Question

所以我有一个服务器客户端程序，可以进行屏幕捕获并在屏幕上显示。我想在主要部分验证我要连接的端口是否正在使用，并打印一些相关的消息..

服务器：

package test;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.sql.SQLException;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Server extends Thread
{
       private ServerSocket serverSocket;
       Socket server;

       public Server(int port) throws IOException, SQLException, ClassNotFoundException, Exception
       {
          serverSocket = new ServerSocket(port);
          serverSocket.setSoTimeout(180000);
       }

       public void run()
       {
           while(true)
          { 
               try
               {
                  server = serverSocket.accept();
                  BufferedImage img=ImageIO.read(ImageIO.createImageInputStream(server.getInputStream()));
                  JFrame frame = new JFrame();
                  frame.getContentPane().add(new JLabel(new ImageIcon(img)));
                  frame.pack();
                  frame.setVisible(true);                  
              }
             catch(SocketTimeoutException st)
             {
                   System.out.println("Socket timed out!");
                  break;
             }
             catch(IOException e)
             {
                  e.printStackTrace();
                  break;
             }
             catch(Exception ex)
            {
                  System.out.println(ex);
            }
          }
       }

//       private static boolean isLocalPortInUse(int port) {
//          try {
//              // ServerSocket try to open a LOCAL port
//              new ServerSocket(port).close();
//              // local port can be opened, it's available
//              return false;
//          } catch(IOException e) {
//              // local port cannot be opened, it's in use
//              return true;
//          }
//      }

       public static void main(String [] args) throws IOException, SQLException, ClassNotFoundException, Exception
       {
              int port = 9000;
              Thread t = new Server(port);

              t.start();

       }
}

客户端：

package test;

import java.awt.AWTException;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.Socket;

import javax.imageio.ImageIO;

public class Client
{   
    static BufferedImage img;
    byte[] bytes;

    public static void main(String [] args)
    {
        String serverName = "localhost";
        int port = 10001;
        try
        {
            Socket client = new Socket(serverName, port);
            Robot bot;
            bot = new Robot();//clasa Robot ajuta la creare capturii de ecran
            img = bot.createScreenCapture(new Rectangle(0, 0, 500, 500));//scalarea imaginii; schimba dimensiunea screen shotului
            ImageIO.write(img,"JPG",client.getOutputStream());
            System.out.println("The image is on the screen!Yey!");
            client.close();
        } catch(IOException | AWTException e) {
            e.printStackTrace();
        }
    }
}

Answer 1

如果客户端和服务器位于同一个框中，则可以使用绑定到现有端口的策略并检查特定的异常。

public static void main(String...args) throws IOException {
  int port = 31999; // for demonstration purposes only.

  boolean serverRunning = isServerRunning(port);
  System.out.printf("Server running: %s\n", serverRunning);

  new ServerSocket(port); // start the server

  serverRunning = isServerRunning(port);
  System.out.printf("Server running: %s\n", serverRunning);
}

private static boolean isServerRunning(int port) throws IOException {
  try(ServerSocket clientApp = new ServerSocket(port)) {
    return false;
  } catch (java.net.BindException e) {
    return true;
  }
}

如果服务器位于另一个方框（最有可能是这种情况），那么您可以遵循类似的策略，而不是寻找ConnectException

public static void main(String...args) throws IOException {
  int port = 31999; // for demonstration purposes only.

  boolean serverRunning = isServerRunning("localhost", port);
  System.out.printf("Server running: %s\n", serverRunning);

  new ServerSocket(port); // start the server

  serverRunning = isServerRunning("localhost", port);
  System.out.printf("Server running: %s\n", serverRunning);
}

private static boolean isServerRunning(String address, int port) throws IOException {
  try(Socket clientApp = new Socket(address, port)) {
    return true;
  } catch (java.net.ConnectException e) {
    return false;
  }
}

检查您要连接的端口是否正在使用中

1 个答案: