按扩展名的内容类型答案

【问题标题】：content type by extension按扩展名的内容类型
【发布时间】：2010-12-26 23:25:03
【问题描述】：

是否有根据文件扩展名返回内容类型的内置函数？

【问题讨论】：

扩展程序不会告诉您内容类型是什么。不要依赖它。
作为 Anon 评论的后续：扩展是完全瞬态的，因此可执行文件 (.exe) 可以轻松地重命名为您的应用程序期望的类型之一，而您的应用程序将无法确定重命名的文件实际上是其他类型。

【解决方案1】：

我不知道。但是你可以使用这个代码：

using Microsoft.Win32;

RegistryKey key = Registry.ClassesRoot.OpenSubKey(extension);
string contentType = key.GetValue("Content Type").ToString();

您需要添加额外的代码来处理错误。

注意：扩展名需要以点为前缀，如.txt。

【讨论】：

有没有办法去另一个方向？我有内容类型，我想用适当的扩展名缓存内容。
@Jordan：我建议你用这个创建一个问题。人们会在那里回答。
@cesargon 是否可以让浏览器下载名称和扩展名通过查询字符串传递的任何文件。请看我的问题，如果你能回答这个问题。 stackoverflow.com/questions/9927339

【解决方案2】：

FYKI，检查 \HKEY_CLASSES_ROOT\MIME\Database\Content Type 下的注册表。将有内容类型和文件扩展名的列表。如果您可以通过 Windows API 加载此信息，那么您可以获得文件扩展名到内容类型映射。

第

更新：[来源][1]

public string GetMIMEType(string filepath)
    {
        FileInfo fileInfo = new FileInfo(filepath);
        string fileExtension = fileInfo.Extension.ToLower();

        // direct mapping which is fast and ensures these extensions are found
        switch (fileExtension)
        {
            case "htm":
            case "html":
                return "text/html";
            case "js":
                return "text/javascript"; // registry may return "application/x-javascript"
        }



            // see if we can find extension info anywhere in the registry
    //Note : there is not a ContentType key under ALL the file types , check Run --> regedit , then extensions !!!

        RegistryPermission regPerm = new RegistryPermission(RegistryPermissionAccess.Read, @"\\HKEY_CLASSES_ROOT");

        // looks for extension with a content type
        RegistryKey rkContentTypes = Registry.ClassesRoot.OpenSubKey(fileExtension);
        if (rkContentTypes != null)
        {
            object key = rkContentTypes.GetValue("Content Type");
            if (key != null)
                return key.ToString().ToLower();
        }


        // looks for a content type with extension
        // Note : This would be problem if  multiple extensions associate with one content type.
        RegistryKey typeKey = Registry.ClassesRoot.OpenSubKey(@"MIME\Database\Content Type");

        foreach (string keyname in typeKey.GetSubKeyNames())
        {
            RegistryKey curKey = typeKey.OpenSubKey(keyname);
            if (curKey != null)
            {
                object extension = curKey.GetValue("Extension");
                if (extension != null)
                {
                    if (extension.ToString().ToLower() == fileExtension)
                    {
                        return keyname;
                    }
                }
            }
        }

        return null;
    }

[1]：http://www.codeproject.com/KB/dotnet/ContentType.aspx?msg=2903389#xx2903389xxenter code here

【讨论】：

我认为 mrblah 想从扩展中找到内容类型，而不是相反。查看 MIME 数据库 reg 密钥对于查找给定内容类型的文件扩展名很有用。
是的，你是对的，我认为，你的方法将查看 \HKEY_CLASSES_ROOT。它具有内容类型映射的扩展。使用我的方法，您可以获得值，但如果多个扩展与一种内容类型相关联，则会出现问题。
是否可以让浏览器下载任何名称和扩展名通过查询字符串传递的文件。请看我的问题，如果你能回答这个问题。 stackoverflow.com/questions/9927339

