javascript - 在导出期间显示更新进度

Question

单击导出到 Excel 按钮后，使用下面的 Java 脚本显示加载器。

<script type="text/javascript">
    function showProgress() {
        var updateProgress = $get("<%= UpdateProgress1.ClientID %>");
        updateProgress.style.display = "block";
    }
</script>


<asp:Button ID="btntoExcel" runat="server" Text="Export to Excel"  onclick="btntoExcel_Click" OnClientClick="showProgress()" Width="115px" 
                CssClass="styleShowData" Font-Size="Smaller" />

一切正常，但加载器在将文件保存到系统后继续加载。

不知道如何停止加载器，因为在 JS 中它被称为

updateProgress.style.display = " block "

任何建议都会非常有帮助。

提前致谢。

在下方添加完整代码

<%@ Page Language="VB" AutoEventWireup="true" CodeFile="ViewReport.aspx.vb" Inherits="ViewReport" %>

状况报告

    <script type="text/javascript">
        function showProgress() {
            var updateProgress = $get("<%= UpdateProgress1.ClientID %>");
            updateProgress.style.display = "block";
        }

        function hideProgress() {
            var updateProgress = $get("<%= UpdateProgress1.ClientID %>");
            updateProgress.style.display = "none";
        }   
    </script> 

<div runat="server" id="divPopupWindow" align="Left" style="position: relative; top: -11px; left: 0px; background-color: #C8B49B;">
    <marquee behavior="alternate"><asp:Label ID="mqHeader1" runat="server" Text="Scrolling Employee Info"></asp:Label></marquee>

    <br />
        <asp:LoginStatus ID="LoginStatus1" runat="server" />
    <br /><br />

    <asp:UpdatePanel runat="server" ID="UpdatePanel_1">
        <ContentTemplate>

        <div runat="server" id="divMyPageWidth_2" align="Left" style="position: relative; height: 10%; left: 0px; background-color: #C8B49B;">

        <asp:Button ID="btntoExcel" runat="server" Text="Export to Excel"  onclick="btntoExcel_Click" OnClientClick="showProgress()" Width="115px" 
            CssClass="styleShowData" Font-Size="Smaller" />

        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

        <asp:Button ID="btnGotoMainPage" runat="server" Text="Goto Main Page"  
        Width="118px" CssClass="stGotoMainPage" 
        Font-Size="Smaller" />

                <br />
                <table>
                    <tr>
                        <td class="style2">
                            <asp:DropDownList ID="ddlStatusSelection" runat="server">
                                <asp:ListItem Selected="True">Approved</asp:ListItem>
                                <asp:ListItem>Pending</asp:ListItem>
                                <asp:ListItem>Rejected</asp:ListItem>
                            </asp:DropDownList>
                        </td>

                        <td class="style3">
                            <asp:DropDownList ID="ddlShowRecordsCount" runat="server">
                                <asp:ListItem Selected="True">25</asp:ListItem>
                                <asp:ListItem>50</asp:ListItem>
                                <asp:ListItem>100</asp:ListItem>
                                <asp:ListItem>200</asp:ListItem>
                                <asp:ListItem>300</asp:ListItem>
                                <asp:ListItem>400</asp:ListItem>
                                <asp:ListItem>500</asp:ListItem>
                                <asp:ListItem>All</asp:ListItem>
                            </asp:DropDownList>
                        </td>
                        <td>
                            <asp:Button ID="Button1" runat="server" Text="Show Data"  
                            CssClass="styleShowData" />
                        </td>
                    </tr>
            </table>

        <div runat="server" id="divMyPageWidth" align="Left" style="position: relative; background-color: #C8B49B; overflow: scroll">
                <asp:GridView ID="gvScreenToExcel" runat="server" AutoGenerateColumns="false" HeaderStyle-Wrap="True" Height="190px" Width="380px" 
                    BackColor="#DEBA84" BorderColor="#DEBA84" BorderStyle="None" BorderWidth="1px" 
                    RowStyle-Wrap="false"  Font-Size="Small" >
                    <FooterStyle BackColor="#F7DFB5" ForeColor="#8C4510" />
                    <HeaderStyle BackColor="#A55129" Font-Bold="True" ForeColor="White" />
                    <PagerStyle ForeColor="#8C4510" HorizontalAlign="Center" />
                    <RowStyle BackColor="#FFF7E7" ForeColor="#8C4510" />
                    <SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="White" />
                    <SortedAscendingCellStyle BackColor="#FFF1D4" />
                    <SortedAscendingHeaderStyle BackColor="#B95C30" />
                    <SortedDescendingCellStyle BackColor="#F1E5CE" />
                    <SortedDescendingHeaderStyle BackColor="#93451F" />
                    <AlternatingRowStyle BackColor="#FFE7CE" />
                    <Columns>
                        <asp:BoundField DataField="Rec_Num" HeaderText="Record #" />
                        <asp:BoundField DataField="Remarks" HeaderText="Remarks" />
                    </Columns>
                </asp:GridView>
            </div>

