处理文件下载从ajax张贴

我有一个javascript应用程序，发送ajax POST请求到某个URL。Response可以是JSON字符串，也可以是文件(作为附件)。我可以很容易地在ajax调用中检测到Content-Type和Content-Disposition，但是一旦我检测到响应包含一个文件，我如何让客户端下载它呢?我在这里读过一些类似的帖子，但没有一个能提供我想要的答案。

请，请，请不要发布建议我不应该使用ajax或我应该重定向浏览器的答案，因为这些都不是一个选项。使用普通的HTML表单也是不可行的。我所需要的是向客户端显示一个下载对话框。这能做到吗?如何做到?

当前回答

下面是我下载多个文件的解决方案，取决于一些由一些id组成的列表，并在数据库中查找，文件将被确定并准备下载-如果存在的话。我使用Ajax为每个文件调用c# MVC操作。

是的，就像其他人说的，它是可以在jQuery Ajax做到这一点。我用Ajax成功做到了，我总是发送响应200。

所以，这是关键:

  success: function (data, textStatus, xhr) {

这是我的代码:

var i = 0;
var max = 0;
function DownloadMultipleFiles() {
            if ($(".dataTables_scrollBody>tr.selected").length > 0) {
                var list = [];
                showPreloader();
                $(".dataTables_scrollBody>tr.selected").each(function (e) {
                    var element = $(this);
                    var orderid = element.data("orderid");
                    var iscustom = element.data("iscustom");
                    var orderlineid = element.data("orderlineid");
                    var folderPath = "";
                    var fileName = "";

                    list.push({ orderId: orderid, isCustomOrderLine: iscustom, orderLineId: orderlineid, folderPath: folderPath, fileName: fileName });
                });
                i = 0;
                max = list.length;
                DownloadFile(list);
            }
        }

然后调用:

function DownloadFile(list) {
        $.ajax({
            url: '@Url.Action("OpenFile","OrderLines")',
            type: "post",
            data: list[i],
            xhrFields: {
                responseType: 'blob'
            },
            beforeSend: function (xhr) {
                xhr.setRequestHeader("RequestVerificationToken",
                    $('input:hidden[name="__RequestVerificationToken"]').val());

            },
            success: function (data, textStatus, 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, '');
                    var a = document.createElement('a');
                    var url = window.URL.createObjectURL(data);
                    a.href = url;
                    a.download = filename;
                    document.body.append(a);
                    a.click();
                    a.remove();
                    window.URL.revokeObjectURL(url);
                }
                else {
                    getErrorToastMessage("Production file for order line " + list[i].orderLineId + " does not exist");
                }
                i = i + 1;
                if (i < max) {
                    DownloadFile(list);
                }
            },
            error: function (XMLHttpRequest, textStatus, errorThrown) {

            },
            complete: function () {
                if(i===max)
                hidePreloader();
            }
        });
    }

c# MVC:

 [HttpPost]
 [ValidateAntiForgeryToken]
public IActionResult OpenFile(OrderLineSimpleModel model)
        {
            byte[] file = null;

            try
            {
                if (model != null)
                {
                    //code for getting file from api - part is missing here as not important for this example
                    file = apiHandler.Get<byte[]>(downloadApiUrl, token);

                    var contentDispositionHeader = new System.Net.Mime.ContentDisposition
                    {
                        Inline = true,
                        FileName = fileName
                    };
                    //    Response.Headers.Add("Content-Disposition", contentDispositionHeader.ToString() + "; attachment");
                    Response.Headers.Add("Content-Type", "application/pdf");
                    Response.Headers.Add("Content-Disposition", "attachment; filename=" + fileName);
                    Response.Headers.Add("Content-Transfer-Encoding", "binary");
                    Response.Headers.Add("Content-Length", file.Length.ToString());