【解决方案3】：

这是我写的：

public string GetContentTypeByExtension(string strExtension)
{
    switch (strExtension)
    {
        case ".fif":

            return "application/fractals";
            break;

        case ".hta":

            return "application/hta";
            break;

        case ".hqx":

            return "application/mac-binhex40";
            break;

        case ".vsi":

            return "application/ms-vsi";
            break;

        case ".p10":

            return "application/pkcs10";
            break;

        case ".p7m":

            return "application/pkcs7-mime";
            break;

        case ".p7s":

            return "application/pkcs7-signature";
            break;

        case ".cer":

            return "application/pkix-cert";
            break;

        case ".crl":

            return "application/pkix-crl";
            break;

        case ".ps":

            return "application/postscript";
            break;

        case ".setpay":

            return "application/set-payment-initiation";
            break;

        case ".setreg":

            return "application/set-registration-initiation";
            break;

        case ".sst":

            return "application/vnd.ms-pki.certstore";
            break;

        case ".pko":

            return "application/vnd.ms-pki.pko";
            break;

        case ".cat":

            return "application/vnd.ms-pki.seccat";
            break;

        case ".stl":

            return "application/vnd.ms-pki.stl";
            break;

        case ".wpl":

            return "application/vnd.ms-wpl";
            break;

        case ".xps":

            return "application/vnd.ms-xpsdocument";
            break;

        case ".z":

            return "application/x-compress";
            break;

        case ".tgz":

            return "application/x-compressed";
            break;

        case ".gz":

            return "application/x-gzip";
            break;

        case ".ins":

            return "application/x-internet-signup";
            break;

        case ".iii":

            return "application/x-iphone";
            break;

        case ".jtx":

            return "application/x-jtx+xps";
            break;

        case ".latex":

            return "application/x-latex";
            break;

        case ".nix":

            return "application/x-mix-transfer";
            break;

        case ".asx":

            return "application/x-mplayer2";
            break;

        case ".application":

            return "application/x-ms-application";
            break;

        case ".wmd":

            return "application/x-ms-wmd";
            break;

        case ".wmz":

            return "application/x-ms-wmz";
            break;

        case ".xbap":

            return "application/x-ms-xbap";
            break;

        case ".p12":

            return "application/x-pkcs12";
            break;

        case ".p7b":

            return "application/x-pkcs7-certificates";
            break;

        case ".p7r":

            return "application/x-pkcs7-certreqresp";
            break;

        case ".sit":

            return "application/x-stuffit";
            break;

        case ".tar":

            return "application/x-tar";
            break;

        case ".man":

            return "application/x-troff-man";
            break;

        case ".cer":

            return "application/x-x509-ca-cert";
            break;

        case ".zip":

            return "application/x-zip-compressed";
            break;

        case ".xaml":

            return "application/xaml+xml";
            break;

        case ".xml":

            return "application/xml";
            break;

        case ".aiff":

            return "audio/aiff";
            break;

        case ".au":

            return "audio/basic";
            break;

        case ".mid":

            return "audio/mid";
            break;

        case ".mid":

            return "audio/midi";
            break;

        case ".mp3":

            return "audio/mp3";
            break;

        case ".mp3":

            return "audio/mpeg";
            break;

        case ".m3u":

            return "audio/mpegurl";
            break;

        case ".mp3":

            return "audio/mpg";
            break;

        case ".wav":

            return "audio/wav";
            break;

        case ".aiff":

            return "audio/x-aiff";
            break;

        case ".mid":

            return "audio/x-mid";
            break;

        case ".mid":

            return "audio/x-midi";
            break;

        case ".mp3":

            return "audio/x-mp3";
            break;

        case ".mp3":

            return "audio/x-mpeg";
            break;

        case ".m3u":

            return "audio/x-mpegurl";
            break;

        case ".mp3":

            return "audio/x-mpg";
            break;

        case ".wax":

