import java.awt.AWTException;  import java.awt.Color;  import java.awt.Dimension;  import java.awt.Graphics;  import java.awt.GraphicsDevice;  import java.awt.GraphicsEnvironment;  import java.awt.Rectangle;  import java.awt.Robot;  import java.awt.Toolkit;  import java.awt.event.KeyAdapter;  import java.awt.event.KeyEvent;  import java.awt.event.MouseAdapter;  import java.awt.event.MouseEvent;  import java.awt.event.MouseMotionAdapter;  import java.awt.image.BufferedImage;  import java.awt.image.RescaleOp;  import java.io.File;  import java.io.IOException;  import java.text.SimpleDateFormat;  import java.util.Date;     import javax.imageio.ImageIO;  import javax.swing.JFrame;  import javax.swing.filechooser.FileSystemView;     /**   * java截屏   * 运行后将当前屏幕截取，并最大化显示。   * 拖拽鼠标，选择自己需要的部分。   * 按Esc键保存图片到桌面，并退出程序。   * 点击右上角（没有可见的按钮），退出程序，不保存图片。   *    * @author JinCeon   */  public class SnapshotTest {      public static void main(String[] args) {          // 全屏运行          RectD rd = new RectD();          GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment()                  .getDefaultScreenDevice();          gd.setFullScreenWindow(rd);      }  }     class RectD extends JFrame {      private static final long serialVersionUID = 1L;      int orgx, orgy, endx, endy;      Dimension d = Toolkit.getDefaultToolkit().getScreenSize();      BufferedImage image;      BufferedImage tempImage;      BufferedImage saveImage;      Graphics g;         @Override      public void paint(Graphics g) {          RescaleOp ro = new RescaleOp(0.8f, 0, null);          tempImage = ro.filter(image, null);          g.drawImage(tempImage, 0, 0, this);      }         public RectD() {          snapshot();          setVisible(true);          // setSize(d);//最大化窗口          setDefaultCloseOperation(EXIT_ON_CLOSE);          this.addMouseListener(new MouseAdapter() {              public void mousePressed(MouseEvent e) {                  orgx = e.getX();                  orgy = e.getY();              }          });          this.addMouseMotionListener(new MouseMotionAdapter() {              public void mouseDragged(MouseEvent e) {                  endx = e.getX();                  endy = e.getY();                  g = getGraphics();                  g.drawImage(tempImage, 0, 0, RectD.this);                  int x = Math.min(orgx, endx);                  int y = Math.min(orgy, endy);                  int width = Math.abs(endx - orgx)+1;                  int height = Math.abs(endy - orgy)+1;                  // 加上1，防止width或height为0                  g.setColor(Color.BLUE);                  g.drawRect(x-1, y-1, width+1, height+1);                  //减1，加1都是为了防止图片将矩形框覆盖掉                  saveImage = image.getSubimage(x, y, width, height);                  g.drawImage(saveImage, x, y, RectD.this);              }          });          this.addKeyListener(new KeyAdapter() {              @Override              public void keyReleased(KeyEvent e) {                  // 按Esc键退出                  if (e.getKeyCode() == 27) {                      saveToFile();                      System.exit(0);                  }              }          });      }         public void saveToFile() {          SimpleDateFormat sdf = new SimpleDateFormat("yyyymmddHHmmss");          String name = sdf.format(new Date());          File path = FileSystemView.getFileSystemView().getHomeDirectory();          String format = "jpg";          File f = new File(path + File.separator + name + "." + format);          try {              ImageIO.write(saveImage, format, f);          } catch (IOException e) {              e.printStackTrace();          }      }         public void snapshot() {          try {              Robot robot = new Robot();              Dimension d = Toolkit.getDefaultToolkit().getScreenSize();              image = robot.createScreenCapture(new Rectangle(0, 0, d.width,                      d.height));          } catch (AWTException e) {              e.printStackTrace();          }      }  }