检查网址指向一个文件或页面 [英] Check if url leads to a file or a page

问题描述

我们需要以下条件：

从URL下载一个文件，如果它实际上是一个文件。 。否则，如果它是一个网页无能为力

Download a file from an URL if it is actually a file. Otherwise if its a page do nothing.

有关一个简单的例子，我得到了下面的下载文件：

For a quick example I've got the following to download a file:

 My.Computer.Network.DownloadFile(
"http://www.wired.com/wiredenterprise/wp-content/uploads/2013/07/ff_googleinfrastructure_large.jpg",
"d:\ff_googleinfrastructure_large.jpg")

但是，如果我们得到了一个正常的网页，如 http://www.google.com 它只是下载这是我们不希望的页面。

But if we got a normal web page for example "http://www.google.com" it will just download the page which is something we do not want.

所以，我怎么能找出如果一个URL将导致一个文件，而不是网页？

So how can i find out if an URL will lead to a file instead of a page?

它可以是任何类型的文件，以便检查是否URL以.zip或.jpg或.DOCX或...根本不会做结束。

It could be any type of file so checking if the URL ends with .zip or .jpg or .docx or... simply won't do.

答案都欢迎这就是为什么我都标记

Answers in VB.NET or C# are both welcome which is why i marked both.

推荐答案

的时间提前，有没有100％准确的方法。你可以检查扩展（假如有），但即使不是100％万无一失。

Ahead of time, there's no 100% accurate way. You could check the extension (assuming there is one), but even that is not 100% foolproof.

您可以发出请求并检查内容类型页眉和救助下载如果值的文件为的text / html 或者一些文本 MIME变种。由于olydis低于所指出的，可以执行 HEAD 请求只得到响应头回来，如果你想下载完整的文件在这一点上再决定。

You could make the request and examine the content-type header and bail out of downloading the file if the value is text/html or some text MIME variant. As olydis points out below, you can perform a HEAD request to just get the response header back and decide then if you want to download the file in its entirety at that point.

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