创建一个表单，使用POST方法，提交表单-不需要iframe。当服务器页面响应请求时，为文件的mime类型写一个响应头，它将呈现一个下载对话框——我已经做过很多次了。

你想要内容类型的应用程序/下载-只要搜索如何为你使用的任何语言提供下载。

还有另一种解决方案下载ajax网页。但我指的是必须首先处理然后下载的页面。

首先，您需要将页面处理与结果下载分离。

1) ajax调用中只进行页面计算。

$.post("CalculusPage.php", { calculusFunction: true, ID: 29, data1: "a", data2: "b" },

       function(data, status) 
       {
            if (status == "success") 
            {
                /* 2) In the answer the page that uses the previous calculations is downloaded. For example, this can be a page that prints the results of a table calculated in the ajax call. */
                window.location.href = DownloadPage.php+"?ID="+29;
            }               
       }
);

// For example: in the CalculusPage.php

    if ( !empty($_POST["calculusFunction"]) ) 
    {
        $ID = $_POST["ID"];

        $query = "INSERT INTO ExamplePage (data1, data2) VALUES ('".$_POST["data1"]."', '".$_POST["data2"]."') WHERE id = ".$ID;
        ...
    }

// For example: in the DownloadPage.php

    $ID = $_GET["ID"];

    $sede = "SELECT * FROM ExamplePage WHERE id = ".$ID;
    ...

    $filename="Export_Data.xls";
    header("Content-Type: application/vnd.ms-excel");
    header("Content-Disposition: inline; filename=$filename");

    ...

我希望这个解决方案对很多人都有用，就像对我一样。

下面是我使用临时隐藏表单的解决方案。

//Create an hidden form
var form = $('<form>', {'method': 'POST', 'action': this.href}).hide();

//Add params
var params = { ...your params... };
$.each(params, function (k, v) {
    form.append($('<input>', {'type': 'hidden', 'name': k, 'value': v}));
});

//Make it part of the document and submit
$('body').append(form);
form.submit();

//Clean up
form.remove();

注意，我大量使用JQuery，但你可以用原生JS做同样的事情。

我看到你已经找到了一个解决方案，但我只是想添加一些信息，这可能有助于有人试图实现与大POST请求相同的事情。

几周前我也遇到了同样的问题，确实不可能通过AJAX实现“干净”的下载，Filament Group创建了一个jQuery插件，它的工作方式与您已经发现的完全相同，它被称为jQuery文件下载，但这种技术有一个缺点。

If you're sending big requests through AJAX (say files +1MB) it will negatively impact responsiveness. In slow Internet connections you'll have to wait a lot until the request is sent and also wait for the file to download. It isn't like an instant "click" => "popup" => "download start". It's more like "click" => "wait until data is sent" => "wait for response" => "download start" which makes it appear the file double its size because you'll have to wait for the request to be sent through AJAX and get it back as a downloadable file.

如果您使用的是小于1MB的小文件，则不会注意到这一点。但正如我在自己的应用程序中发现的那样，对于更大的文件大小来说，这几乎是无法忍受的。

我的应用程序允许用户导出动态生成的图像，这些图像通过POST请求以base64格式发送到服务器(这是唯一可能的方式)，然后处理并以.png， .jpg文件的形式发送回用户，图像的base64字符串+1MB是巨大的，这迫使用户等待超过必要的文件开始下载。在网速较慢的情况下，这真的很烦人。

我的解决方案是将文件临时写入服务器，一旦它准备好了，动态生成一个链接到文件的按钮形式，在“请等待…”和“下载”状态之间变化，同时，在预览弹出窗口中打印base64映像，以便用户可以“右键单击”并保存它。这使得所有的等待时间对用户来说更容易忍受，也加快了速度。

2014年9月30日更新:

自从我发布这篇文章以来，几个月过去了，最后我找到了一个更好的方法来加快使用大base64字符串的速度。我现在存储base64字符串到数据库(使用longtext或longblog字段)，然后我通过jQuery文件下载它的记录ID，最后在下载脚本文件上，我查询数据库使用这个ID拉base64字符串并通过下载函数传递它。

下载脚本示例:

