web.config在数据库链接上的运用[转]

没什么用,只是参考xml文件的读取方式

  1        public string GetConnectionString()
  2        {
  3            return (IsExistKey("appSettings", appSettingsKey)) ? ConfigurationManager.AppSettings[appSettingsKey] : string.Empty;
  4        } 
  5
  6        private string GetXmlFileName()
  7        {
  8            return HttpContext.Current.Server.MapPath("~/Web.config");
  9        } 
 10
 11        private XmlDocument GetWebConfig()
 12        {
 13            XmlDocument xmlDoc = new XmlDocument();
 14            xmlDoc.Load(GetXmlFileName());
 15            return xmlDoc;
 16        } 
 17
 18        public bool IsExistNode(string strNode)
 19        {
 20            XmlDocument xmlDoc = GetWebConfig();
 21            XmlNode xmlNode = xmlDoc.SelectSingleNode(@"/" + strNode); 
 22
 23            // retrieve the appSettings xmlNode   
 24            xmlNode = xmlDoc.SelectSingleNode("//" + strNode);
 25            return (xmlNode != null);
 26        } 
 27
 28        public bool IsExistKey(string strNodeName, string strKey)
 29        {
 30            XmlDocument xmlDoc = GetWebConfig();
 31            bool IsExist = false; 
 32
 33            //在当前所有节点中循环查找
 34            XmlNodeList topM = xmlDoc.DocumentElement.ChildNodes;
 35            foreach (XmlElement element in topM)
 36            {
 37                //判断是否存在节点
 38                if (element.Name == strNodeName)
 39                {
 40                    XmlNodeList node = element.ChildNodes;
 41                    //判断是否存在定义的信息
 42                    if (node.Count > 0)
 43                    {
 44                        //在子节点中循环查找
 45                        foreach (XmlElement el in node)
 46                        {
 47                            //判断Key是否等于所需信息Liumm
 48                            IsExist = (el.Attributes["key"].InnerXml == strKey);
 49                            if (IsExist) break;
 50                        }
 51                    }
 52                }
 53            }
 54            return IsExist;
 55        } 
 56
 57        public void SetValue(string key, string value)
 58        {
 59            XmlDocument xmlDoc = GetWebConfig();
 60            XmlNode xmlNode = xmlDoc.SelectSingleNode(@"/appSettings"); 
 61
 62            // retrieve the appSettings xmlNode   
 63            xmlNode = xmlDoc.SelectSingleNode("//appSettings");
 64            if (xmlNode == null)
 65            {
 66                throw new InvalidOperationException("appSettings section not found");
 67            }
 68            try
 69            {
 70                // XPath select setting "add" element that contains this key       
 71                XmlElement addElem = (XmlElement)xmlNode.SelectSingleNode("//add[@key='" + key + "']");
 72                if (addElem != null)
 73                {
 74                    addElem.SetAttribute("value", value);
 75                }
 76                // not found, so we need to add the element, key and value   
 77                else
 78                {
 79                    XmlElement entry = xmlDoc.CreateElement("add");
 80                    entry.SetAttribute("key", key);
 81                    entry.SetAttribute("value", value);
 82                    xmlNode.AppendChild(entry);
 83                }
 84                //save it   
 85                try
 86                {
 87                    XmlTextWriter writer = new XmlTextWriter(GetXmlFileName(), null);
 88                    writer.Formatting = Formatting.Indented;
 89                    xmlDoc.WriteTo(writer);
 90                    writer.Flush();
 91                    writer.Close();
 92                } 
 93
 94                catch (Exception ex)
 95                {
 96                    throw new Exception(ex.Message);
 97                }
 98            }
 99            catch (Exception ex)
100            {
101                throw new InvalidOperationException(ex.Message);
102            }
103        }
104