Content-Disposition附件是否已从XMLHttpRequest中阻止？ [英] Is Content-Disposition attachment blocked from XMLHttpRequest?

问题描述

我想从我编写的C＃webserver执行png文件的javascript xhr请求。
这是我使用的代码

I want to perform a javascript xhr request for a png file from a C# webserver which I wrote. Here is the code I use

    var imgUrl = "http://localhost:8085/AnImage.png?" + now;
    var request = new XMLHttpRequest();
    request.open('GET', imgUrl, false);
    request.send(); // this is in a try/catch

在服务器端我发回文件并添加Content-Disposition标头。
我获得以下回复

On the server-side I send back the file and add a Content-Disposition header. I obtain the following response

我确保Content-Disposition在Content-Type之后附加在标题中（截图来自Firebug，后者附加）按字母顺序排列。）

I made sure that Content-Disposition was attached in the headers after the Content-Type (the screenshot is from Firebug, which appends in alphabetical order).

结果是没有触发对话框，我在回复中遗漏了什么？

The results is that no dialog box is triggered, am I missing something in the response?

编辑：
我想在javascript中执行所有操作有几个原因。
首先：我不想展示图像，我想把所有东西都放在幕后。
第二：在请求图像时，我希望仅在特定请求中添加Content-Disposition。此类请求标有警告标题，其值为AttachmentRequest

edit: I want to perform everything in javascript for several reasons. First: I don't want to show the image and I want to keep everything behind the curtain. Second: when requesting the image I want the Content-Disposition to be added only on particular requests. Such requests are marked with a "Warning" header with value "AttachmentRequest"

request.setRequestHeader("Warning","AttachmentRequest");

推荐答案

我不认为当请求是通过XHR时，Content-Disposition 会触发任何文件保存对话框。使用XHR表明你将在代码中处理结果。

I don't think Content-Disposition triggers any file save dialog when the request is via XHR. The use of XHR suggests you're going to handle the result in code.

如果你想要提示用户将图像保存到文件中，我就是成功使用了这种技术：

If you want the user to be prompted to save the image to a file, I've used this technique successfully:

window.open("http://localhost:8085/AnImage.png?" + now);

它的缺点是它会短暂地闪烁一个空白的打开窗口，直到标题到达，然后是新窗口关闭并出现保存文件对话框。

It has the downside that it flashes a blank open window briefly until the header arrives, then the new window closes and the "save file" dialog box appears.

使用 iframe 可能会阻止窗口闪烁：

Using an iframe may prevent the window flashing:

var f = document.createElement('iframe');
f.style.position = "absolute";
f.style.left = "-10000px";
f.src = "http://localhost:8085/AnImage.png?" + now;
document.body.appendChild(f);

另外，我想知道效果（如果有的话） Content-Disposition 处理 img 元素：

Separately, I wonder what effect (if any) Content-Disposition has on the handling of an img element:

var img = document.createElement('img');
img.style.position = "absolute";
img.style.left = "-10000px";
img.src = "http://localhost:8085/AnImage.png?" + now;
document.body.appendChild(img);

我没试过，但浏览器可能尊重标题。您需要确保在要支持的所有浏览器上进行测试。

I haven't tried that, but the browser might respect the header. You'd need to be sure to test on all of the browsers you want to support.

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