FileUpload在頁面刷新上傳不需要的文件

我正在使用asp.net C＃FIleUpload。我面臨一個問題，那就是當我上傳一張圖片並將其存儲在指定的文件夾中時，刷新頁面後圖片會再次上載多次，因爲頁面已刷新。我嘗試啓用和禁用ViewState選項，但同樣的問題仍然存在。當我上傳圖片時，我已經編寫了我的功能，它將立即得到一個唯一的名稱，所以圖片不會被覆蓋。任何人都可以解釋如何控制這種行爲，以便圖片只上傳到指定的上傳按鈕上，而不是刷新頁面。下面是我使用的主要代碼：FileUpload在頁面刷新上傳不需要的文件

protected void btnUpload_Click(object sender, EventArgs e) 
{ 

if ((Session["Img1"] != null) && (Session["Img2"] != null) && (Session["Img3"] != null) && (Session["Img4"] != null)) 
    { 
     lblUploadMsg.Text = "You cannot upload more than 4 pictures"; 
     return; 
    } 
    if (FileUpload1.HasFile) 
    { 
     string fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName); 
     if (fileExtension.ToLower() == ".jpg") 
     { 
      int fileSize = FileUpload1.PostedFile.ContentLength; 

      if (FileUpload1.PostedFile.ContentLength < 2097152) 
      { 

       //FileUpload1.SaveAs(Server.MapPath("~/Temp/" + FileUpload1.FileName)); 
       //Response.Write("Successfully Done"); 

       string sp = Server.MapPath("~/ItemPictures/"); 
       String fn = Guid.NewGuid().ToString() + FileUpload1.FileName.Substring(FileUpload1.FileName.LastIndexOf(".")); 
       if (sp.EndsWith("\\") == false) 
        sp += "\\"; 
       sp += fn; 
       FileUpload1.PostedFile.SaveAs(sp); 
       lblUploadMsg.ForeColor = System.Drawing.Color.Green; 
       lblUploadMsg.Text = "Picture Uploaded succefully. You can upload upto 4 pictures"; 
       Aziz.InnerHtml += "Image saved\n"; 

       if (Session["Img1"] == null) 
       { 
        Session["Img1"] = "~/ItemPictures/" + fn; 
       } 
       else if (Session["Img2"] == null) 
       { 
        Session["Img2"] = "~/ItemPictures/" + fn; 
       } 
       else if (Session["Img3"] == null) 
       { 
        Session["Img3"] = "~/ItemPictures/" + fn; 
       } 
       else if (Session["Img4"] == null) 
       { 
        Session["Img4"] = "~/ItemPictures/" + fn; 
       } 
      } 
      else 
      { 
       lblUploadMsg.Text = "Maximum 2MB files are allowed"; 
      } 
     } 
     else 
     { 
      lblUploadMsg.Text = "Only JPG files are allowed"; 
     } 
    } 
    else 
    { 
     lblUploadMsg.Text = "No File was Selected"; 
    } 
    ShowAvailblImgs(); 
    } 

    private void ShowAvailblImgs() 
    { 
    if (Session["Img1"] != null) 
    { 
     Image1.ImageUrl = (string)Session["img1"]; 
     Image1.Width = 130; 
     Image1.Height = 130; 
     Image1.Visible = true; 
    } 
    else 
     Image1.Visible = false; 
    if (Session["Img2"] != null) 
    { 
     Image2.ImageUrl = (string)Session["img2"]; 
     Image2.Width = 130; 
     Image2.Height = 130; 
     Image2.Visible = true; 
    } 
    else 
     Image2.Visible = false; 
    if (Session["Img3"] != null) 
    { 
     Image3.ImageUrl = (string)Session["img3"]; 
     Image3.Width = 130; 
     Image3.Height = 130; 
     Image3.Visible = true; 
    } 
    else 
     Image3.Visible = false; 
    if (Session["Img4"] != null) 
    { 
     Image4.ImageUrl = (string)Session["img4"]; 
     Image4.Width = 130; 
     Image4.Height = 130; 
     Image4.Visible = true; 
    } 
    else 
     Image4.Visible = false; 
}

來源

2013-07-31 user2599269

您可以保留上傳文件的MD5校驗和緩存。對於新上傳，請檢查上傳文件的MD5。您還可以在頁面的隱藏字段中添加令牌。如果在緩存中未找到提交的令牌，則可以保存圖像。如果找到了，用戶已經提交了一個文件。在成功上傳時，用戶需要一個新的令牌。 – Amy

感謝您的推薦。如果有人知道，我還在尋找其他建議。 – user2599269

如果您使用的是' –