一种可能的解决方案是在客户机上使用JavaScript。

客户端算法:

生成一个随机的唯一令牌。 提交下载请求，并在GET/POST字段中包含令牌。 显示“等待”指示灯。 启动一个计时器，每隔一秒左右，查找一个名为“fileDownloadToken”的cookie(或任何您决定的cookie)。 如果cookie存在，并且它的值与令牌匹配，则隐藏“等待”指示器。

服务器算法:

在请求中查找GET/POST字段。 如果它有一个非空值，删除一个cookie(例如。"fileDownloadToken")，并将其值设置为令牌的值。

客户端源代码(JavaScript):

function getCookie( name ) {
  var parts = document.cookie.split(name + "=");
  if (parts.length == 2) return parts.pop().split(";").shift();
}

function expireCookie( cName ) {
    document.cookie = 
        encodeURIComponent(cName) + "=deleted; expires=" + new Date( 0 ).toUTCString();
}

function setCursor( docStyle, buttonStyle ) {
    document.getElementById( "doc" ).style.cursor = docStyle;
    document.getElementById( "button-id" ).style.cursor = buttonStyle;
}

function setFormToken() {
    var downloadToken = new Date().getTime();
    document.getElementById( "downloadToken" ).value = downloadToken;
    return downloadToken;
}

var downloadTimer;
var attempts = 30;

// Prevents double-submits by waiting for a cookie from the server.
function blockResubmit() {
    var downloadToken = setFormToken();
    setCursor( "wait", "wait" );

    downloadTimer = window.setInterval( function() {
        var token = getCookie( "downloadToken" );

        if( (token == downloadToken) || (attempts == 0) ) {
            unblockSubmit();
        }

        attempts--;
    }, 1000 );
}

function unblockSubmit() {
  setCursor( "auto", "pointer" );
  window.clearInterval( downloadTimer );
  expireCookie( "downloadToken" );
  attempts = 30;
}

服务器代码示例(PHP):

$TOKEN = "downloadToken";

// Sets a cookie so that when the download begins the browser can
// unblock the submit button (thus helping to prevent multiple clicks).
// The false parameter allows the cookie to be exposed to JavaScript.
$this->setCookieToken( $TOKEN, $_GET[ $TOKEN ], false );

$result = $this->sendFile();

地点:

public function setCookieToken(
    $cookieName, $cookieValue, $httpOnly = true, $secure = false ) {

    // See: http://stackoverflow.com/a/1459794/59087
    // See: http://shiflett.org/blog/2006/mar/server-name-versus-http-host
    // See: http://stackoverflow.com/a/3290474/59087
    setcookie(
        $cookieName,
        $cookieValue,
        2147483647,            // expires January 1, 2038
        "/",                   // your path
        $_SERVER["HTTP_HOST"], // your domain
        $secure,               // Use true over HTTPS
        $httpOnly              // Set true for $AUTH_COOKIE_NAME
    );
}

问题是在生成文件时有一个“等待”指示器，然后在文件下载后恢复正常。我喜欢这样做的方式是使用一个隐藏的iFrame和钩子帧的onload事件，让我的页面知道什么时候开始下载。

但是onload不会在Internet Explorer中触发文件下载(就像使用附件头令牌一样)。轮询服务器是可行的，但我不喜欢这种额外的复杂性。这就是我所做的:

目标隐藏iFrame像往常一样。 生成内容。用 2分钟内绝对超时。 发送JavaScript重定向回 调用客户端，本质上调用 第二次生成页面。注意:这将导致在Internet Explorer中触发onload事件，因为它就像一个普通页面一样。 从缓存中删除内容并 发送给客户端。

免责声明:不要在繁忙的站点上这样做，因为缓存会增加。但实际上，如果您的站点非常繁忙，那么长时间运行的进程无论如何都会耗尽您的线程。

下面是隐藏代码的样子，这是您真正需要的。

public partial class Download : System.Web.UI.Page
{
    protected System.Web.UI.HtmlControls.HtmlControl Body;

    protected void Page_Load( object sender, EventArgs e )
    {
        byte[ ] data;
        string reportKey = Session.SessionID + "_Report";

