如何从 PPT 或 docx 的 Base 64 字符串获取 MIME-TYPE？

Question

我从追加中获取 Base64 字符串，然后用 PHP 对其进行解码并将其保存在数据库中。

该字符串可以是任何文件 .pdf、.img、.docx、.zip、.ppt、.docx 等。

我的 base64 字符串不包含 mime 类型，例如“data:application/pdf;base64”部分。所以我需要获取 base64 的 mime 类型。

有什么办法可以用PHP解决这个问题吗？

目前，我正在使用此代码，它对于图像和 pdf 工作得很好。

$file = base64_decode($formData['image'], true)

$mineType = $this->getMimeType($file);

public function getBytesFromHexString($hexdata)

{

    for ($count = 0; $count < strlen($hexdata); $count += 2)

        $bytes[] = chr(hexdec(substr($hexdata, $count, 2)));

    return implode($bytes);

}

public function getMimeType($imagedata)

{

    $imagemimetypes = array(

        "jpg" => "FFD8",

        "png" => "89504E470D0A1A0A",

        "gif" => "474946",

        "bmp" => "424D",

        "tiff" => "4949",

        "pdf" => "25504446",

        "docx"=> "504B0304",

        "doc" => "D0CF11E0A1",

        "xlsx"=> "504B030414000600",

        "xls" => "D0CF11E0A1B11AE1"

    );

    foreach ($imagemimetypes as $mime => $hexbytes) {

        $bytes = $this->getBytesFromHexString($hexbytes);

        if (substr($imagedata, 0, strlen($bytes)) == $bytes){

            return $mime;

        }

    }

    return false;

}

Answer 1

function base64_mimetype(string $encoded, bool $strict = true): ?string {&nbsp; &nbsp; if ($decoded = base64_decode($encoded, $strict)) {&nbsp; &nbsp; &nbsp; &nbsp; $tmpFile = tmpFile();&nbsp; &nbsp; &nbsp; &nbsp; $tmpFilename = stream_get_meta_data($tmpFile)['uri'];&nbsp; &nbsp; &nbsp; &nbsp; file_put_contents($tmpFilename, $decoded);&nbsp; &nbsp; &nbsp; &nbsp; return mime_content_type($tmpFilename) ?: null;&nbsp; &nbsp; }&nbsp; &nbsp; return null;}http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types