Java实例——网络实例

news2024/11/29 0:42:28

1、主机IP地址获取
步骤一：获取主机InetAddress
步骤二：获取主机IP地址

        InetAddress address = null;
        try {
            address = InetAddress.getByName("www.baidu.com");
        }
        catch (UnknownHostException e) {
            System.exit(2);
        }
        System.out.println("HostName" + "\t\t"
                + "IPAddress");
        System.out.println(address.getHostName() + "\t\t"
                + address.getHostAddress());
        System.exit(0);

输出结果

HostName		IPAddress
www.baidu.com		180.101.50.242

2、查看端口使用情况

   public static void main(String[] args) {
      Socket Skt;
      String host = "localhost";
      if (args.length > 0) {
         host = args[0];
      }
      for (int i = 0; i < 1024; i++) {
         try {
            System.out.println("查看 "+ i);
            Skt = new Socket(host, i);
            System.out.println("端口 " + i + " 已被使用");
         }
         catch (UnknownHostException e) {
            System.out.println("Exception occured"+ e);
            break;
         }
         catch (IOException e) {
         }
      }
   }

输出结果

……
查看 17
查看 18
查看 19
查看 20
查看 21
端口 21 已被使用
查看 22
查看 23
查看 24
……

3、获取本机ip地址及主机名

    public static void main(String[] args) throws IOException, InterruptedException {
        InetAddress inetAddress = InetAddress.getByName("www.baidu.com");
        System.out.println("主机IP地址："+inetAddress.getHostAddress());
        System.out.println("主机名称："+inetAddress.getHostName());
    }

输出结果

主机IP地址：180.101.50.242
主机名称：www.baidu.com

4、获取文件大小
步骤一：获取URL对象 new URL(“资源路径”);
步骤二：连接URL链接 URLConnection conn = url.openConnection();
步骤三：获取文件大小 conn.getContentLength();

URL url = new URL("资源路径");	//获取URL对象
URLConnection conn = url.openConnection();	//打开URL资源器
int size = conn.getContentLength();	//文件大小

5、多线程Socket

public class dictoryImpl implements Runnable {
    Socket clientSocket;

    public dictoryImpl(Socket clientSocket) {
        this.clientSocket = clientSocket;
    }

    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(1234);
        System.out.println("listening");

        while(true){
            Socket socket = serverSocket.accept();
            System.out.println("connectionLocalPort："+socket.getLocalPort());
            System.out.println("connectionCurrentPort："+socket.getPort());
            new Thread(new dictoryImpl(socket)).start();
        }
    }

    @Override
    public void run() {
        try {
            PrintStream printStream = new PrintStream(clientSocket.getOutputStream());
            for (int i = 0; i < 100; i++) {
                printStream.println(i + " bottles of beer on the wall.");
            }
            printStream.close();
            clientSocket.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

class client{
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost",1234);
        socket.close();
    }
}

输出结果

listening
connectionLocalPort：1234
connectionCurrentPort：3799

6、查看主机指定文件的最后修改时间

    public static void main(String[] args) throws IOException {
        URL url = new URL("资源路径");
        URLConnection uc = url.openConnection();
        uc.setUseCaches(false);
        long timestamp = uc.getLastModified();
        System.out.println("java.bmp 文件最后修改时间 :"+timestamp);
    }

7、使用Socket连接到指定主机

    public static void main(String[] args) throws IOException {
        InetAddress inetAddress;
        Socket socket = new Socket("www.baidu.com",80);
        inetAddress = socket.getInetAddress();
        System.out.println("连接到 "+inetAddress);
        socket.close();
    }

输出结果

连接到 www.baidu.com/180.101.50.188

8、网页抓取

    public static void main(String[] args) throws IOException {
        URL url = new URL("https://blog.csdn.net/Zain_horse/article/details/129048338");
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(url.openStream()));
        String line;
        while ((line = bufferedReader.readLine()) != null){
            System.out.println(line);
        }
        bufferedReader.close();
    }

输出结果
在这里插入图片描述
9、获取响应头日期

    public static void main(String[] args) throws IOException {
        URL url = new URL("https://blog.csdn.net/Zain_horse/article/details/129048338");
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
        long date = httpURLConnection.getDate();
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss a");
        if (date == 0){
            System.out.println("无法获取Header");
        }else {
            System.out.println("Date："+simpleDateFormat.format(date));
        }
    }

输出结果

Date：2023-02-22 22:08:26 下午

10、获取相应头信息

    public static void main(String[] args) throws IOException {
        URL url = new URL("https://blog.csdn.net/Zain_horse/article/details/129048338");
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
        Map<String, List<String>> listMap = httpURLConnection.getHeaderFields();
        Set<String> keySet = listMap.keySet();
        for (String key:keySet) {
            String val = httpURLConnection.getHeaderField(key);
            System.out.println(key+"："+val);
        }
    }

输出结果

Keep-Alive：timeout=20
Transfer-Encoding：chunked
null：HTTP/1.1 200 OK
Strict-Transport-Security：max-age= 31536000
Server：openresty
Connection：keep-alive
Set-Cookie：dc_session_id=10_1677075301490.865484; Expires=Thu, 01 Jan 2025 00:00:00 GMT; Path=/; Domain=.csdn.net;
Vary：Accept-Encoding
Content-Language：en-US
Date：Wed, 22 Feb 2023 14:15:01 GMT
Content-Type：text/html;charset=utf-8

11、解析URL

    public static void main(String[] args) throws IOException {
        URL url = new URL("https://blog.csdn.net/Zain_horse/article/details/129048338");
        System.out.println(url);
        System.out.println(url.getProtocol()+"://"+url.getHost()+url.getPort()+url.getPath());
    }

输出结果

https://blog.csdn.net/Zain_horse/article/details/129048338
https://blog.csdn.net-1/Zain_horse/article/details/129048338

12、C/S Socekt之间通信

服务器端建立过程：

服务器建立通信ServerSocket
服务器建立Socket接收客户端连接
建立IO输入流读取客户端发送的数据
建立IO输出流向客户端发送数据消息

ServerSocket 服务器端

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
   public static void main(String[] args) {
      try {
         ServerSocket ss = new ServerSocket(8888);
         System.out.println("启动服务器....");
         Socket s = ss.accept();
         System.out.println("客户端:"+s.getInetAddress().getLocalHost()+"已连接到服务器");
         
         BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));
         //读取客户端发送来的消息
         String mess = br.readLine();
         System.out.println("客户端："+mess);
         BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
         bw.write(mess+"\n");
         bw.flush();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

客户端Client建立过程：

创建Socket通信，设置通信服务器的IP和Port
建立IO输出流向服务器发送数据消息
建立IO输入流读取服务器发送来的数据消息
ClientSoceket 客户端

/*
 author by w3cschool.cn
 Main.java
 */

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException;

public class Client {
   public static void main(String[] args) {
      try {
         Socket s = new Socket("127.0.0.1",8888);
         
         //构建IO
         InputStream is = s.getInputStream();
         OutputStream os = s.getOutputStream();
         
         BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(os));
         //向服务器端发送一条消息
         bw.write("测试客户端和服务器通信，服务器接收到消息返回到客户端\n");
         bw.flush();
         
         //读取服务器返回的消息
         BufferedReader br = new BufferedReader(new InputStreamReader(is));
         String mess = br.readLine();
         System.out.println("服务器："+mess);
      } catch (UnknownHostException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

服务器端结果：
启动服务器....

客户端结果：
服务器：测试客户端和服务器通信，服务器接收到消息返回到客户端

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Java实例——网络实例

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