C# AsyncFileUpload双上传

我正在尝试使用AsyncFileUpload和按钮上载图像。下面是我用来做这件事的代码。但它不确定如何让它只在点击btnUpload后上传图像。当前的问题是，一旦我在asyncfileupload控件中浏览了我想要的图像，就会有一个loading.gif显示它正在加载，并且我刷新页面，而没有单击BTNUP将已经上载到数据库中的图像加载。我想做的是在点击btnUpload后让图像上传。一定要帮助解决这个问题。谢谢

标记代码：

<script type="text/javascript" language="javascript">
    function StartUpload(sender, args) {
        var filename = args.get_fileName();
        var path = args.get_path();
        if (filename != "") {
            // code to get File Extension..
            var arr1 = new Array;
            arr1 = filename.split("\\");
            var len = arr1.length;
            var img1 = arr1[len - 1];
            var filext = img1.substring(img1.lastIndexOf(".") + 1);


            // Checking Extension
            if (filext == "jpg" || filext == "JPG") {
                $get("<%=lblUpload.ClientID %>").innerHTML = "";
                $get("<%=btnUpload.ClientID %>").disabled = false;
                return true;
            }
            else {
                $get("<%=lblUpload.ClientID %>").innerHTML = "Only .jpg and .JPG image allowed.";
                $get("<%=btnUpload.ClientID %>").setAttribute('disabled', 'disabled');
                return false;
            }
        }
    }

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我想只要去掉下面的线就可以了

OnUploadedComplete="btnUpload_Click"

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请告诉我它是否有效…

我认为您没有按照预期的方式使用AyncFileUpload控件。该控件用于在自动选择文件后上载文件。对于“上传”按钮来说，更正确的术语应该是“保存”，因为文件已经存在于服务器上，只需要保存即可

通过调用onPloadedComplete，您实际上是在调用代码来保存文件。发件人：

UploadedComplete—文件成功加载时在服务器端激发 上传

正如Alicina建议的，您应该删除此呼叫，因为它似乎是多余的

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如果您只希望在单击“上载”按钮后上载文件，则需要调查其他控件。您可能希望查看其他上载控件，如或ASP.net中的标准文件上载控件[尽管我不太确定这对更新面板的效果如何].

当您希望用户单击按钮时，为什么还要异步文件上载？如果您希望它是异步的，那么单击按钮并上载完成的事件就是接受上载。不上传抱歉，我没有在updatepanel中添加触发器，这就是它不工作的原因。

protected void btnUpload_Click(object sender, EventArgs e)
    {
        if (AsyncFileUpload1.HasFile == true)
        {
            String nric = (String)Session["nric"];

            string filePath = AsyncFileUpload1.PostedFile.FileName;
            string filename = Path.GetFileName(filePath);
            string ext = Path.GetExtension(filename);

            string contenttype = String.Empty;

            switch (ext)
            {
                case ".jpg":
                    contenttype = "image/jpg";
                    break;

                case ".JPG":
                    contenttype = "image/jpg";
                    break;
            }
            if (contenttype != String.Empty)
            {
                System.Drawing.Image uploaded = System.Drawing.Image.FromStream(AsyncFileUpload1.PostedFile.InputStream);

                System.Drawing.Image newImage = new Bitmap(1024, 768);
                using (Graphics g = Graphics.FromImage(newImage))
                {
                    g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    g.DrawImage(uploaded, 0, 0, 1024, 768);
                }

                byte[] results;
                using (MemoryStream ms = new MemoryStream())
                {
                    ImageCodecInfo codec = ImageCodecInfo.GetImageEncoders().FirstOrDefault(c => c.FormatID == ImageFormat.Jpeg.Guid);
                    EncoderParameters jpegParms = new EncoderParameters(1);
                    jpegParms.Param[0] = new EncoderParameter(Encoder.Quality, 95L);
                    newImage.Save(ms, codec, jpegParms);
                    results = ms.ToArray();

                }

                //insert the file into database
                string strQuery = "Update MemberAccount Set profilepicture = @Data Where nric = @Nric";
                SqlCommand cmd = new SqlCommand(strQuery);

                cmd.Parameters.Add("@Nric", SqlDbType.VarChar).Value = nric;

                cmd.Parameters.AddWithValue("@Data", results);

                InsertUpdateData(cmd);

                UpdatePanel2.Update();                    

                lblUpload.ForeColor = System.Drawing.Color.Green;
                lblUpload.Text = "Profile Picture Updated.";
            }
        }
    }

OnUploadedComplete="btnUpload_Click"