对web.config进行增加修改删除的示例

开发时，经常要动态的修改config文件，下面的就是一个实用类。

  1using System;
  2using System.Configuration;
  3using System.Reflection;
  4using System.Web;
  5using System.Xml;
  6public enum ConfigFileType
  7{
  8    WebConfig,
  9    AppConfig
 10}
 11
 12namespace WebApplication1
 13{
 14    /**//// <summary>
 15    /// Summary description for ReadWriteConfig.
 16    /// </summary>
 17    public class ReadWriteConfig
 18    {        
 19        public string docName = String.Empty; 
 20        private XmlNode node=null;    
 21        private int _configType;  
 22        public int ConfigType
 23        {
 24            get{ return _configType; }
 25            set{ _configType=value; }
 26        }  
 27
 28        SetValue#region SetValue
 29        public bool SetValue(string key, string value)
 30        {
 31            XmlDocument cfgDoc = new XmlDocument();
 32            loadConfigDoc(cfgDoc);   
 33            // retrieve the appSettings node   
 34            node =  cfgDoc.SelectSingleNode("//appSettings");      
 35            if( node == null )
 36            {
 37                throw new InvalidOperationException( "appSettings section not found");
 38            }     
 39            try  
 40            {   
 41                // XPath select setting "add" element that contains this key       
 42                XmlElement addElem= (XmlElement)node.SelectSingleNode("//add[@key='" +key +"']") ;
 43                if(addElem!=null)
 44                {
 45                    addElem.SetAttribute("value",value);
 46                }    
 47                // not found, so we need to add the element, key and value   
 48                else
 49                {
 50                    XmlElement entry = cfgDoc.CreateElement("add");
 51                    entry.SetAttribute("key",key);    
 52                    entry.SetAttribute("value",value);    
 53                    node.AppendChild(entry);
 54                }   
 55                //save it   
 56                saveConfigDoc(cfgDoc,docName);   
 57                return true;  
 58            }  
 59            catch
 60            {
 61                return false;
 62            } 
 63        }  
 64        
 65        #endregion
 66
 67        saveConfigDoc#region saveConfigDoc
 68        private void saveConfigDoc(XmlDocument cfgDoc,string cfgDocPath)
 69        {
 70            try
 71            {
 72                XmlTextWriter writer = new XmlTextWriter( cfgDocPath , null ); 
 73                writer.Formatting = Formatting.Indented;    
 74                cfgDoc.WriteTo( writer );    
 75                writer.Flush(); 
 76                writer.Close();  
 77                return;
 78            }  
 79            catch
 80            {
 81                throw;
 82            }
 83        } 
 84        
 85        #endregion
 86
 87        removeElement#region removeElement
 88        public bool removeElement (string elementKey) 
 89        { 
 90            try  
 91            {   
 92                XmlDocument cfgDoc = new XmlDocument(); 
 93                loadConfigDoc(cfgDoc);  
 94                // retrieve the appSettings node  
 95                node =  cfgDoc.SelectSingleNode("//appSettings");   
 96                if( node == null )
 97                {
 98                    throw new InvalidOperationException( "appSettings section not found");
 99                }     
100                // XPath select setting "add" element that contains this key to remove      
101                node.RemoveChild( node.SelectSingleNode("//add[@key='" +elementKey +"']") ); 
102                saveConfigDoc(cfgDoc,docName);  
103                return true; 
104            } 
105            catch
106            {
107                return false;
108            } 
109        }        
110        #endregion
111
112        modifyElement#region modifyElement
113        public bool modifyElement (string elementKey) 
114        { 
115            try  
116            {   
117                XmlDocument cfgDoc = new XmlDocument(); 
118                loadConfigDoc(cfgDoc);  
119                // retrieve the appSettings node  
120                node =  cfgDoc.SelectSingleNode("//appSettings");   
121                if( node == null )
122                {
123                    throw new InvalidOperationException( "appSettings section not found");
124                }     
125                // XPath select setting "add" element that contains this key to remove      
126                node.RemoveChild(node.SelectSingleNode("//add[@key='" +elementKey +"']")); 
127                saveConfigDoc(cfgDoc,docName);  
128                return true; 
129            } 
130            catch
131            {
132                return false;
133            } 
134        }        
135        #endregion
136
137        loadConfigDoc#region loadConfigDoc
138        private XmlDocument loadConfigDoc( XmlDocument cfgDoc ) 
139        {   
140            // load the config file   
141            if(  Convert.ToInt32(ConfigType)==Convert.ToInt32(ConfigFileType.AppConfig))
142            {
143                docName= ((Assembly.GetEntryAssembly()).GetName()).Name;   
144                docName +=   ".exe.config";
145            } 
146            else
147            {
148                docName=HttpContext.Current.Server.MapPath("web.config");
149            }  
150            cfgDoc.Load( docName );  
151            return cfgDoc;
152        } 
153        #endregion
154    }
155}
156