.net自定义控件设计期实现

[Designer(typeof(DesignClass))]
    public class UploadFile : Control
    {

     }

 

 

DesignClass.cs 文件

public class DesignClass : System.Web.UI.Design.ControlDesigner
    {
        public override void Initialize(IComponent component)
        {
            base.Initialize(component);

            IWebApplication webApp = (IWebApplication)Component.Site.GetService(typeof(IWebApplication));
            IProjectItem item = webApp.GetProjectItemFromUrl("~/web.config");
            string webConfigPath = item.PhysicalPath;
            WriteConfig(webConfigPath);
        }