Android mime type to file extension

MIME types (IANA media types)

A media type (also known as a Multipurpose Internet Mail Extensions or MIME type) indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF’s RFC 6838.

The Internet Assigned Numbers Authority (IANA) is responsible for all official MIME types, and you can find the most up-to-date and complete list at their Media Types page.

Warning: Browsers use the MIME type, not the file extension, to determine how to process a URL, so it’s important that web servers send the correct MIME type in the response’s Content-Type header. If this is not correctly configured, browsers are likely to misinterpret the contents of files, sites will not work correctly, and downloaded files may be mishandled.

Structure of a MIME type

A simplest MIME type consists of a type and a subtype. A MIME type comprises these strings concatenated with a slash ( / ). No whitespace is allowed in a MIME type:

The type represents the general category into which the data type falls, such as video or text .

The subtype identifies the exact kind of data of the specified type the MIME type represents. For example, for the MIME type text , the subtype might be plain (plain text), html (HTML source code), or calendar (for iCalendar/ .ics ) files.

Each type has its own set of possible subtypes. A MIME type always has both a type and a subtype, never just one or the other.

An optional parameter can be added to provide additional details:

For example, for any MIME type whose main type is text , you can add the optional charset parameter to specify the character set used for the characters in the data. If no charset is specified, the default is ASCII ( US-ASCII ) unless overridden by the user agent’s settings. To specify a UTF-8 text file, the MIME type text/plain;charset=UTF-8 is used.

MIME types are case-insensitive but are traditionally written in lowercase. The parameter values can be case-sensitive.

Types

There are two classes of type: discrete and multipart. Discrete types are types which represent a single file or medium, such as a single text or music file, or a single video. A multipart type is one which represents a document that’s comprised of multiple component parts, each of which may have its own individual MIME type; or, a multipart type may encapsulate multiple files being sent together in one transaction. For example, multipart MIME types are used when attaching multiple files to an email.

Discrete types

The discrete types currently registered with the IANA are:

Any kind of binary data that doesn’t fall explicitly into one of the other types; either data that will be executed or interpreted in some way or binary data that requires a specific application or category of application to use. Generic binary data (or binary data whose true type is unknown) is application/octet-stream . Other common examples include application/pdf , application/pkcs8 , and application/zip . (Registration at IANA)

Audio or music data. Examples include audio/mpeg , audio/vorbis . (Registration at IANA)

Reserved for use as a placeholder in examples showing how to use MIME types. These should never be used outside of sample code listings and documentation. example can also be used as a subtype; for instance, in an example related to working with audio on the web, the MIME type audio/example can be used to indicate that the type is a placeholder and should be replaced with an appropriate one when using the code in the real world.

Font/typeface data. Common examples include font/woff , font/ttf , and font/otf . (Registration at IANA)

Image or graphical data including both bitmap and vector still images as well as animated versions of still image formats such as animated GIF or APNG. Common examples are image/jpeg , image/png , and image/svg+xml . (Registration at IANA)

Model data for a 3D object or scene. Examples include model/3mf and model/vrml . (Registration at IANA)

Text-only data including any human-readable content, source code, or textual data such as comma-separated value (CSV) formatted data. Examples include: text/plain , text/csv , and text/html . (Registration at IANA)

Video data or files, such as MP4 movies ( video/mp4 ). (Registration at IANA)

For text documents without a specific subtype, text/plain should be used. Similarly, for binary documents without a specific or known subtype, application/octet-stream should be used.

Multipart types

Multipart types indicate a category of document broken into pieces, often with different MIME types; they can also be used — especially in email scenarios — to represent multiple, separate files which are all part of the same transaction. They represent a composite document.

With the exception of multipart/form-data , used in the POST method of HTML Forms, and multipart/byteranges , used with 206 Partial Content to send part of a document, HTTP doesn’t handle multipart documents in a special way: the message is transmitted to the browser (which will likely show a «Save As» window if it doesn’t know how to display the document).

