JXL取日期时yy-mm-dd 转成yyyy-mm-dd

	private static String getCellTypeForDate(Cell   cellObject) {
		  String dateStr="";
		  if(cellObject.getType()==CellType.DATE){
			  DateCell   cellValue   =   (DateCell)cellObject;  
			  Date   dt   =   cellValue.getDate();  
			  SimpleDateFormat   formatter   =   new   SimpleDateFormat("yyyy-MM-dd");  
			  dateStr   =   formatter.format(dt);  
		  }
		  return dateStr;
	}