在自定义控件的构造函数中保持ViewState状态

在自定义控件的构造函数中保持ViewState状态，（注意：如果不在构造函数中使用ViewState,它是可以保持的，可能是页面的处理问题，待解决）

public class FileUploadControl : System.Web.UI.Control

     {

         public FileUploadControl()

         {

              if(m_FileUploadWebService == null)

              {

                   m_FileUploadWebService = new FileUploadWebService.FileUpload();

                   m_FileUploadWebService.Url = System.Configuration.ConfigurationSettings.AppSettings["UploadWebPage"].ToLower().Replace("default.aspx", "FileUpload.asmx");

              }

              if(this.UploadID == string.Empty)

              {

                   this.UploadID = Guid.NewGuid().ToString("N");

                   m_FileUploadWebService.Initialize(this.UploadID);

              }     

              if(ViewState["Borderss"] == null)

              {

                   this.Borderss = !this.Borderss;

              }

         }

private string UploadID

         {

              set

              {

                   ViewState["UploadID"] = value;

              }

              get

              {

                   if(ViewState["UploadID"] != null)

                   {

                       return ViewState["UploadID"].ToString();

                   }

                   else

                   {

                       return string.Empty;

                   }

              }

         }

-- 重写父类的方法 --#region -- 重写父类的方法 --

          protected override void Render(HtmlTextWriter writer)

         {

              base.Render (writer);

              writer.WriteBeginTag("iframe");

              writer.WriteAttribute("id", this.ClientID);

              writer.WriteAttribute("name", this.UniqueID);

              writer.WriteAttribute("width", "400");

              writer.WriteAttribute("frameborder", "0");

              if(this.Borderss)

              {

                   this.m_Style = this.m_Style.Replace("#000000", this.BorderColor);

                   writer.WriteAttribute("style", this.m_Style);

              }

              writer.WriteAttribute("src", System.Configuration.ConfigurationSettings.AppSettings["UploadWebPage"].Trim() + "?id=" + this.UploadID);

              writer.WriteAttribute("uploadid", this.UploadID);

              writer.Write(">");

              writer.WriteEndTag("iframe");

         }

 

         

          protected override object SaveViewState()

         {             

              // Save State as a cumulative array of objects.

              object BaseViewState = base.SaveViewState();

              object[] AllStates = new object[2];

             AllStates[0] = BaseViewState;

             AllStates[1] = this.UploadID;

              return AllStates;

         }

 

          protected override void LoadViewState(object savedState)

         {

              if (savedState != null)

              {

                   // Load State from the array of objects that was saved at ;

                   // SavedViewState.

                   object[] MyState = (object[])savedState;

                   if (MyState[0] != null)

                   {

                        base.LoadViewState(MyState[0]);

                   }

                   if (MyState[1] != null)

                   {

                        this.UploadID = (string)MyState[1];

                   }

              }

         }

          #endregion

}