HasFile提示未将对象引用设置到对象的实例，怎么解决？

pleasure999 2012-06-13 02:54:33

代码如下：
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data;

public partial class PictureManage_InsertPage : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
userIdValue.Text = Membership.GetUser().ProviderUserKey.ToString();
}
protected void InsertDetailsView_ItemInserting(object sender, DetailsViewInsertEventArgs e)
{
e.Values["userID"]=Membership.GetUser().ProviderUserKey;
e.Values["uploadDate"]=DateTime.Now ;
}
protected void InsertDetailsView_ItemInserted(object sender, DetailsViewInsertedEventArgs e)
{
if (e.AffectedRows > 0)
{
DataView results = (DataView)maxPictureID.Select(DataSourceSelectArguments.Empty );
int PictureAddId = Convert.ToInt16(results[0][0]);
FileUpload imageupload = (FileUpload)InsertDetailsView.FindControl("imageupload");
if (imageupload.HasFile )
{
String path = Server.MapPath("~/Image/");
imageupload.SaveAs(path + PictureAddId + ".jpg");

}
}
}
}

在浏览器中查看结果提示为：

未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。

异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。

源错误:

行 31: int PictureAddId = Convert.ToInt16(results[0][0]);
行 32: FileUpload imageupload = (FileUpload)InsertDetailsView.FindControl("imageupload");
行 33: if (imageupload.HasFile)
行 34: {
行 35: String path = Server.MapPath("~/image/");

源文件: d:\Users\Administrator\Desktop\WebSite2\PictureManage\InsertPage.aspx.cs 行: 33

堆栈跟踪:

[NullReferenceException: 未将对象引用设置到对象的实例。]
PictureManage_InsertPage.InsertDetailsView_ItemInserted(Object sender, DetailsViewInsertedEventArgs e) in d:\Users\Administrator\Desktop\WebSite2\PictureManage\InsertPage.aspx.cs:33
System.Web.UI.WebControls.DetailsView.OnItemInserted(DetailsViewInsertedEventArgs e) +78
System.Web.UI.WebControls.DetailsView.HandleInsertCallback(Int32 affectedRows, Exception ex) +69
System.Web.UI.DataSourceView.Insert(IDictionary values, DataSourceViewOperationCallback callback) +130
System.Web.UI.WebControls.DetailsView.HandleInsert(String commandArg, Boolean causesValidation) +278
System.Web.UI.WebControls.DetailsView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup) +632
System.Web.UI.WebControls.DetailsView.OnBubbleEvent(Object source, EventArgs e) +88
System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
System.Web.UI.WebControls.DetailsViewRow.OnBubbleEvent(Object source, EventArgs e) +113
System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +88
System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +156
System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +168
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2863

不知哪位高手能解释为什么出错？在另外一个程序下调试时可以运行成功的

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