1、 <add key="FileSize" value="419430400" />
return ConfigurationManager.AppSettings["FileSize"].ToString();
2、<connectionStrings>
<add name="DataBaseConnString" connectionString="Data Source=.;Initial Catalog=***;Persist Security Info=True;User ID=sa;Password=**" providerName="System.Data.SqlClient"/>
</connectionStrings>
//return ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;