对config文件中的配置进行新增修改删除读取操作

using  System;

using  System.Configuration;

using  System.Reflection;

using  System.Web;

using  System.Xml;

public   enum  ConfigFileType

{

    WebConfig,

    AppConfig

}

namespace  WebApplication1

{

    /// <summary>

    /// Summary description for ReadWriteConfig.

    /// </summary>

    public class ReadWriteConfig

{        

        public string docName = String.Empty; 

        private XmlNode node=null;    

        private int _configType;  

        public int ConfigType

{

            get

{ return _configType; }

            set

{ _configType=value; }

        }  

        SetValue#region SetValue

        public bool SetValue(string key, string value)

{

            XmlDocument cfgDoc = new XmlDocument();

            loadConfigDoc(cfgDoc);   

            // retrieve the appSettings node   

            node =  cfgDoc.SelectSingleNode("//appSettings");      

            if( node == null )

{

                throw new InvalidOperationException( "appSettings section not found");

            }     

            try  

{   

                // XPath select setting "add" element that contains this key       

                XmlElement addElem= (XmlElement)node.SelectSingleNode("//add[@key='" +key +"']") ;

                if(addElem!=null)

{

                    addElem.SetAttribute("value",value);

                }    

                // not found, so we need to add the element, key and value   

                else

{

                    XmlElement entry = cfgDoc.CreateElement("add");

                    entry.SetAttribute("key",key);    

                    entry.SetAttribute("value",value);    

                    node.AppendChild(entry);

                }   

                //save it   

                saveConfigDoc(cfgDoc,docName);   

                return true;  

            }  

            catch

{

                return false;

            } 

        }  

        #endregion

        saveConfigDoc#region saveConfigDoc

        private void saveConfigDoc(XmlDocument cfgDoc,string cfgDocPath)

{

            try

{

                XmlTextWriter writer = new XmlTextWriter( cfgDocPath , null ); 

                writer.Formatting = Formatting.Indented;    

                cfgDoc.WriteTo( writer );    

                writer.Flush(); 

                writer.Close();  

                return;

            }  

            catch

{

                throw;

            }

        } 

        #endregion

        removeElement#region removeElement

        public bool removeElement (string elementKey) 

{ 

            try  

{   

                XmlDocument cfgDoc = new XmlDocument(); 

                loadConfigDoc(cfgDoc);  

                // retrieve the appSettings node  

                node =  cfgDoc.SelectSingleNode("//appSettings");   

                if( node == null )

{

                    throw new InvalidOperationException( "appSettings section not found");

                }     

                // XPath select setting "add" element that contains this key to remove      

                node.RemoveChild( node.SelectSingleNode("//add[@key='" +elementKey +"']") ); 

                saveConfigDoc(cfgDoc,docName);  

                return true; 

            } 

            catch

{

                return false;

            } 

        }        

        #endregion

        modifyElement#region modifyElement

        public bool modifyElement (string elementKey) 

{ 

            try  

{   

                XmlDocument cfgDoc = new XmlDocument(); 

                loadConfigDoc(cfgDoc);  

                // retrieve the appSettings node  

                node =  cfgDoc.SelectSingleNode("//appSettings");   

                if( node == null )

{

                    throw new InvalidOperationException( "appSettings section not found");

                }     

                // XPath select setting "add" element that contains this key to remove      

                node.RemoveChild(node.SelectSingleNode("//add[@key='" +elementKey +"']")); 

                saveConfigDoc(cfgDoc,docName);  

                return true; 

            } 

            catch

{

                return false;

            } 

        }        

        #endregion

        loadConfigDoc#region loadConfigDoc

        private XmlDocument loadConfigDoc( XmlDocument cfgDoc ) 

{   

            // load the config file   

            if(  Convert.ToInt32(ConfigType)==Convert.ToInt32(ConfigFileType.AppConfig))

{

                docName= ((Assembly.GetEntryAssembly()).GetName()).Name;   

                docName +=   ".exe.config";

            } 

            else

{

                docName=HttpContext.Current.Server.MapPath("web.config");

            }  

            cfgDoc.Load( docName );  

            return cfgDoc;

        } 

        #endregion

    }

}