        // Check is this page request to generate the content
        //    or return the content (data query string defined)
        if ( Request.QueryString[ "data" ] != null )
        {
            // Get the data and remove the cache
            data = Cache[ reportKey ] as byte[ ];
            Cache.Remove( reportKey );

            if ( data == null )
                // send the user some information
                Response.Write( "Javascript to tell user there was a problem." );
            else
            {
                Response.CacheControl = "no-cache";
                Response.AppendHeader( "Pragma", "no-cache" );
                Response.Buffer = true;

                Response.AppendHeader( "content-disposition", "attachment; filename=Report.pdf" );
                Response.AppendHeader( "content-size", data.Length.ToString( ) );
                Response.BinaryWrite( data );
            }
            Response.End();
        }
        else
        {
            // Generate the data here. I am loading a file just for an example
            using ( System.IO.FileStream stream = new System.IO.FileStream( @"C:\1.pdf", System.IO.FileMode.Open ) )
                using ( System.IO.BinaryReader reader = new System.IO.BinaryReader( stream ) )
                {
                    data = new byte[ reader.BaseStream.Length ];
                    reader.Read( data, 0, data.Length );
                }

            // Store the content for retrieval
            Cache.Insert( reportKey, data, null, DateTime.Now.AddMinutes( 5 ), TimeSpan.Zero );

            // This is the key bit that tells the frame to reload this page
            //   and start downloading the content. NOTE: Url has a query string
            //   value, so that the content isn't generated again.
            Body.Attributes.Add("onload", "window.location = 'binary.aspx?data=t'");
        }
    }

一个非常简单(蹩脚)的一行解决方案是使用window.onblur()事件关闭加载对话框。当然，如果它花了太长时间，用户决定做其他事情(如阅读电子邮件)，加载对话框将关闭。

来自其他地方的有效解决方案:

/**
 *  download file, show modal
 *
 * @param uri link
 * @param name file name
 */
function downloadURI(uri, name) {
// <------------------------------------------       Do something (show loading)
    fetch(uri)
        .then(resp => resp.blob())
        .then(blob => {
            const url = window.URL.createObjectURL(blob);
            const a = document.createElement('a');
            a.style.display = 'none';
            a.href = url;
            // the filename you want
            a.download = name;
            document.body.appendChild(a);
            a.click();
            window.URL.revokeObjectURL(url);
            // <----------------------------------------  Detect here (hide loading)
            alert('File detected');
        })
        .catch(() => alert('An error sorry'));
}

你可以使用它:

downloadURI("www.linkToFile.com", "file.name");

我在这个配置中遇到了同样的问题:

Struts 1.2.9 jQuery 1.3.2。 jQuery UI 1.7.1.custom Internet Explorer 11 Java 5

我用饼干的解决方案:

客户端:

在提交表单时，调用JavaScript函数隐藏页面并加载等待的旋转器

function loadWaitingSpinner() {
    ... hide your page and show your spinner ...
}

然后，调用一个函数，每500毫秒检查一次cookie是否来自服务器。

function checkCookie() {
    var verif = setInterval(isWaitingCookie, 500, verif);
}

如果找到cookie，停止每500毫秒检查一次，使cookie过期并调用函数返回页面并删除等待spinner (removeWaitingSpinner())。如果您希望能够再次下载另一个文件，过期cookie是很重要的!