        </div>
        </ContentTemplate>

        <Triggers>
            <asp:PostBackTrigger ControlID = "btntoExcel" />
        </Triggers>

    </asp:UpdatePanel>

    <asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel_1">
    <ProgressTemplate>
        <div class="modal">
            <div class="center">
                <img alt="" src="Loader.gif" />
            </div>
            </div>
        </ProgressTemplate>
    </asp:UpdateProgress>
  </div>
</form>

Answer 1

关于此场景的一些事实以及解决方案之前提供的信息:

• 真正的下载应该发生在常规(非异步)回发期间。因此，注册“asp:PostBackTrigger”通常是正确的。否则，Sys.WebForms.PageRequestManagerParserErrorException - what it is and how to avoid it .

• 当 HttpReponse.End 方法(通常/总是export) 参与。

如果严格要求显示自定义进度指示器(而不是在下载期间运行的浏览器进度指示器)，请实现以下解决方案:

• 通过 Sys.WebForms.PageRequestManager 订阅 UpdatePanel 的客户端事件，
• 执行异步请求以显示进度指示器。例如，将“btntoExcel”按钮标记为 asp:AsyncPostBackTrigger。应该会出现进度指示器，
• 单击“btntoExcel”按钮开始例程。处理按钮的 SERVER-SIDE Click 事件并将创建的 EXCEL 文件保存到内存或服务器文件夹，
• 处理客户端 UpdatePanel 的“endRequest”事件。进度指示器应该已经隐藏。向服务器发起真正的回发(例如，通过添加隐藏的“asp:PostBackTrigger”按钮或使用原始的“__doPostBack”函数)，
• 处理此按钮的服务器端单击事件并执行真正的下载(previolsy 创建的文件)。

下面是使用提供的标记测试的完整工作代码:

<script type="text/javascript">
    function showProgress() {
        //var updateProgress = $get("<%= UpdateProgress1.ClientID %>");
        //updateProgress.style.display = "block";
    }
    var prm = Sys.WebForms.PageRequestManager.getInstance();
    prm.add_initializeRequest(prm_InitializeRequest);
    prm.add_endRequest(prm_EndRequest);
    function prm_InitializeRequest(sender, args) {
        alert("Starting Update Panel Async Request... Saving File... Displaying Progress Indicator...");
    }
    function prm_EndRequest(sender, args) {
        alert("Update Panel Async Request Finished. File Saved, But Not Yet Downloaded. Progress Indicator Should Be Already Hidden. Starting Real Download...");
        var btnDoRealDownloadClientObject = $get("<%= btnDoRealDownload.ClientID %>");
        btnDoRealDownloadClientObject.click();
    }
</script>

<asp:UpdatePanel runat="server" ID="UpdatePanel_1">
    <ContentTemplate>
        ...
        <asp:Button ID="btntoExcel" runat="server" Text="Export to Excel" OnClick="btntoExcel_Click" OnClientClick="showProgress()" ... />
        <asp:Button ID="btnDoRealDownload" runat="server" OnClick="btnDoRealDownload_Click" style="display: none" ... />
        ...
    </ContentTemplate>

    <Triggers>
        <%--<asp:PostBackTrigger ControlID="btntoExcel" />--%>
        <asp:AsyncPostBackTrigger ControlID="btntoExcel" />
        <asp:PostBackTrigger ControlID="btnDoRealDownload" />
    </Triggers>

</asp:UpdatePanel>

<asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel_1">
    ...
</asp:UpdateProgress>

//CS
protected void btntoExcel_Click(object sender, EventArgs e) {
    Session["SavedFile"] = SAVE_FILE_AS_MEMORY_STREAM;
    ...
}

protected void btnDoRealDownload_Click(object sender, EventArgs e) {
    MemoryStream stream = Session["SavedFile"] as MemoryStream;
    ...
    Page.Response.BinaryWrite(stream.ToArray());
    Page.Response.End();
}


'VB
Protected Sub btntoExcel_Click(ByVal sender As Object, ByVal e As EventArgs)
    Session("SavedFile") = SAVE_FILE_AS_MEMORY_STREAM
    ...
End Sub

Protected Sub btnDoRealDownload_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim stream As MemoryStream = CType(Session("SavedFile"), MemoryStream)
    ...
    Page.Response.BinaryWrite(stream.ToArray)
    Page.Response.End
End Sub