如何从javascript高效访问gzip压缩包？ [英] How do I efficiently access gzipped xml from javascript?

问题描述

我需要从javascript（实际上来自Greasemonkey）有效地访问一个大型的gzip压缩文件。
不幸的是，服务器没有提供Content-Encoding标头，而Content-Type是application / x-gzip，所以firefox不会（据我所知）自动对它进行充气。
如果有办法伪造firefox，这将是理想的。除此之外，我需要一些方法来有效地进行通货膨胀...我现在使用的东西大约需要30秒才能收缩1.2Mb的压缩文件;我希望在5秒内完成它。

I need to efficently access a large gzipped xml file from javascript (actually from Greasemonkey). Unfortunately, the server doesn't provide a Content-Encoding header, and Content-Type is "application/x-gzip", so firefox will not (as far as I can tell) automatically inflate it. If there's a way to fake firefox out, that would be ideal. Short of that, I need some way to efficiently do the inflation...what I'm using now takes about 30 seconds to deflate the 1.2Mb gzipped file; I'd like to get it down under 5 seconds.

（我正在研究的Greasemonkey脚本不能有任何其他外部服务器依赖，所以代理和呈现Content-Encoding标头不是一个选项。）

(The Greasemonkey script I'm working on can't have any other external server dependencies, so proxying and presenting a Content-Encoding header isn't an option.)

我现在在做什么，我从几个地方拼凑而成。要不受干扰地接收二进制数据，我正在使用 firefox XMLHTTPRequest overrideMimeType 扩展名：

What I'm doing now, I've patched together from several places. To receive the binary data unmolested, I'm using the firefox XMLHTTPRequest overrideMimeType extension:

$.ajax(url, {
    dataType:'text',
    beforeSend:function(xhr){
        xhr.overrideMimeType('text/plain; charset=x-user-defined')
    },
    success:function(data){
        var blob='';
        for (i=0; i<data.length; ++i)
            blob += String.fromCharCode(data.charCodeAt(i) & 0xff);
        ...

然后使用 https://github.com/dankogai/js-deflate/blob/master/rawinflate.js （有几个其他javascript在那里扩充库，据我所知，基于一个较旧的库 http://www.onicos.com/staff/iz/amuse/javascript/expert/inflate.txt ）。这是一个非常缓慢的部分。

Then inflating, using a slightly modified and inlined copy of https://github.com/dankogai/js-deflate/blob/master/rawinflate.js (there are several other javascript inflate libraries out there, all as far as I can tell based on an older library http://www.onicos.com/staff/iz/amuse/javascript/expert/inflate.txt). This is the horrifically slow part.

        // blithely assuming the gzip header won't change,
        // strip a fixed number of bytes from the front
        deflated=RawDeflate.inflate(blob.substring(22,blob.length-8));

然后在innerHTML属性中弹出它来解析它：

Then popping it in an innerHTML property to parse it:

        xmlcontainer=$('<div>');
        // remove <?xml...> prolog
        xmlcontainer.html(deflated.substring(45));
        xmldoc=xmldoc.children();

（我知道使用DOMParser的parseFromString可以更好地完成最后一点，但我没有得到那个工作了。）

(I know the last bit could be more properly done with DOMParser's parseFromString, but I didn't get that working yet.)

推荐答案

你只是不能用这种配置做得更好**。

You're just not going to be able to do noticeably better with this configuration**.

JavaScript太慢而无法按预期快速膨胀，并且您无法从JS可靠地调用二进制文件 - 除非将数据AJAX化到您自己的服务器（可以是本地PC）。

JavaScript is too slow to inflate as fast as desired, and you can't call a binary reliably from JS -- unless AJAXing the data to your own server (which can be the local PC).

您的改进选择似乎是：

1. 让浏览器自动对内容进行充气。如果您已尝试使用 overrideMimeType 设置 application / x-gzip ，则可以尝试使用 GM_xmlhttpRequest （这是一个很长的镜头）。

1. Get the browser to automatically inflate the content. If you have already tried using overrideMimeType to set application/x-gzip, you might try using GM_xmlhttpRequest instead (it's a long shot).

转换这从GM脚本到Firefox附加组件。作为附加组件，您可以访问二进制文件，例如 7-Zip ，甚至可以访问浏览器的inflate方法。你也许可以更容易地欺骗mimetype。

Convert this from a GM script to a Firefox add-on. As an add-on, you can access binaries, like 7-Zip, and might even have access to the browser's inflate method. You could probably spoof the mimetype more easily too.

**我确实注意到一些琐碎的机会来加速JS的膨胀...像 length 这样的检查在内循环。唉，考虑到细节，可能不会购买超过一两秒。

**I did notice some trivial opportunities to speed up that inflating JS... things like length checks inside for loops. Alas, given the particulars, probably not going to buy more than a second or two.

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