实现自己的配置读取器

    [HostProtection(SecurityAction.LinkDemand, MayLeakOnAbort = true)]
    public class AddinSectionHandler : IConfigurationSectionHandler {
        public object Create(object parent, object context, XmlNode section) {
            List<AddinConfigItem> colItems;
            if (parent == null) {
                colItems = new List<AddinConfigItem>();
            }
            else {
                List<AddinConfigItem> colParent = (List<AddinConfigItem>)parent;
                colItems = new List<AddinConfigItem>(colParent);
            }
            AddinConfigItem item;
            foreach (XmlNode nodeItem in section.ChildNodes) {
                item = new AddinConfigItem();
                item.DllFile = nodeItem.Attributes["dllFile"].Value;
                item.AddinClass = nodeItem.Attributes["addinClass"].Value;
                colItems.Add(item);
            }
            return colItems;
        }
    }

    public class AddinConfigItem {
        private string _dllFile;

        public string DllFile {
            get { return _dllFile; }
            set { _dllFile = value; }
        }

        private string _addinClass;

        public string AddinClass {
            get { return _addinClass; }
            set { _addinClass = value; }
        }
    }

配置文件：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 <configSections>
  <section name="Assemblys"
     type="Dcms.Common.AddinSectionHandler,Dcms.Common"/>
 </configSections>
 <Assemblys>
  <Assembly dllFile="a.dll" addinClass="a" />
  <Assembly dllFile="b.dll" addinClass="b" />
 </Assemblys>
</configuration>
参考文章：http://www.codeproject.com/aspnet/ConfigSections.asp