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;
  }