ASP.NET FileUpload:如何在选择文件后自动回发？

<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="Button1" runat="server" Text="上传" OnClick="Button1_Click" />

protected void Button1_Click(object sender, EventArgs e)
{
    if (FileUpload1.HasFile)
    {
        string fileName = Path.GetFileName(FileUpload1.FileName);
        FileUpload1.SaveAs(Server.MapPath("~/") + fileName);
        // 处理文件上传后的逻辑
    }
}

    $(document).ready(function () {
        $("#<%=FileUpload1.ClientID%>").on("change", function () {
            var formData = new FormData();
            formData.append("file", $("#<%=FileUpload1.ClientID%>")[0].files[0]);
            $.ajax({
                url: "upload.ashx",
                type: "POST",
                data: formData,
                contentType: false,
                processData: false,
                success: function (response) {
                    // 处理文件上传后的逻辑
                },
                error: function (error) {
                    // 处理错误
                }
            });
        });
    });
</script>