尝试从 azure blob 下载文件，mime 类型问题

Question

我有以下代码在按下按钮时通过 ajax 调用下载文件。奇怪的是它实际上工作正常，给了我预期的文件，一段时间，当我重新访问以更改一些命名约定时，mime 类型给我带来了问题。下载时，它告诉我资源被解释为 Document 但与 application/octet-stream 一起传输。这些文件可以是 pdf、图像或 word 文档，我想一种方法是检查扩展名并分配正确的 mime 类型，但有没有更通用的方法，或者我可以从字节流不知何故？

try    {
    // Get blob.
    $blob = $blobClient->getBlob($container, $blob_name);
    $properties = $blobClient->getBlobProperties($container, $blob_name);
    $size = $properties->getProperties()->getContentLength();
    $mime = $properties->getProperties()->getContentType();

    header("Content-type: $mime");
    header("Content-length: $size");
    header ("Content-Disposition: attachment; filename=$blob_name");
    fpassthru($blob->getContentStream());

}

Answer 1

您可以使用finfo() 函数来获取要下载的文件的mime-type。

这里是示例代码sn-p。

<?php

try {
    // Get blob.
    $blob = $blobClient->getBlob($container, $blob_name);
    $properties = $blobClient->getBlobProperties($container, $blob_name);
    $size = $properties->getProperties()->getContentLength();

    $content = stream_get_contents($blob->getContentStream());  
    $finfo = new finfo(FILEINFO_MIME);
    $mime = $finfo->buffer($content);

    header("Content-type: $mime");
    header("Content-length: $size");
    header ("Content-Disposition: inline; filename=$blob_name");

    print_r($content);

} catch(ServiceException $e) {

    $code = $e->getCode();
    $error_message = $e->getMessage();
    echo $code.": ".$error_message."<br />";
}

但是，您也可以根据文件扩展名检索文件的 MIME 类型。而且它比finfo() 函数更有效，尤其是当你有大文件要下载时。因为stream_get_contents会先把整个文件加载到内存中。

以下是从文件扩展名中获取 mime-type 的示例：

<?php

try {
    // Get blob.
    $blob = $blobClient->getBlob($container, $blob_name);
    $properties = $blobClient->getBlobProperties($container, $blob_name);
    $size = $properties->getProperties()->getContentLength();

    $value = explode('.', $blob_name);
    $extension = strtolower(end($value));
    $mime = detectByFileExtension($extension);

    header("Content-type: $mime");
    header("Content-length: $size");
    header ("Content-Disposition: inline; filename=$blob_name");

    fpassthru($blob->getContentStream());

} catch(ServiceException $e) {

    $code = $e->getCode();
    $error_message = $e->getMessage();
    echo $code.": ".$error_message."<br />";
}

function detectByFileExtension($extension) {    
    $extensionToMimeTypeMap = getExtensionToMimeTypeMap();

    if (isset($extensionToMimeTypeMap[$extension])) {
        return $extensionToMimeTypeMap[$extension];
    }
    return 'text/plain';
}