            return "audio/x-ms-wax";
            break;

        case ".wma":

            return "audio/x-ms-wma";
            break;

        case ".wav":

            return "audio/x-wav";
            break;

        case ".bmp":

            return "image/bmp";
            break;

        case ".gif":

            return "image/gif";
            break;

        case ".jpg":

            return "image/jpeg";
            break;

        case ".jpg":

            return "image/pjpeg";
            break;

        case ".png":

            return "image/png";
            break;

        case ".tiff":

            return "image/tiff";
            break;

        case ".ico":

            return "image/x-icon";
            break;

        case ".png":

            return "image/x-png";
            break;

        case ".mid":

            return "midi/mid";
            break;

        case ".dwfx":

            return "model/vnd.dwfx+xps";
            break;

        case ".css":

            return "text/css";
            break;

        case ".323":

            return "text/h323";
            break;

        case ".htm":

            return "text/html";
            break;

        case ".uls":

            return "text/iuls";
            break;

        case ".txt":

            return "text/plain";
            break;

        case ".wsc":

            return "text/scriptlet";
            break;

        case ".htt":

            return "text/webviewhtml";
            break;

        case ".htc":

            return "text/x-component";
            break;

        case ".vcf":

            return "text/x-vcard";
            break;

        case ".xml":

            return "text/xml";
            break;

        case ".avi":

            return "video/avi";
            break;

        case ".mpeg":

            return "video/mpeg";
            break;

        case ".mpeg":

            return "video/mpg";
            break;

        case ".avi":

            return "video/msvideo";
            break;

        case ".mpeg":

            return "video/x-mpeg";
            break;

        case ".mpeg":

            return "video/x-mpeg2a";
            break;

        case ".asx":

            return "video/x-ms-asf";
            break;

        case ".asx":

            return "video/x-ms-asf-plugin";
            break;

        case ".wm":

            return "video/x-ms-wm";
            break;

        case ".wmv":

            return "video/x-ms-wmv";
            break;

        case ".wmx":

            return "video/x-ms-wmx";
            break;

        case ".wvx":

            return "video/x-ms-wvx";
            break;

        case ".avi":

            return "video/x-msvideo";
            break;


    }


}

【讨论】：

您有重复的案例陈述

【解决方案4】：

如果是上传的文件。您可以将内容类型存储在数据库的列中，以供您上传文件时使用。 HttpPostedFile 类有一个名为 ContentType 的属性。

【讨论】：

【解决方案5】：

从 .Net Framework 4.5 开始，有一个类 System.Web.MimeMapping，它具有完整的 mime 类型库以及获取请求的 mime 类型的方法。

见：http://msdn.microsoft.com/en-us/library/system.web.mimemapping(v=vs.110).aspx

或者对于GetMimeMapping的实现：https://referencesource.microsoft.com/#System.Web/MimeMapping.cs

【讨论】：

【解决方案6】：

要获得或多或少完整的列表，请查看下面的地图（C++，但可以直接将其更改为 C#）。

这就是 Google/Chrome 识别内容类型表单文件扩展的方式（不知道电子邮件正文是如何生成的 - 由客户端的 JavaScript 或服务器端的 POST - 我猜是后者）。我使用以下技巧得到了这个列表：

在 Internet 上搜索最常用的文件扩展名。很幸运能找到一个 html 表格，这样我就可以将它复制粘贴到 Excel 中，以获得一个包含扩展名的干净列表。
创建了一个包含几个字符的小文件test。
使用 (2) 中的扩展列表和一些命令行魔法来创建文件 test.TXT、test.HTM、test.TIFF 等等。 Linux 变体是for file in test.TXT test.HTM test.TIFF ... ; do cp test "$file"; done;
将所有这些文件作为附件发送到我的 gmail。请注意，出于安全原因，某些文件（如 .exe 和 .zip）已被过滤掉。 下面的代码中缺少它们！
在 gmail 中，下载原始文件，可以看到每个附加文件的 Content-Type: application/pdf; name="example.pdf" 行。在 VIM 中解析得到下面的列表。

