¿Hay alguna manera de tomar una captura de pantalla usando Java y guardarla en algún tipo de imagen?

Simple como dice el título: ¿Puedes usar solo comandos Java para tomar una captura de pantalla y guardarla? ¿O necesito usar un programa específico del sistema operativo para tomar la captura de pantalla y luego tomarla del portapapeles?

Lo creas o no, en realidad puedes usarlo java.awt.Robotpara "crear una imagen que contenga píxeles leídos desde la pantalla". Luego puede escribir esa imagen en un archivo en el disco.

Acabo de intentarlo, y todo termina así:

Rectangle screenRect = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
BufferedImage capture = new Robot().createScreenCapture(screenRect);
ImageIO.write(capture, "bmp", new File(args[0]));

NOTA: Esto solo capturará el monitor primario. Vea GraphicsConfiguration para soporte de monitores múltiples.

Nunca me gustó usar Robot, así que hice mi propio método simple para hacer capturas de pantalla de objetos JFrame:

public static final void makeScreenshot(JFrame argFrame) {
    Rectangle rec = argFrame.getBounds();
    BufferedImage bufferedImage = new BufferedImage(rec.width, rec.height, BufferedImage.TYPE_INT_ARGB);
    argFrame.paint(bufferedImage.getGraphics());

    try {
        // Create temp file
        File temp = File.createTempFile("screenshot", ".png");

        // Use the ImageIO API to write the bufferedImage to a temporary file
        ImageIO.write(bufferedImage, "png", temp);

        // Delete temp file when program exits
        temp.deleteOnExit();
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
}

Si desea capturar todos los monitores, puede usar el siguiente código:

GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice[] screens = ge.getScreenDevices();

Rectangle allScreenBounds = new Rectangle();
for (GraphicsDevice screen : screens) {
    Rectangle screenBounds = screen.getDefaultConfiguration().getBounds();

    allScreenBounds.width += screenBounds.width;
    allScreenBounds.height = Math.max(allScreenBounds.height, screenBounds.height);
}

Robot robot = new Robot();
BufferedImage screenShot = robot.createScreenCapture(allScreenBounds);

public void captureScreen(String fileName) throws Exception {
   Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
   Rectangle screenRectangle = new Rectangle(screenSize);
   Robot robot = new Robot();
   BufferedImage image = robot.createScreenCapture(screenRectangle);
   ImageIO.write(image, "png", new File(fileName));
}

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File; 
import javax.imageio.ImageIO;
import javax.swing.*;  

public class HelloWorldFrame extends JFrame implements ActionListener {

JButton b;
public HelloWorldFrame() {
    this.setVisible(true);
    this.setLayout(null);
    b = new JButton("Click Here");
    b.setBounds(380, 290, 120, 60);
    b.setBackground(Color.red);
    b.setVisible(true);
    b.addActionListener(this);
    add(b);
    setSize(1000, 700);
}
public void actionPerformed(ActionEvent e)
{
    if (e.getSource() == b) 
    {
        this.dispose();
        try {
            Thread.sleep(1000);
            Toolkit tk = Toolkit.getDefaultToolkit(); 
            Dimension d = tk.getScreenSize();
            Rectangle rec = new Rectangle(0, 0, d.width, d.height);  
            Robot ro = new Robot();
            BufferedImage img = ro.createScreenCapture(rec);
            File f = new File("myimage.jpg");//set appropriate path
            ImageIO.write(img, "jpg", f);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
}

public static void main(String[] args) {
    HelloWorldFrame obj = new HelloWorldFrame();
}
}

GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();  
GraphicsDevice[] screens = ge.getScreenDevices();       
Rectangle allScreenBounds = new Rectangle();  
for (GraphicsDevice screen : screens) {  
       Rectangle screenBounds = screen.getDefaultConfiguration().getBounds();        
       allScreenBounds.width += screenBounds.width;  
       allScreenBounds.height = Math.max(allScreenBounds.height, screenBounds.height);
       allScreenBounds.x=Math.min(allScreenBounds.x, screenBounds.x);
       allScreenBounds.y=Math.min(allScreenBounds.y, screenBounds.y);
      } 
Robot robot = new Robot();
BufferedImage bufferedImage = robot.createScreenCapture(allScreenBounds);
File file = new File("C:\\Users\\Joe\\Desktop\\scr.png");
if(!file.exists())
    file.createNewFile();
FileOutputStream fos = new FileOutputStream(file);
ImageIO.write( bufferedImage, "png", fos );

bufferedImage contendrá una captura de pantalla completa, esto se probó con tres monitores

Puedes usar java.awt.Robotpara lograr esta tarea.

a continuación se muestra el código del servidor, que guarda la captura de pantalla capturada como imagen en su Directorio.

