c#配置文件中自定义块节点的方法

  <appSettings>
         <add key="BranchCode" value="FS"/>
  </appSettings>

   private string _defaultBranchCode = ConfigurationManager.AppSettings["BranchCode"].ToString();//运营中心

  <pdd>
    <!--基础域名-->
    <add key="base_uri" value="xxxxxx"/>
    <!--测试环境-->
    <!--拼多多开放平台分配给服务商应用的唯一标示-->
    <add key="target_client_id" value="xxxxxxx"/>
    <!-- 调用拼多多开放平台 client_id-->
    <add key="client_id" value="xxxxxxx"/>
    <!--调用拼多多开放平台 秘钥-->
    <add key="client_secret" value="xxxxxxxxf"/>
  </pdd>
 <configSections>
    <section name="pdd" type="System.Configuration.NameValueSectionHandler"/>
   </configSections>    

  public class pddConfig : IPddConfig
    {
        private string _base_uri;
        private string _target_client_id;
        private string _client_id;
        private string _client_secret;
        public pddConfig()
        {
            try
            {
                var pddConfig = ConfigurationManager.GetSection("pdd") as NameValueCollection;
                _base_uri = pddConfig["base_uri"];
                _target_client_id = pddConfig["target_client_id"];
                _client_id = pddConfig["client_id"];
                _client_secret = pddConfig["client_secret"];
            }
            catch (Exception ex)
            {
                throw new Exception("PDD配置错误, 请检查配置文件", ex);
            }
        }
        public string base_uri { get { return _base_uri; } }
        public string target_client_id { get { return _target_client_id; } }
        public string client_id { get { return _client_id; } }
        public string client_secret { get { return _client_secret; } }
    }
     public interface IPddConfig
    {
        string base_uri { get; }
        string target_client_id { get; }
        string client_id { get; }
        string client_secret { get; }
    }

  builder.RegisterType<pddConfig>().As<IPddConfig>().InstancePerRequest();
  builder.RegisterType<PddService>().As<IPddService>().InstancePerRequest();

    public interface IPddService
    {
    }
    public class PddService : IPddService
    {
        public static string base_uri;
        public static string target_client_id;
        public static string client_id;
        public static string client_secret;
        public readonly IPddConfig _pddConfig;
       public PddService(IPddConfig PddConfig)
        {
            _pddConfig = PddConfig;
            GetConfig();
        }
        public void GetConfig()
        {
            base_uri = _pddConfig.base_uri;
            target_client_id = _pddConfig.target_client_id;
            client_id = _pddConfig.client_id;
            client_secret = _pddConfig.client_secret;
        }
    }

<configuration>
  <configSections>
    <section name="MyCustomSection" type="System.Configuration.NameValueSectionHandler" />
  </configSections>
  <MyCustomSection>
    <add key="Key1" value="Value1" />
    <add key="Key2" value="Value2" />
  </MyCustomSection>
</configuration>

NameValueCollection mySection = ConfigurationManager.GetSection("MyCustomSection") as NameValueCollection;
string value1 = mySection["Key1"];
string value2 = mySection["Key2"];