<?php
// Record ID
$downloadID = (int)$_POST['id'];
// Query Data (this example uses CodeIgniter)
$data       = $CI->MyQueries->GetDownload( $downloadID );
// base64 tags are replaced by [removed], so we strip them out
$base64     = base64_decode( preg_replace('#\[removed\]#', '', $data[0]->image) );
// This example is for base64 images
$imgsize    = getimagesize( $base64 );
// Set content headers
header('Content-Disposition: attachment; filename="my-file.png"');
header('Content-type: '.$imgsize['mime']);
// Force download
echo $base64;
?>

我知道这远远超出了OP的要求，但是我觉得用我的发现更新我的答案会很好。当我在寻找我的问题的解决方案时，我读了很多“从AJAX POST数据下载”的帖子，这些帖子并没有给我我想要的答案，我希望这些信息能帮助那些想要实现这样的事情的人。

不要这么快就放弃，因为这可以(在现代浏览器中)使用FileAPI的部分:

var xhr = new XMLHttpRequest();
xhr.open('POST', url, true);
xhr.responseType = 'blob';
xhr.onload = function () {
    if (this.status === 200) {
        var blob = this.response;
        var filename = "";
        var disposition = xhr.getResponseHeader('Content-Disposition');
        if (disposition && disposition.indexOf('attachment') !== -1) {
            var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
            var matches = filenameRegex.exec(disposition);
            if (matches != null && matches[1]) filename = matches[1].replace(/['"]/g, '');
        }

        if (typeof window.navigator.msSaveBlob !== 'undefined') {
            // IE workaround for "HTML7007: One or more blob URLs were revoked by closing the blob for which they were created. These URLs will no longer resolve as the data backing the URL has been freed."
            window.navigator.msSaveBlob(blob, filename);
        } else {
            var URL = window.URL || window.webkitURL;
            var downloadUrl = URL.createObjectURL(blob);

            if (filename) {
                // use HTML5 a[download] attribute to specify filename
                var a = document.createElement("a");
                // safari doesn't support this yet
                if (typeof a.download === 'undefined') {
                    window.location.href = downloadUrl;
                } else {
                    a.href = downloadUrl;
                    a.download = filename;
                    document.body.appendChild(a);
                    a.click();
                }
            } else {
                window.location.href = downloadUrl;
            }

            setTimeout(function () { URL.revokeObjectURL(downloadUrl); }, 100); // cleanup
        }
    }
};
xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xhr.send($.param(params, true));

或者如果使用jQuery.ajax:

$.ajax({
    type: "POST",
    url: url,
    data: params,
    xhrFields: {
        responseType: 'blob' // to avoid binary data being mangled on charset conversion
    },
    success: function(blob, status, xhr) {
        // check for a filename
        var filename = "";
        var disposition = xhr.getResponseHeader('Content-Disposition');
        if (disposition && disposition.indexOf('attachment') !== -1) {
            var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
            var matches = filenameRegex.exec(disposition);
            if (matches != null && matches[1]) filename = matches[1].replace(/['"]/g, '');
        }

        if (typeof window.navigator.msSaveBlob !== 'undefined') {
            // IE workaround for "HTML7007: One or more blob URLs were revoked by closing the blob for which they were created. These URLs will no longer resolve as the data backing the URL has been freed."
            window.navigator.msSaveBlob(blob, filename);
        } else {
            var URL = window.URL || window.webkitURL;
            var downloadUrl = URL.createObjectURL(blob);

            if (filename) {
                // use HTML5 a[download] attribute to specify filename
                var a = document.createElement("a");
                // safari doesn't support this yet
                if (typeof a.download === 'undefined') {
                    window.location.href = downloadUrl;
                } else {
                    a.href = downloadUrl;
                    a.download = filename;
                    document.body.appendChild(a);
                    a.click();
                }
            } else {
                window.location.href = downloadUrl;
            }

            setTimeout(function () { URL.revokeObjectURL(downloadUrl); }, 100); // cleanup
        }
    }
});

我想指出在接受的答案中使用这种技术时出现的一些困难，即使用表单post:

You can't set headers on the request. If your authentication schema involves headers, a Json-Web-Token passed in the Authorization header, you'll have to find other way to send it, for example as a query parameter. You can't really tell when the request has finished. Well, you can use a cookie that gets set on response, as done by jquery.fileDownload, but it's FAR from perfect. It won't work for concurrent requests and it will break if a response never arrives. If the server responds with a error, the user will be redirected to the error page. You can only use the content types supported by a form. Which means you can't use JSON.

我最终使用在S3上保存文件并发送预签名URL来获取文件的方法。