                }
            }
            catch (Exception ex)
            {
                this.logger.LogError(ex, "Error getting pdf", null);
                return Ok();
            }

            return File(file, System.Net.Mime.MediaTypeNames.Application.Pdf);
        }

只要你返回响应200，成功的Ajax可以与它一起工作，你可以检查文件是否实际存在，在这种情况下，下面的行将是假的，你可以通知用户:

 if (disposition && disposition.indexOf('attachment') !== -1) {

2020-04-01 14:07:17

其他回答

您使用的服务器端语言是什么?在我的应用程序中，我可以通过在PHP的响应中设置正确的标题轻松地从AJAX调用下载文件:

设置报头服务器端

header("HTTP/1.1 200 OK");
header("Pragma: public");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");

// The optional second 'replace' parameter indicates whether the header
// should replace a previous similar header, or add a second header of
// the same type. By default it will replace, but if you pass in FALSE
// as the second argument you can force multiple headers of the same type.
header("Cache-Control: private", false);

header("Content-type: " . $mimeType);

// $strFileName is, of course, the filename of the file being downloaded. 
// This won't have to be the same name as the actual file.
header("Content-Disposition: attachment; filename=\"{$strFileName}\""); 

header("Content-Transfer-Encoding: binary");
header("Content-Length: " . mb_strlen($strFile));

// $strFile is a binary representation of the file that is being downloaded.
echo $strFile;

这实际上会将浏览器“重定向”到这个下载页面，但正如@ahren已经在他的评论中说的，它不会导航离开当前页面。

这一切都是关于设置正确的头文件，所以我相信您会找到适合您所使用的服务器端语言(如果不是PHP的话)的解决方案。

处理响应客户端

假设您已经知道如何进行AJAX调用，那么在客户端向服务器执行AJAX请求。然后服务器生成一个可以下载该文件的链接，例如你想要指向的“转发”URL。例如，服务器响应如下:

{
    status: 1, // ok
    // unique one-time download token, not required of course
    message: 'http://yourwebsite.com/getdownload/ska08912dsa'
}

在处理响应时，你在你的主体中注入一个iframe，并将iframe的SRC设置为你刚刚接收到的URL，如下所示(使用jQuery来简化这个例子):

$("body").append("<iframe src='" + data.message +
  "' style='display: none;' ></iframe>");

如果您如上所示设置了正确的标题，iframe将强制下载对话框，而不需要将浏览器从当前页面导航出去。

Note

关于你的问题的额外补充;我认为使用AJAX技术请求东西时最好总是返回JSON。收到JSON响应后，就可以在客户端决定如何处理它。也许，例如，稍后您希望用户单击指向URL的下载链接，而不是强制直接下载，在您当前的设置中，您将不得不更新客户端和服务器端来实现这一点。

2013-04-18 15:00:45

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
        }
    }
});

2014-05-22 03:26:33

如果response是一个数组缓冲区，在Ajax的onsuccess事件下尝试这个:

 if (event.data instanceof ArrayBuffer) {
          var binary = '';
          var bytes = new Uint8Array(event.data);
          for (var i = 0; i < bytes.byteLength; i++) {
              binary += String.fromCharCode(bytes[i])
          }
          $("#some_id").append("<li><img src=\"data:image/png;base64," + window.btoa(binary) + "\"/></span></li>");
          return;
      }

事件的地方。数据是XHR事件成功函数接收到的响应。

2019-08-31 16:09:28

我是这么做的 https://stackoverflow.com/a/27563953/2845977

. ajax({美元 url: ' < URL_TO_FILE >”, 成功:函数(数据){ var blob=new blob ([data]); var链接= document.createElement (' a '); link.href = window.URL.createObjectURL (blob); link.download = " < FILENAME_TO_SAVE_WITH_EXTENSION >”; link.click (); ｝ })；

使用download.js更新答案

. ajax({美元 url: ' < URL_TO_FILE >”, 成功:下载。绑定(true， "<FILENAME_TO_SAVE_WITH_EXTENSION>"， "<FILE_MIME_TYPE>") })；

2017-08-30 19:06:06