[.Net C#]圖片上傳預覽

這邊來教大家做個資料庫式的網頁留言版系統
 首先在網頁中加入UpdatePanel及Image元件

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
 <contenttemplate>
  <asp:image height="100px" id="previewImg" runat="server" visible="false" width="100px" />
 </contenttemplate>
</asp:updatepanel>

接著在圖片上傳事件寫入

if (Image_Upload.HasFile)
 {
   String FileName = Image_Upload.FileName;
   String savePath = Server.MapPath("~/UploadImage/" + FileName);
   Image_Upload.SaveAs(savePath);
   String ImgFormat =Image_Upload.FileName.Split('.')[(Image_Upload.FileName.Split('.')).Length - 1].ToUpper();
   String FileName = Image_Upload.FileName;
   String savePath = Server.MapPath("~/UploadImage/" + FileName);
   Image_Upload.SaveAs(savePath);
   if (previewImg.ImageUrl == "")
     {
       previewImg.ImageUrl = "Server端位置/UploadImage/" + FileName;
       Image.DataBind();
     }
}

這樣就會在previewImg中顯示出預覽圖~
不過當然此方法是已經把圖片上傳至伺服器中了