得到电脑的屏幕截图

public static String capScreenSnapshot()  {    String outFileName = "";    try    {      File f = new File(str);      if (!(f.exists())) {        f.mkdir();      }      outFileName = formatDate(Calendar.getInstance().getTime(),         "yyyy_MM_dd_HH_mm_ss_SSS") + ".jpg";      Toolkit toolkit = Toolkit.getDefaultToolkit();      Dimension screenSize = toolkit.getScreenSize();      Rectangle screenRect = new Rectangle(screenSize);      Robot robot = new Robot();      BufferedImage image = robot.createScreenCapture(screenRect);      ImageIO.write(image, "jpeg", new File(outFileName));      System.out.println("保存屏幕截图 \"" + outFileName + "\".");    }    catch (Exception e) {      e.printStackTrace();    }    return outFileName;  }