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.sql.SQLException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.imageio.ImageIO;

public class ServerApp extends Thread
{
       private ServerSocket serverSocket=null;
       private static Socket server = null;
       private Date date = null;
       private static final String DIR_NAME = "screenshots";

   public ServerApp() throws IOException, ClassNotFoundException, Exception{
       serverSocket = new ServerSocket(61000);
       serverSocket.setSoTimeout(180000);
   }

public void run()
   {
       while(true)
      {
           try
           {
              server = serverSocket.accept();
              date = new Date();
                  DateFormat dateFormat = new SimpleDateFormat("_yyMMdd_HHmmss");
              String fileName = server.getInetAddress().getHostName().replace(".", "-");
              System.out.println(fileName);
              BufferedImage img=ImageIO.read(ImageIO.createImageInputStream(server.getInputStream()));
              ImageIO.write(img, "png", new File("D:\\screenshots\\"+fileName+dateFormat.format(date)+".png"));
              System.out.println("Image received!!!!");
              //lblimg.setIcon(img);
          }
         catch(SocketTimeoutException st)
         {
               System.out.println("Socket timed out!"+st.toString());
 //createLogFile("[stocktimeoutexception]"+stExp.getMessage());
                  break;
             }
             catch(IOException e)
             {
                  e.printStackTrace();
                  break;
         }
         catch(Exception ex)
        {
              System.out.println(ex);
        }
      }
   }

   public static void main(String [] args) throws IOException, SQLException, ClassNotFoundException, Exception{
          ServerApp serverApp = new ServerApp();
          serverApp.createDirectory(DIR_NAME);
          Thread thread = new Thread(serverApp);
            thread.start();
   }

private void createDirectory(String dirName) {
    File newDir = new File("D:\\"+dirName);
    if(!newDir.exists()){
        boolean isCreated = newDir.mkdir();
    }
 }
} 

Y este es el código del Cliente que se ejecuta en el hilo y después de unos minutos captura la captura de pantalla de la pantalla del usuario.

package com.viremp.client;

import java.awt.AWTException;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.Socket;
import java.util.Random;

import javax.imageio.ImageIO;

public class ClientApp implements Runnable {
    private static long nextTime = 0;
    private static ClientApp clientApp = null;
    private String serverName = "192.168.100.18"; //loop back ip
    private int portNo = 61000;
    //private Socket serverSocket = null;

    /**
     * @param args
     * @throws InterruptedException 
     */
    public static void main(String[] args) throws InterruptedException {
        clientApp = new ClientApp();
        clientApp.getNextFreq();
        Thread thread = new Thread(clientApp);
        thread.start();
    }

    private void getNextFreq() {
        long currentTime = System.currentTimeMillis();
        Random random = new Random();
        long value = random.nextInt(180000); //1800000
        nextTime = currentTime + value;
        //return currentTime+value;
    }

    @Override
    public void run() {
        while(true){
            if(nextTime < System.currentTimeMillis()){
                System.out.println(" get screen shot ");
                try {
                    clientApp.sendScreen();
                    clientApp.getNextFreq();
                } catch (AWTException e) {
                    // TODO Auto-generated catch block
                    System.out.println(" err"+e);
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch(Exception e){
                    e.printStackTrace();
                }

            }
            //System.out.println(" statrted ....");
        }

    }

    private void sendScreen()throws AWTException, IOException {
           Socket serverSocket = new Socket(serverName, portNo);
             Toolkit toolkit = Toolkit.getDefaultToolkit();
             Dimension dimensions = toolkit.getScreenSize();
                 Robot robot = new Robot();  // Robot class 
                 BufferedImage screenshot = robot.createScreenCapture(new Rectangle(dimensions));
                 ImageIO.write(screenshot,"png",serverSocket.getOutputStream());
                 serverSocket.close();
    }
}

Toolkit devuelve píxeles basados ​​en PPI, como resultado, no se crea una captura de pantalla para toda la pantalla cuando se utiliza PPI> 100% en Windows. Propongo hacer esto:

DisplayMode displayMode = GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices()[0].getDisplayMode();
Rectangle screenRectangle = new Rectangle(displayMode.getWidth(), displayMode.getHeight());
BufferedImage screenShot = new Robot().createScreenCapture(screenRectangle);