/// <summary>
 /// 为一个属性指定值
 /// </summary>
 /// <param name="xac"></param>
 /// <param name="strName"></param>
 /// <param name="strValue"></param>
 protected void SetXaValue(XmlAttributeCollection xac, string strName, string strValue)
 {
     for (int i = 0; i < xac.Count; i++)
     {
         if (xac.Item(i).LocalName == strName)
         {
             xac.Item(i).Value = strValue;
             return;
         }
     }
     return;
 }
 /// <summary>
 /// 找到指定名称属性的值
 /// </summary>
 /// <param name="xac"></param>
 /// <param name="strName"></param>
 /// <returns></returns>
 protected string GetXaValue(XmlAttributeCollection xac, string strName)
 {
     for (int i = 0; i < xac.Count; i++)
     {
         if (xac.Item(i).LocalName == strName) return xac.Item(i).Value;
     }
     return null;
 }