function isWaitingCookie(verif) {
    var loadState = getCookie("waitingCookie");
    if (loadState == "done") {
        clearInterval(verif);
        document.cookie = "attenteCookie=done; expires=Tue, 31 Dec 1985 21:00:00 UTC;";
        removeWaitingSpinner();
    }
}

function getCookie(cookieName) {
    var name = cookieName + "=";
    var cookies = document.cookie
    var cs = cookies.split(';');
    for (var i = 0; i < cs.length; i++) {
        var c = cs[i];
        while(c.charAt(0) == ' ') {
            c = c.substring(1);
        }
        if (c.indexOf(name) == 0) {
            return c.substring(name.length, c.length);
        }
    }
    return "";
}

function removeWaitingSpinner() {
    ... come back to your page and remove your spinner ...
}

服务器端:

在服务器进程结束时，向响应添加一个cookie。当您的文件准备好下载时，cookie将被发送到客户端。

Cookie waitCookie = new Cookie("waitingCookie", "done");
response.addCookie(waitCookie);

这个Java/Spring示例检测下载的结束，在这一点上它隐藏了“Loading…”指示符。

方法:在JavaScript方面，设置一个最大过期时间为2分钟的cookie，并每秒钟轮询一次cookie过期时间。然后服务器端用更早的过期时间覆盖这个cookie——服务器进程的完成。一旦在JavaScript轮询中检测到cookie过期，“Loading…”就会被隐藏。

JavaScript的一面

function buttonClick() { // Suppose this is the handler for the button that starts
    $("#loadingProgressOverlay").show();  // Show loading animation
    startDownloadChecker("loadingProgressOverlay", 120);
    // Here you launch the download URL...
    window.location.href = "myapp.com/myapp/download";
}

// This JavaScript function detects the end of a download.
// It does timed polling for a non-expired Cookie, initially set on the
// client-side with a default max age of 2 min.,
// but then overridden on the server-side with an *earlier* expiration age
// (the completion of the server operation) and sent in the response.
// Either the JavaScript timer detects the expired cookie earlier than 2 min.
// (coming from the server), or the initial JavaScript-created cookie expires after 2 min.
function startDownloadChecker(imageId, timeout) {

    var cookieName = "ServerProcessCompleteChecker";  // Name of the cookie which is set and later overridden on the server
    var downloadTimer = 0;  // Reference to the timer object

    // The cookie is initially set on the client-side with a specified default timeout age (2 min. in our application)
    // It will be overridden on the server side with a new (earlier) expiration age (the completion of the server operation),
    // or auto-expire after 2 min.
    setCookie(cookieName, 0, timeout);

    // Set a timer to check for the cookie every second
    downloadTimer = window.setInterval(function () {

        var cookie = getCookie(cookieName);

        // If cookie expired (NOTE: this is equivalent to cookie "doesn't exist"), then clear "Loading..." and stop polling
        if ((typeof cookie === 'undefined')) {
            $("#" + imageId).hide();
            window.clearInterval(downloadTimer);
        }

    }, 1000); // Every second
}

// These are helper JavaScript functions for setting and retrieving a Cookie
function setCookie(name, value, expiresInSeconds) {
    var exdate = new Date();
    exdate.setTime(exdate.getTime() + expiresInSeconds * 1000);
    var c_value = escape(value) + ((expiresInSeconds == null) ? "" : "; expires=" + exdate.toUTCString());
    document.cookie = name + "=" + c_value + '; path=/';
}

function getCookie(name) {
    var parts = document.cookie.split(name + "=");
    if (parts.length == 2 ) {
        return parts.pop().split(";").shift();
    }
}

Java/Spring服务器端

    @RequestMapping("/download")
    public String download(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //... Some logic for downloading, returning a result ...

        // Create a Cookie that will override the JavaScript-created
        // Max-Age-2min Cookie with an earlier expiration (same name)
        Cookie myCookie = new Cookie("ServerProcessCompleteChecker", "-1");
        myCookie.setMaxAge(0); // This is immediate expiration, but can also
                               // add +3 seconds for any flushing concerns
        myCookie.setPath("/");
        response.addCookie(myCookie);
        //... -- presumably the download is writing to the Output Stream...
        return null;
}