主要使用的是java.util.Robot类来捕获屏幕,可以实现对屏幕一个矩形区域的捕获,通过这个类,我们也可以实现一个远程桌面控制的程序

 

package com.qiu.util;
import java.io.*;
import java.net.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.imageio.*;
import java.io.*;

/**@Author Qiu_BaiChao
 *一个简单的屏幕抓图
 *
 **/
 
public class ScreenCapture {
 //test main
 public static void main(String[] args) throws Exception{
  String userdir = System.getProperty("user.dir");
  File tempFile = new File("d:","temp.png");
  ScreenCapture capture = ScreenCapture.getInstance();
  capture.captureImage();  
  JFrame frame = new JFrame();
  JPanel panel = new JPanel();
  panel.setLayout(new BorderLayout());
  JLabel imagebox = new JLabel();
  panel.add(BorderLayout.CENTER,imagebox);  
  imagebox.setIcon(capture.getPickedIcon());
  capture.saveToFile(tempFile);
  capture.captureImage();
  imagebox.setIcon(capture.getPickedIcon());
  frame.setContentPane(panel);
  frame.setSize(400,300);
  frame.show();
  System.out.println("Over");
 }
 
 private ScreenCapture() {
  
  try{
   robot = new Robot();
  }
  catch(AWTException e) {
   System.err.println("Internal Error: " + e);
   e.printStackTrace();
  }  
  JPanel cp = (JPanel)dialog.getContentPane();
  cp.setLayout(new BorderLayout());  
  labFullScreenImage.addMouseListener(new MouseAdapter() {
    public void mouseReleased(MouseEvent evn) {
      isFirstPoint = true;
      pickedImage = fullScreenImage.getSubimage(recX,recY,recW,recH);
      dialog.setVisible(false);     
    }
   });
   
  labFullScreenImage.addMouseMotionListener(new MouseMotionAdapter() {
    public void mouseDragged(MouseEvent evn) {
     if(isFirstPoint) {
      x1 = evn.getX();
      y1 = evn.getY();
      isFirstPoint = false;  
     }
     else {
      x2 = evn.getX();
      y2 = evn.getY();
      int maxX = Math.max(x1,x2);
      int maxY = Math.max(y1,y2);
      int minX = Math.min(x1,x2);
      int minY = Math.min(y1,y2);
      recX = minX;
      recY = minY;
      recW = maxX-minX;
      recH = maxY-minY;
      labFullScreenImage.drawRectangle(recX,recY,recW,recH);    
     }
    }
    
    public void mouseMoved(MouseEvent e) {
     labFullScreenImage.drawCross(e.getX(),e.getY());
    }
   });
   
  cp.add(BorderLayout.CENTER,labFullScreenImage);
  dialog.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
  dialog.setAlwaysOnTop(true);
  dialog.setMaximumSize(
   Toolkit.getDefaultToolkit().getScreenSize());
  dialog.setUndecorated(true);
  dialog.setSize(dialog.getMaximumSize());
  dialog.setModal(true);
 }
 //Singleton Pattern
 public static ScreenCapture getInstance() {
  return defaultCapturer;
 }
 /**捕捉全屏慕*/
 public Icon captureFullScreen() {
  fullScreenImage = robot.createScreenCapture(new Rectangle(
   Toolkit.getDefaultToolkit().getScreenSize()));
  ImageIcon icon = new ImageIcon(fullScreenImage);
  return icon;
 }
 /**捕捉屏幕的一个矫形区域
  */
 public void captureImage() {
  fullScreenImage = robot.createScreenCapture(new Rectangle(
   Toolkit.getDefaultToolkit().getScreenSize()));
  ImageIcon icon = new ImageIcon(fullScreenImage);
  labFullScreenImage.setIcon(icon);  
  dialog.setVisible(true); 
 }
 /**得到捕捉后的BufferedImage*/ 
 public BufferedImage getPickedImage() {
  return pickedImage;
 }
 /**得到捕捉后的Icon*/ 
 public ImageIcon getPickedIcon() {
  return new ImageIcon(getPickedImage());
 }
 /**储存为一个文件,为PNG格式
  *@deprecated
  *replaced by saveAsPNG(File file)
  **/
 @Deprecated
 public void saveToFile(File file) throws IOException{
  ImageIO.write(getPickedImage(),defaultImageFormater,file);
 }
 /**储存为一个文件,为PNG格式*/
 public void saveAsPNG(File file) throws IOException {
  ImageIO.write(getPickedImage(),"png",file);
 }
 /**储存为一个JPEG格式图像文件*/
 public void saveAsJPEG(File file) throws IOException {
  ImageIO.write(getPickedImage(),"JPEG",file);
 }
 
 /**写入一个OutputStream*/
 public void write(OutputStream out) throws IOException{
  ImageIO.write(getPickedImage(),defaultImageFormater,out);
 }
 
 //singleton design pattern
 private static ScreenCapture defaultCapturer = new ScreenCapture(); 
 private int x1,y1,x2,y2;
 private int recX,recY,recH,recW; //截取的图像
 private boolean isFirstPoint  = true;
 private BackgroundImage labFullScreenImage = new BackgroundImage();
 private Robot robot;
 private BufferedImage fullScreenImage;
 private BufferedImage pickedImage;
 private String defaultImageFormater = "png";
 private JDialog dialog = new JDialog();
}

/**显示图片的Label*/
class BackgroundImage extends JLabel{
 public void paintComponent(Graphics g) {
  super.paintComponent(g);
  g.drawRect(x,y,w,h);
  String area = Integer.toString(w)+" * "+ Integer.toString(h);
  g.drawString(area,x+(int)w/2-15,y+(int)h/2);
  g.drawLine(lineX,0,lineX,getHeight());
  g.drawLine(0,lineY,getWidth(),lineY);
 }
 
 public void drawRectangle(int x,int y,int width,int height) {
  this.x = x;
  this.y = y;
  h = height;
  w = width;
  repaint();
 }
 
 public void drawCross(int x,int y) {
  lineX = x;
  lineY = y;
  repaint();
 }
 
 int lineX,lineY;
 int x,y,h,w;
}