检查URL是否返回PDF

Question

我需要检查URL是否返回使用PHP的PDF文档。现在我使用的是file_get_mimetype函数。普通URL(https://www.google.com/)返回类型为应用程序/八位字节流，而普通pdf链接(http://www.brainlens.org/content/newsletters/Spring%202013.pdf)返回应用程序/pdf。但现在我也遇到了像http://www.dadsgarage.com/~/media/Files/example.ashx或http://www.wpdn.org/webfm_send/241这样的网址，它们也是pdf格式，但返回的是应用程序/八位字节流。还有其他的URL，它打开一个另存为对话框，这也必须被检测。

Answer 1

使用get_headers()

例如：

$url = "http://www.dadsgarage.com/~/media/Files/example.ashx";
if (in_array("Content-Type: application/pdf", get_headers($url))) {
    echo "URL returns PDF";
}

print_r(get_headers($url));

返回

Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Cache-Control: private, max-age=604800
    [2] => Content-Length: 194007
    [3] => Content-Type: application/pdf
    [4] => Expires: Tue, 09 Dec 2014 09:40:20 GMT
    [5] => Last-Modified: Wed, 07 Aug 2013 16:46:30 GMT
    [6] => Accept-Ranges: bytes
    [7] => Server: Microsoft-IIS/8.0
    [8] => Content-Disposition: inline; filename="example.pdf"
    [9] => X-AspNet-Version: 4.0.30319
    [10] => X-Powered-By: ASP.NET
    [11] => X-Provider: AWS
    [12] => Date: Tue, 02 Dec 2014 09:40:20 GMT
    [13] => Connection: close
)

Answer 2

mime类型可能包括：

application/pdf, application/x-pdf, application/acrobat, applications/vnd.pdf, text/pdf, text/x-pdf