如果您想添加不在下面列表中的扩展 - 创建小文件 sample.xyz，将其发送给自己并查看原始电子邮件中的 Content-Type。这就是诀窍。希望对您有所帮助！

附：我知道这不是最好的列表，但它足以让我学习如何以编程方式发送电子邮件附件并按文件扩展名选择 Content-Type，就像 gmail 一样。如果某些扩展类型“缺失”，请不要苛刻。

    static const map<string, string> ContentTypes = {
        { "TXT","text/plain" },
        { "HTM","text/html" },
        { "TIFF","image/tiff" },
        { "TMP","application/octet-stream" },
        { "TOAST","application/octet-stream" },
        { "TORRENT","application/x-bittorrent" },
        { "TTF","application/x-font-ttf" },
        { "UUE","application/octet-stream" },
        { "VCD","application/x-cdlink" },
        { "VCF","text/x-vcard" },
        { "VCXPROJ","application/xml" },
        { "VOB","application/octet-stream" },
        { "WAV","audio/x-wav" },
        { "WMA","audio/x-ms-wma" },
        { "WMV","video/x-ms-wmv" },
        { "WPD","application/wordperfect" },
        { "WPS","application/octet-stream" },
        { "XCODEPROJ","application/octet-stream" },
        { "XHTML","application/xhtml+xml" },
        { "XLR","application/octet-stream" },
        { "XLS","application/vnd.ms-excel" },
        { "XLSX","application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" },
        { "XML","text/xml" },
        { "YUV","application/octet-stream" },
        { "ZIPX","application/octet-stream" },
        { "3DM","application/octet-stream" },
        { "3DS","application/octet-stream" },
        { "3G2","video/3gpp2" },
        { "3GP","video/3gpp" },
        { "ACCDB","application/octet-stream" },
        { "AI","application/illustrator" },
        { "AIF","audio/x-aiff" },
        { "APK","application/vnd.android.package-archive" },
        { "APP","application/octet-stream" },
        { "ASF","video/x-ms-asf" },
        { "ASP","application/octet-stream" },
        { "ASPX","application/xml" },
        { "AVI","video/x-msvideo" },
        { "BAK","application/octet-stream" },
        { "BIN","application/octet-stream" },
        { "BMP","image/bmp" },
        { "C","text/x-csrc" },
        { "CAB","application/octet-stream" },
        { "CBR","application/octet-stream" },
        { "CER","application/x-x509-ca-cert" },
        { "CFG","application/octet-stream" },
        { "CFM","application/octet-stream" },
        { "CGI","application/octet-stream" },
        { "CLASS","application/octet-stream" },
        { "CPP","text/x-c++src" },
        { "CRDOWNLOAD","application/octet-stream" },
        { "CRX","application/x-chrome-extension" },
        { "CS","text/plain" },
        { "CSR","application/octet-stream" },
        { "CSS","text/css" },
        { "CSV","text/csv" },
        { "CUE","application/octet-stream" },
        { "CUR","application/octet-stream" },
        { "DAT","application/octet-stream" },
        { "DB","application/octet-stream" },
        { "DBF","application/octet-stream" },
        { "DDS","image/vnd.ms-dds" },
        { "DEB","application/x-debian-package" },
        { "DEM","application/octet-stream" },
        { "DESKTHEMEPACK","application/octet-stream" },
        { "DLL","application/octet-stream" },
        { "DMG","application/octet-stream" },
        { "DMP","application/octet-stream" },
        { "DOC","application/msword" },
        { "DOCX","application/vnd.openxmlformats-officedocument.wordprocessingml.document" },
        { "DRV","application/octet-stream" },
        { "DTD","application/xml-dtd" },
        { "DWG","application/octet-stream" },
        { "DXF","application/dxf" },
        { "EPS","application/postscript" },
        { "FLA","application/octet-stream" },
        { "FLV","video/x-flv" },
