字符串转义成XML

public static string XmlEscape(string unescaped){    Xmldocument doc = new Xmldocument();    XmlNode node = doc.CreateElement("root");    node.InnerText = unescaped;    return node.InnerXml;}public static string XmlUnescape(string escaped){    Xmldocument doc = new Xmldocument();    XmlNode node = doc.CreateElement("root");    node.InnerXml = escaped;    return node.InnerText;}