There are two multipart types:

A message that encapsulates other messages. This can be used, for instance, to represent an email that includes a forwarded message as part of its data, or to allow sending very large messages in chunks as if it were multiple messages. Examples include message/rfc822 (for forwarded or replied-to message quoting) and message/partial to allow breaking a large message into smaller ones automatically to be reassembled by the recipient. (Registration at IANA)

Data that is comprised of multiple components which may individually have different MIME types. Examples include multipart/form-data (for data produced using the FormData API) and multipart/byteranges (defined in RFC 7233: 5.4.1 and used with HTTP’s 206 «Partial Content» response returned when the fetched data is only part of the content, such as is delivered using the Range header). (Registration at IANA)

Important MIME types for Web developers

application/octet-stream

This is the default for binary files. As it means unknown binary file, browsers usually don’t execute it, or even ask if it should be executed. They treat it as if the Content-Disposition header was set to attachment , and propose a «Save As» dialog.

text/plain

This is the default for textual files. Even if it really means «unknown textual file,» browsers assume they can display it.

Note: text/plain does not mean «any kind of textual data.» If they expect a specific kind of textual data, they will likely not consider it a match. Specifically if they download a text/plain file from a element declaring a CSS file, they will not recognize it as a valid CSS file if presented with text/plain . The CSS mime type text/css must be used.

text/css

CSS files used to style a Web page must be sent with text/css . If a server doesn’t recognize the .css suffix for CSS files, it may send them with text/plain or application/octet-stream MIME types. If so, they won’t be recognized as CSS by most browsers and will be ignored.

text/html

All HTML content should be served with this type. Alternative MIME types for XHTML (like application/xhtml+xml ) are mostly useless nowadays.

Note: Use application/xml or application/xhtml+xml if you want XML’s strict parsing rules, sections, or elements that aren’t from HTML/SVG/MathML namespaces.

text/javascript

Per the HTML specification, JavaScript files should always be served using the MIME type text/javascript . No other values are considered valid, and using any of those may result in scripts that do not load or run.

For historical reasons, the MIME Sniffing Standard (the definition of how browsers should interpret media types and figure out what to do with content that doesn’t have a valid one) allows JavaScript to be served using any MIME type that essentially matches any of the following:

• application/javascript
• application/ecmascript
• application/x-ecmascript
• application/x-javascript
• text/javascript
• text/ecmascript
• text/javascript1.0
• text/javascript1.1
• text/javascript1.2
• text/javascript1.3
• text/javascript1.4
• text/javascript1.5
• text/jscript
• text/livescript
• text/x-ecmascript
• text/x-javascript

Note: Even though any given user agent may support any or all of these, you should only use text/javascript . It’s the only MIME type guaranteed to work now and into the future.

Some content you find may have a charset parameter at the end of the text/javascript media type, to specify the character set used to represent the code’s content. This is not valid, and in most cases will result in a script not being loaded.

Image types

Files whose MIME type is image contain image data. The subtype specifies which specific image file format the data represents.

The following image types are used commonly enough to be considered safe for use on web pages:

• image/apng : Animated Portable Network Graphics (APNG)
• image/avif : AV1 Image File Format (AVIF)
• image/gif : Graphics Interchange Format (GIF)
• image/jpeg : Joint Photographic Expert Group image (JPEG)
• image/png : Portable Network Graphics (PNG)
• image/svg+xml : Scalable Vector Graphics (SVG)
• image/webp : Web Picture format (WEBP)

The Image file type and format guide provides information and recommendations about when to use the different image formats.

Audio and video types

Our media container formats guide provides a list of the file types that are commonly supported by web browsers, including information about what their special use cases may be, any drawbacks they have, and compatibility information, along with other details.

The audio codec and video codec guides list the various codecs that web browsers often support, providing compatibility details along with technical information such as how many audio channels they support, what sort of compression is used, and what bit rates and so forth they’re useful at. The codecs used by WebRTC guide expands upon this by specifically covering the codecs supported by the major web browsers, so you can choose the codecs that best cover the range of browsers you wish to support.

As for MIME types of audio or video files, they typically specify the container format (file type). The optional codecs parameter can be added to the MIME type to further specify which codecs to use and what options were used to encode the media, such as codec profile, level, or other such information.

The most commonly used MIME types used for web content are listed below. This isn’t a complete list of all the types that may be available, however. See the media container formats guide for that.

