.NET 配置项扩展

using System;
using System.Configuration;

namespace ConsoleApplication3
{
    /*
        web.config 或 app.config 中的配置示例如下（注：configSections 节一定要是 configuration 节下的第一个元素）：
     
        <?xml version="1.0" encoding="utf-8" ?>
        <configuration>
            <configSections>
                <section name="urls" type="ConsoleApplication3.EasConfigurationSection, ConsoleApplication3"/>
            </configSections>
    
            <urls>
                <url name="cn.bing.com" url="http://cn.bing.com/" port="80"></url>
            </urls>
        </configuration>
     */

    public class EasConfigurationElement : ConfigurationElement
    {
        [ConfigurationProperty("name", IsKey=true, IsRequired=true)]
        public string Name
        {
            get { return (string)this["name"]; }
            set { this["name"] = value; }
        }

        [ConfigurationProperty("url", DefaultValue = "")]
        public string Url
        {
            get { return (string)this["url"]; }
            set { this["url"] = value; }
        }

        [ConfigurationProperty("port", DefaultValue = 0, IsRequired = false)]
        [IntegerValidator(MinValue = 0, MaxValue = 8080, ExcludeRange = false)]
        public int Port
        {
            get { return (int)this["port"]; }
            set { this["port"] = value; }
        }
    }

    [ConfigurationCollection(typeof(EasConfigurationElement))]
    public class EasConfigurationElementCollection : ConfigurationElementCollection
    {
        protected override string ElementName
        {
            get
            {
                return "url";
            }
        }

        public override ConfigurationElementCollectionType CollectionType
        {
            get { return ConfigurationElementCollectionType.BasicMap; }
        }

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

        protected override object GetElementKey( ConfigurationElement element )
        {
            var newElement = element as EasConfigurationElement;

            if( newElement != null ) return newElement.Name;

            throw new NullReferenceException( "element can not convert to " + typeof( EasConfigurationElement ) );
        }

        public EasConfigurationElement this[ int index ]
        {
            get { return (EasConfigurationElement)BaseGet( index ); }
            set
            {
                if( BaseGet( index ) != null )
                {
                    BaseRemoveAt( index );
                }

                BaseAdd( index, value );
            }
        }
    }

    public class EasConfigurationSection : ConfigurationSection
    {
        [ConfigurationProperty("", IsDefaultCollection = true)]
        public EasConfigurationElementCollection Urls
        {
            get
            {
                var collection = (EasConfigurationElementCollection)base[""];

                return collection;
            }
        }
    }
}