源代码主要使用的是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;
}