在web.config和app.config文件中增加自定义配置节点的方法

<sectionGroup name="enyim.com"><section name="memcached"
type="Enyim.Caching.Configuration.MemcachedClientSection, Enyim.Caching" /></sectionGroup>

<configSections><section name="log4net" type="System.Configuration.IgnoreSectionHandler"/></configSections>

<?xml version="1.0" encoding="utf-8" ?>
<configuration>  
   <configSections>      
    <section name="SoftwareSettings" type="ImageAssistant.Configuration.SoftwareSettings, ImageAssistant" />  
   </configSections>  
     <SoftwareSettings>    
       <LoadSettings>      
         <add key="LoadBmp" value="true"/>      
         <add key="LoadJpg" value="true"/>      
         <add key="LoadGif" value="true"/>      
         <add key="LoadPng" value="false"/>    
       </LoadSettings>    
     <PathSettings SavePath="C:\ResizeImages\" SearchSubPath="true"/>  
   </SoftwareSettings>  

   <appSettings>    
      <add key="LoadBmp" value="true"/>    
      <add key="LoadJpg" value="true"/>    
      <add key="LoadGif" value="true"/>    
      <add key="LoadPng" value="false"/>   
      <add key="IncludeSubPath"  value="true"/> 
   </appSettings>    
</configuration>

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Configuration; 

namespace ImageAssistant.Configuration 
{ 
    public sealed class LoadSettingsCollection : ConfigurationElementCollection 
    { 
        private IDictionary<string, bool> settings; 

        protected override ConfigurationElement CreateNewElement() 
        { 
            return new LoadSettingsElement(); 
        } 

        protected override object GetElementKey(ConfigurationElement element) 
        { 
            LoadSettingsElement ep = (LoadSettingsElement)element; 

            return ep.Key; 
        } 

        protected override string ElementName 
        { 
            get 
            { 
                return base.ElementName; 
            } 
        } 

        public IDictionary<string, bool> Settings 
        { 
            get 
            { 
                if (settings == null) 
                { 
                    settings = new Dictionary<string, bool>(); 
                    foreach (LoadSettingsElement e in this) 
                    { 
                        settings.Add(e.Key, e.Value); 
                    } 
                } 
                return settings; 
            } 
        } 

        public bool this[string key] 
        { 
            get 
            { 
                bool isLoad = true; 
                if (settings.TryGetValue(key, out isLoad)) 
                { 
                    return isLoad; 
                } 
                else 
                { 
                    throw new ArgumentException("没有对'" + key + "'节点进行配置。"); 
                } 
            } 
        } 

    } 

    public class LoadSettingsElement : ConfigurationElement 
    { 
        [ConfigurationProperty("key", IsRequired = true)] 
        public string Key 
        { 
            get { return (string)base["key"]; } 
            set { base["key"] = value; } 
        } 
        [ConfigurationProperty("value", IsRequired = true)] 
        public bool Value 
        { 
            get { return (bool)base["value"]; } 
            set { base["value"] = value; } 
        } 
    } 

    public class PathSettingElement : ConfigurationElement 
    { 
        /// <summary>  
        ///   
        /// </summary>  
        [ConfigurationProperty("SavePath", IsRequired = true)] 
        public string SavePath 
        { 
            get { return (string)base["SavePath"]; } 
            set { base["SavePath"] = value; } 
        } 
        /// <summary>  
        ///   
        /// </summary>  
        [ConfigurationProperty("SearchSubPath", IsRequired = false, DefaultValue = true)] 
        public bool SearchSubPath 
        { 
            get { return (bool)base["SearchSubPath"]; } 
            set { base["SearchSubPath"] = value; } 
        } 
    } 

    /// <summary>  
    /// 对应config文件中的  
    /// </summary>  
    public sealed class SoftwareSettings : ConfigurationSection 
    { 
        /// <summary>  
        /// 对应SoftwareSettings节点下的LoadSettings子节点  
        /// </summary>  
        [ConfigurationProperty("LoadSettings", IsRequired = true)] 
        public LoadSettingsCollection LoadSettings 
        { 
            get { return (LoadSettingsCollection)base["LoadSettings"]; } 
        } 

        /// <summary>  
        /// 对应SoftwareSettings节点下的PathSettings子节点，非必须  
        /// </summary>  
        [ConfigurationProperty("PathSettings", IsRequired = false)] 
        public PathSettingElement PathSetting 
        { 
            get { return (PathSettingElement)base["PathSettings"]; } 
            set { base["PathSettings"] = value; } 
        } 

    } 
}

class Program 
    { 
        static void Main(string[] args) 
        { 
            SoftwareSettings softSettings = ConfigurationManager.GetSection("SoftwareSettings") as SoftwareSettings; 

            foreach (string key in softSettings.LoadSettings.Settings.Keys) 
            { 
                Console.WriteLine("{0}={1}", key, softSettings.LoadSettings[key]); 
            } 
            Console.WriteLine("SavePath={0},SearchSubPath={1}", softSettings.PathSetting.SavePath, softSettings.PathSetting.SearchSubPath); 
            Console.ReadLine(); 
        } 
    }