/// <summary>

 /// 特殊字符转义

 /// </summary>

 /// <param name="xml"></param>

 /// <returns></returns>

 public string XmlCharacterEscaping(string xml)

 {

     string xmlNew = xml;

     if (xml.IndexOf("&") != -)

     {

         xmlNew = xml.Replace("&", "&amp;");

     }

     if (xml.IndexOf("<") != -)

     {

         xmlNew = xml.Replace("<", "&lt;");

     }

     if (xml.IndexOf(">") != -)

     {

         xmlNew = xml.Replace(">", "&gt;");

     }

     if (xml.IndexOf('"') != -)

     {

         char c = '"';

         xmlNew = xml.Replace(c.ToString(), "&quot;");

     }
     return xmlNew;

 }