Java捕获当前屏幕图像

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　import Java.awt.*;
import java.awt.image.*;
import com.sun.image.codec.jpeg.*;
class ImageCanvas extends Canvas{
private Image image;
private Dimension prefSize;
public ImageCanvas(Image image){
this.image = image;
calculatePreferredSize();
}
public void setImage(Image image){
this.image = image;
calculatePreferredSize();
repaint();
}
private void calculatePreferredSize(){
prefSize = new Dimension(image.getWidth(this),image.getHeight(this));
System.out.println(image.getWidth(this));
setSize(prefSize);
}
public Dimension getPreferredSize() {
return prefSize;
}
public Dimension getMinimumSize() {
return prefSize;
}
public void update(Graphics g){
paint(g);
}
public void paint(Graphics g){
g.drawImage(image,0,0,null);
}
}
class ImageUtils{
public static Image getScreenImage(){
Robot robot;
try {
robot = new Robot();
}catch(Exception e) {
throw new RuntimeException("unable to constrUCt Robot");
}
Dimension screenDims =Toolkit.getDefaultToolkit().getScreenSize();
Image screen =robot.createScreenCapture(new Rectangle(450,350,screenDims.width,screenDims.height)).getScaledInstance(400,300,Image.SCALE_SMOOTH);
MediaTracker tracker =new MediaTracker(new Label());
tracker.addImage(screen,1);
try {
tracker.waitForID(0);
}catch(InterruptedException e) { /** ... */ }
return screen;
}
}
public class ScreenCapture extends Frame{
private ImageCanvas canvas =new ImageCanvas(ImageUtils.getScreenImage());
public ScreenCapture(){
add(canvas);
setSize(400,300);
setVisible(true);
Thread imageThread =new UpdateThread();
imageThread.setDaemon(true);
imageThread.start();
}
class UpdateThread extends Thread{
public void run(){
while(true){
try {
Thread.currentThread().sleep(1000);
}
catch (Exception ex) {
}
canvas.setImage(ImageUtils.getScreenImage());
validate();
}
}
}
public static void main(String[] args){
new ScreenCapture();
}
}