MIME type	Audio or video type
audio/wave audio/wav audio/x-wav audio/x-pn-wav	An audio file in the WAVE container format. The PCM audio codec (WAVE codec «1») is often supported, but other codecs have limited support (if any).
audio/webm	An audio file in the WebM container format. Vorbis and Opus are the codecs officially supported by the WebM specification.
video/webm	A video file, possibly with audio, in the WebM container format. VP8 and VP9 are the most common video codecs; Vorbis and Opus the most common audio codecs.
audio/ogg	An audio file in the Ogg container format. Vorbis is the most common audio codec used in such a container; however, Opus is now supported by Ogg as well.
video/ogg	A video file, possibly with audio, in the Ogg container format. Theora is the usual video codec used within it; Vorbis is the usual audio codec, although Opus is becoming more common.
application/ogg	An audio or video file using the Ogg container format. Theora is the usual video codec used within it; Vorbis is the usual audio codec.

multipart/form-data

The multipart/form-data type can be used when sending the values of a completed HTML Form from browser to server.

As a multipart document format, it consists of different parts, delimited by a boundary (a string starting with a double dash — ). Each part is its own entity with its own HTTP headers, Content-Disposition , and Content-Type for file uploading fields.

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Как определить тип MIME файла в android?

Предположим, у меня есть полный путь к файлу, например:(/sdcard/tlogo.формат PNG.) Я хочу знать его тип MIME.

Я создал функцию для его

но когда я вызываю его, он возвращает null.

21 ответов:

в первую очередь, вы должны рассмотреть вызова MimeTypeMap#getMimeTypeFromExtension() , например:

вышеуказанное решение MimeTypeMap возвращает значение null в моем использования. Это работает, и проще:

оптимальный вариант Йенс’ ответ с нулевой безопасностью и резервным типом.

важно: getFileExtensionFromUrl() работает только с строчные буквы!

обновление (19.03.2018)

бонус: выше методы как менее подробный функция расширения Котлина:

обратите супер пристальное внимание на umerk44 ‘ s решение выше. getMimeTypeFromExtension вызывает guessMimeTypeTypeFromExtension и чувствителен к регистру. Я потратил на это целый день, а потом присмотрелся — getMimeTypeFromExtension вернутся NULL Если вы ее пройдете «формат JPG», тогда как он будет возвращать «изображение/jpeg» если вы передадите это «формат JPG».

иногда ответы джеба и Йенса не работают и возвращают null. В этом случае я использую следующее решение. Глава файла обычно содержит подпись типа. Я читаю его и сравниваю с известным в список подписей.

signatureId — это индекс подписи в массиве подписей. Например,

Теперь у меня есть тип файла, даже если URI файла нет. Далее я получаю тип mime по типу файла. Если вы не знаете, какой тип mime получить, вы можете найти правильный в в этой таблице.

это работает для многих типов файлов. Но для видео это не работает, потому что вам нужно известный видеокодек, чтобы получить тип mime. Чтобы получить тип mime видео я использую MediaMetadataRetriever.

вот решение, которое я использовал в своем приложении для Android:

MimeTypeMap может не распознавать некоторые расширения файлов,такие как flv,mpeg,3gpp, cpp. Поэтому вам нужно подумать, как развернуть MimeTypeMap для поддержания вашего кода. Вот такой пример.

плюс, вот полный список типов MIME

в то время как из asset/file(обратите внимание, что несколько случаев отсутствуют в MimeTypeMap).

в то время как использование ContentResolver

в то время как http / https запрос

Я пытался использовать стандартные методы для определения типа mime, но я не могу сохранить расширение файла с помощью MimeTypeMap.getFileExtensionFromUrl(uri.getPath()). Этот метод вернул мне пустую строку. Поэтому я сделал нетривиальное решение, чтобы сохранить расширение файла.

вот метод возврата расширения файла

и сохранив расширение файла можно получить тип mime, как показано ниже

на Xamarin Android (из ответа @HoaLe выше)

вышеуказанное решение вернуло null в случае .rar-файл, используя URLConnection.guessContentTypeFromName (url) работал в этом случае.

у вас есть несколько вариантов, чтобы получить расширение файла: как: 1- String filename = uri.getLastPathSegment(); посмотреть этот ссылке

2-Вы можете использовать этот код также

но это не хорошо aproch. 3-Если у вас есть URI файла, то используйте этот код

4-Если у вас есть URL, то используйте этот код:

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