function getExtensionToMimeTypeMap() {
    return [
        'hqx'   => 'application/mac-binhex40',
        'cpt'   => 'application/mac-compactpro',
        'csv'   => 'text/x-comma-separated-values',
        'bin'   => 'application/octet-stream',
        'dms'   => 'application/octet-stream',
        'lha'   => 'application/octet-stream',
        'lzh'   => 'application/octet-stream',
        'exe'   => 'application/octet-stream',
        'class' => 'application/octet-stream',
        'psd'   => 'application/x-photoshop',
        'so'    => 'application/octet-stream',
        'sea'   => 'application/octet-stream',
        'dll'   => 'application/octet-stream',
        'oda'   => 'application/oda',
        'pdf'   => 'application/pdf',
        'ai'    => 'application/pdf',
        'eps'   => 'application/postscript',
        'ps'    => 'application/postscript',
        'smi'   => 'application/smil',
        'smil'  => 'application/smil',
        'mif'   => 'application/vnd.mif',
        'xls'   => 'application/vnd.ms-excel',
        'ppt'   => 'application/powerpoint',
        'pptx'  => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
        'wbxml' => 'application/wbxml',
        'wmlc'  => 'application/wmlc',
        'dcr'   => 'application/x-director',
        'dir'   => 'application/x-director',
        'dxr'   => 'application/x-director',
        'dvi'   => 'application/x-dvi',
        'gtar'  => 'application/x-gtar',
        'gz'    => 'application/x-gzip',
        'gzip'  => 'application/x-gzip',
        'php'   => 'application/x-httpd-php',
        'php4'  => 'application/x-httpd-php',
        'php3'  => 'application/x-httpd-php',
        'phtml' => 'application/x-httpd-php',
        'phps'  => 'application/x-httpd-php-source',
        'js'    => 'application/javascript',
        'swf'   => 'application/x-shockwave-flash',
        'sit'   => 'application/x-stuffit',
        'tar'   => 'application/x-tar',
        'tgz'   => 'application/x-tar',
        'z'     => 'application/x-compress',
        'xhtml' => 'application/xhtml+xml',
        'xht'   => 'application/xhtml+xml',
        'zip'   => 'application/x-zip',
        'rar'   => 'application/x-rar',
        'mid'   => 'audio/midi',
        'midi'  => 'audio/midi',
        'mpga'  => 'audio/mpeg',
        'mp2'   => 'audio/mpeg',
        'mp3'   => 'audio/mpeg',
        'aif'   => 'audio/x-aiff',
        'aiff'  => 'audio/x-aiff',
        'aifc'  => 'audio/x-aiff',
        'ram'   => 'audio/x-pn-realaudio',
        'rm'    => 'audio/x-pn-realaudio',
        'rpm'   => 'audio/x-pn-realaudio-plugin',
        'ra'    => 'audio/x-realaudio',
        'rv'    => 'video/vnd.rn-realvideo',
        'wav'   => 'audio/x-wav',
        'jpg'   => 'image/jpeg',
        'jpeg'  => 'image/jpeg',
        'jpe'   => 'image/jpeg',
        'png'   => 'image/png',
        'gif'   => 'image/gif',
        'bmp'   => 'image/bmp',
        'tiff'  => 'image/tiff',
        'tif'   => 'image/tiff',
        'svg'   => 'image/svg+xml',
        'css'   => 'text/css',
        'html'  => 'text/html',
        'htm'   => 'text/html',
        'shtml' => 'text/html',
        'txt'   => 'text/plain',
        'text'  => 'text/plain',
        'log'   => 'text/plain',
        'rtx'   => 'text/richtext',
        'rtf'   => 'text/rtf',
        'xml'   => 'application/xml',
        'xsl'   => 'application/xml',
        'mpeg'  => 'video/mpeg',
        'mpg'   => 'video/mpeg',
        'mpe'   => 'video/mpeg',
        'qt'    => 'video/quicktime',
        'mov'   => 'video/quicktime',
        'avi'   => 'video/x-msvideo',
        'movie' => 'video/x-sgi-movie',
        'doc'   => 'application/msword',
        'docx'  => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'dot'   => 'application/msword',
        'dotx'  => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'xlsx'  => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        'word'  => 'application/msword',
        'xl'    => 'application/excel',
        'eml'   => 'message/rfc822',
        'json'  => 'application/json',
        'pem'   => 'application/x-x509-user-cert',
        'p10'   => 'application/x-pkcs10',
        'p12'   => 'application/x-pkcs12',
        'p7a'   => 'application/x-pkcs7-signature',
        'p7c'   => 'application/pkcs7-mime',
        'p7m'   => 'application/pkcs7-mime',
        'p7r'   => 'application/x-pkcs7-certreqresp',
        'p7s'   => 'application/pkcs7-signature',
        'crt'   => 'application/x-x509-ca-cert',
        'crl'   => 'application/pkix-crl',
        'der'   => 'application/x-x509-ca-cert',
        'kdb'   => 'application/octet-stream',
        'pgp'   => 'application/pgp',
        'gpg'   => 'application/gpg-keys',
        'sst'   => 'application/octet-stream',
        'csr'   => 'application/octet-stream',
        'rsa'   => 'application/x-pkcs7',
        'cer'   => 'application/pkix-cert',
        '3g2'   => 'video/3gpp2',
        '3gp'   => 'video/3gp',
        'mp4'   => 'video/mp4',
        'm4a'   => 'audio/x-m4a',
        'f4v'   => 'video/mp4',
        'webm'  => 'video/webm',
        'aac'   => 'audio/x-acc',
        'm4u'   => 'application/vnd.mpegurl',
        'm3u'   => 'text/plain',
        'xspf'  => 'application/xspf+xml',
        'vlc'   => 'application/videolan',
        'wmv'   => 'video/x-ms-wmv',
        'au'    => 'audio/x-au',
        'ac3'   => 'audio/ac3',
        'flac'  => 'audio/x-flac',
        'ogg'   => 'audio/ogg',
        'kmz'   => 'application/vnd.google-earth.kmz',
        'kml'   => 'application/vnd.google-earth.kml+xml',
        'ics'   => 'text/calendar',
        'zsh'   => 'text/x-scriptzsh',
        '7zip'  => 'application/x-7z-compressed',
        'cdr'   => 'application/cdr',
        'wma'   => 'audio/x-ms-wma',
        'jar'   => 'application/java-archive',
    ];
}

此外，将文件上传到 Azure 存储的最佳做法始终是为 blob 设置 Content-type，然后您可以使用上面提供的代码从 Azure 存储下载具有正确 mime 类型的文件。

下面的代码示例展示了如何将 blob 上传到具有 Content-type 的容器中：

<?php

require_once 'vendor/autoload.php';

use WindowsAzure\Common\ServicesBuilder;
use MicrosoftAzure\Storage\Blob\Models\CreateBlobOptions;

$connectionString = "DefaultEndpointsProtocol=https;AccountName=$account;AccountKey=$key";

$blobClient = ServicesBuilder::getInstance()->createBlobService($connectionString);

$filetoUpload = realpath('./image.jpg');
$content = fopen($filetoUpload, "r");
$mime = mime_content_type($filetoUpload);
$blob_name = "image.jpg";

try {
    //Upload blob
    $options = new CreateBlobOptions();
    $options->setContentType($mime);
    $blobClient->createBlockBlob("mycontainer", $blob_name, $content, $options);
}
catch(ServiceException $e) {
    $code = $e->getCode();
    $error_message = $e->getMessage();
    echo $code.": ".$error_message."<br />";
}