);System.out.print(str);}System.out.println("收到来自于" + s.getInetAddress().getHostAddress() + "的连接");os = s.getOutputStream();os.write("我已收到你的信息".getBytes());} catch (IOException e) {e.printStackTrace();} finally {if (is != null) {try {is.close();} catch (IOException e) {e.printStackTrace();}}if (s != null) {try {s.close();} catch (IOException e) {e.printStackTrace();}}if (ss != null) {try {ss.close();} catch (IOException e) {e.printStackTrace();}}}}
}

运行完服务器端后再运行客户端返回看即可出现127.0.0.1

客户端(Client)

package org.example;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;public class Client {public static void main(String[] args) {Socket socket = null;OutputStream os = null;InputStream is = null;try {socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);os = socket.getOutputStream();os.write("我是客户端，请多关照".getBytes());socket.shutdownOutput();is = socket.getInputStream();byte[] b = new byte[20];int len;while ((len = is.read(b)) != -1) {String str = new String(b, 0, len);System.out.print(str);}} 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();}}}}
}

先运行Main然后再运行Client

运行结果如下

C．程序三

接收端(UDPserver)

package org.example;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;public class UDOserver {public static void main(String[] args) {DatagramSocket ds = null;try {ds = new DatagramSocket(9090);byte[] b = new byte[1024];DatagramPacket pack = new DatagramPacket(b, 0, b.length);ds.receive(pack);String str = new String(pack.getData(), 0, pack.getLength());System.out.println(str);} catch (IOException e) {e.printStackTrace();} finally {if (ds != null) {ds.close();}}}
}

发送端(UDPclient)

package org.example;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;public class UDPclient {public static void main(String[] args) {DatagramSocket ds = null;try {ds = new DatagramSocket();byte[] b = "你好，我是要发送的数据".getBytes();DatagramPacket pack = new DatagramPacket(b, 0, b.length, InetAddress.getByName("127.0.0.1"), 9090);ds.send(pack);} catch (IOException e) {e.printStackTrace();} finally {if (ds != null) {ds.close();}}}
}

D．程序四

package org.example;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
public class Fyt {public static void main(String[] args) throws Exception {URL url = new URL("http://www.hhdu.edu.cn/85/c9/c23a34249/page.htm");System.out.println(url.getProtocol());System.out.println(url.getHost());System.out.println(url.getPort());System.out.println(url.getFile());System.out.println(url.getRef());System.out.println(url.getQuery());InputStream is = url.openStream();byte[] b = new byte[20];int len;len = is.read(b);String str = new String(b, 0, len);System.out.print(str);is.close();URLConnection urlConn = url.openConnection();InputStream is1 = urlConn.getInputStream();FileOutputStream fos = new FileOutputStream(new File("E:\\桌面文件\\javatxt文档\\a.txt"));byte[] b1 = new byte[20];int len1;while ((len1 = is1.read(b1)) != -1) {fos.write(b1, 0, len1);}fos.close();is1.close();}
}

1.这个代码类似于抓包了,大概意思是从指定的URL上下载文件并将其内容保存到本地文件中。使用URL类创建一个指向特定URL的对象，然后通过对该URL对象调用方法来获取URL的各种属性，如协议、主机名、端口、文件名、引用和查询部分。
2.接着，打开URL的输入流，从URL地址对应的资源中读取内容。在这里，首先创建一个字节数组b用于存放读取到的数据，使用输入流is的read(b)方法读取数据，然后将字节数组转换成字符串并打印输出。
3.随后，通过url.openConnection()方法创建一个URLConnection对象，并从中获取输入流is1。然后创建一个FileOutputStream对象fos，将从输入流is1读取的数据写入到本地文件"E:\\桌面文件\\javatxt文档\\a.txt"中。
4.最后，关闭所有打开的流，释放相关的资源。
这段代码的作用是连接到指定URL，抓取该URL对应的资源，然后将其内容保存为本地文件。

本地文件如下图所示

四、编写程序完成下列功能

（1）编写一个服务器端的程序Server.java，该程序在8000端口监听客户端的

请求，如果与客户端连接后，收到客户端发送的数据不是字符串“bye”，则在服

务器端打印客户端发来的数据，并向客户端回送一条从键盘输入的信息，若客户

端发来的数据是字符串“bye”，则关闭服务器端程序。

package org.example;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;public class Server {public static void main(String[] args) {try {ServerSocket serverSocket = new ServerSocket(8000);System.out.println("服务器已启动，等待客户端连接...");while (true) {Socket clientSocket = serverSocket.accept();System.out.println("客户端已连接");BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));Scanner scanner = new Scanner(System.in);String clientMessage;while ((clientMessage = reader.readLine()) != null) {System.out.println("客户端消息：" + clientMessage);if (clientMessage.equals("bye")) {System.out.println("客户端已断开连接");break;} else {System.out.print("请输入要发送给客户端的信息：");String serverResponse = scanner.nextLine();writer.write(serverResponse);writer.newLine();writer.flush();}}reader.close();writer.close();clientSocket.close();if (clientMessage.equals("bye")) {System.out.println("关闭服务器端程序");break;}}serverSocket.close();} catch (IOException e) {e.printStackTrace();}}
}

（2）编写一个服务器端ServerDemo.java程序，它能够响应客户的请求。如

果这个请求的内容是字符串"hello"的话，服务器仅将"welcome!"字符串返回给用

户。否则将用户的话追加到当前目录的文本文件log.txt中，并向用户返回"OK!"。

package org.example;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;public class ServerDemo {public static void main(String[] args) {try {ServerSocket serverSocket = new ServerSocket(8001);System.out.println("服务器已启动，等待客户端连接...");while (true) {Socket clientSocket = serverSocket.accept();System.out.println("客户端已连接");BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));String clientMessage = reader.readLine();if ("hello".equals(clientMessage)) {writer.write("welcome!");} else {File file = new File("E:\\桌面文件\\javatxt文档\\a.txt");FileWriter fileWriter = new FileWriter(file, true);BufferedWriter logWriter = new BufferedWriter(fileWriter);logWriter.write(clientMessage);logWriter.newLine();logWriter.close();writer.write("OK!");}writer.newLine();writer.flush();reader.close();writer.close();clientSocket.close();}} catch (IOException e) {e.printStackTrace();}}
}