        { "FNT","application/octet-stream+fnt" },
        { "FON","application/octet-stream+fon" },
        { "GADGET","application/octet-stream" },
        { "GAM","application/octet-stream" },
        { "GED","application/octet-stream" },
        { "GIF","image/gif" },
        { "GPX","application/gpx+xml" },
        { "GZ","application/x-gzip" },
        { "H","text/x-chdr" },
        { "HQX","application/mac-binhex40" },
        { "HTML","text/html" },
        { "ICNS","application/octet-stream" },
        { "ICO","image/x-icon" },
        { "ICS","text/calendar" },
        { "IFF","application/octet-stream" },
        { "INDD","application/octet-stream" },
        { "INI","application/octet-stream" },
        { "ISO","application/octet-stream" },
        { "JAVA","application/octet-stream" },
        { "JPG","image/jpeg" },
        { "JSP","application/octet-stream" },
        { "KEY","application/octet-stream" },
        { "KEYCHAIN","application/octet-stream" },
        { "KML","application/vnd.google-earth.kml+xml" },
        { "KMZ","application/vnd.google-earth.kmz" },
        { "LOG","application/octet-stream" },
        { "LUA","application/octet-stream" },
        { "M","application/octet-stream" },
        { "M3U","audio/x-mpegurl" },
        { "M4A","audio/mp4" },
        { "M4V","video/x-m4v" },
        { "MAX","application/octet-stream" },
        { "MDB","application/octet-stream" },
        { "MDF","application/octet-stream" },
        { "MID","audio/midi" },
        { "MIM","application/octet-stream" },
        { "MOV","video/quicktime" },
        { "MP3","audio/mpeg" },
        { "MP4","video/mp4" },
        { "MPA","audio/mpeg" },
        { "MPG","video/mpeg" },
        { "MSG","application/octet-stream" },
        { "NES","application/octet-stream" },
        { "OBJ","application/octet-stream" },
        { "ODT","application/vnd.oasis.opendocument.text" },
        { "OTF","application/vnd.oasis.opendocument.formula-template" },
        { "PAGES","application/x-iwork-pages-sffpages" },
        { "PART","application/octet-stream" },
        { "PCT","application/octet-stream" },
        { "PDB","chemical/x-pdb" },
        { "PDF","application/pdf" },
        { "PHP","application/x-httpd-php" },
        { "PKG","application/octet-stream" },
        { "PL","application/octet-stream" },
        { "PLUGIN","application/octet-stream" },
        { "PNG","image/png" },
        { "PPS","application/vnd.ms-powerpoint" },
        { "PPT","application/vnd.ms-powerpoint" },
        { "PPTX","application/vnd.openxmlformats-officedocument.presentationml.presentation" },
        { "PRF","application/pics-rules" },
        { "PS","application/postscript" },
        { "PSD","application/photoshop" },
        { "PSPIMAGE","application/octet-stream" },
        { "PY","application/octet-stream" },
        { "RM","audio/x-pn-realaudio" },
        { "ROM","application/octet-stream" },
        { "RPM","application/x-rpm" },
        { "RSS","application/octet-stream" },
        { "RTF","application/rtf" },
        { "SAV","application/octet-stream" },
        { "SDF","application/octet-stream" },
        { "SH","application/x-sh" },
        { "SITX","application/octet-stream" },
        { "SLN","text/plain" },
        { "SQL","application/octet-stream" },
        { "SRT","application/octet-stream" },
        { "SVG","image/svg+xml" },
        { "SWF","application/x-shockwave-flash" },
        { "SWIFT","application/octet-stream" },
        { "TAX2016","application/octet-stream" },
        { "TEX","application/x-tex" }
    };

【讨论】：