eu.medsea.mimeutil
Class MimeUtil

java.lang.Object
  eu.medsea.mimeutil.MimeUtil

public class MimeUtil
extends Object

NOTE: Since version 2.1 this class delegates ALL calls to a static instance of the new MimeUtil2 implementation.

Author:

Steven McArdle.

See Also:

The MimeUtil utility is a utility class that allows applications to detect, work with and manipulate MIME types.

A MIME or "Multipurpose Internet Mail Extension" type is an Internet standard that is important outside of just e-mail use. MIME is used extensively in other communications protocols such as HTTP for web communications. IANA "Internet Assigned Numbers Authority" is responsible for the standardisation and publication of MIME types. Basically any resource on any computer that can be located via a URI can be assigned a mime type. So for instance, JPEG images have a MIME type of image/jpg. Some resources can have multiple MIME types associated with them such as files with an XML extension have the MIME types text/xml and application/xml and even specialised versions of xml such as image/svg+xml for SVG image files.

To do this MimeUtil uses registered MimeDetector(s) that are delegated to in sequence to actually perform the detection. There a several MimeDetector implementations that come with the utility and you can register and unregister them to perform detection based on file extensions, file globing and magic number detection.
Their is also a fourth MimeDetector that is registered by default that detects text files and encodings. Unlike the other MimeDetector(s) or any MimeDetector(s) you may choose to implement, the TextMimeDetector cannot be registered or unregistered by your code. It is advisable that you read the java doc for the TextMimeDetector as it can be modified in several ways to make it perform better and or detect more specific types.
Please refer to the java doc for each of these MimeDetector(s) for a description of how they actually perform their particular detection process.

It is important to note that MIME matching is not an exact science, meaning that a positive match does not guarantee that the returned MIME type is actually correct. It is a best guess method of matching and the matched MIME types should be used with this in mind.

New MimeDetector(s) can easily be created and registered with MimeUtil to extend it's functionality beyond these initial detection strategies by extending the AbstractMimeDetector class. To see how to implement your own MimeDetector take a look at the java doc and source code for the {@link ExtensionMimeDetector}, {@link MagicMimeMimeDetector} and {@link OpendesktopMimeDetector} classes. To register and unregister MimeDetector(s) use the [un]registerMimeDetector(...) methods of this class.

The order that the MimeDetector(s) are executed is defined by the order each MimeDetector is registered.

The resulting Collection of MIME types returned in response to a getMimeTypes(...) call is a normalised list of the accumulation of MIME types returned by each of the registered MimeDetector(s) that implement the specified getMimeTypesXXX(...) methods.

All methods in this class that return a Collection object containing MimeType(s) actually return a {@link MimeTypeHashSet} that implements both the {@link Set} and {@link Collection} interfaces.

Constructor Summary

MimeUtil()

Method Summary

static void	addKnownMimeType(MimeType mimeType) While MimeType(s) are being loaded by the MimeDetector(s) they should be added to the list of known MIME types.
static void	addKnownMimeType(String mimeType) While MimeType(s) are being loaded by the MimeDetector(s) they should be added to the list of known MIME types.
static String	getExtension(File file) Get the extension part of a file name defined by the file parameter.
static String	getExtension(String fileName) Get the extension part of a file name defined by the fileName parameter.
static MimeType	getFirstMimeType(String mimeTypes) Get the first in a comma separated list of mime types.
static InputStream	getInputStreamForURL(URL url) Utility method to get the InputStream from a URL.
static String	getMediaType(String mimeType) Utility method to get the major or media part of a mime type i.e.
static MimeDetector	getMimeDetector(String name) Get a registered MimeDetector by name.
static double	getMimeQuality(String mimeType) Utility method to get the quality part of a mime type.
static Collection	getMimeTypes(byte[] data) Get a Collection of possible MimeType(s) that this byte array could represent according to the registered MimeDetector(s).
static Collection	getMimeTypes(byte[] data, MimeType unknownMimeType) Get a Collection of possible MimeType(s) that this byte array could represent according to the registered MimeDetector(s).
static Collection	getMimeTypes(File file) Get all of the matching mime types for this file object.
static Collection	getMimeTypes(File file, MimeType unknownMimeType) Get all of the matching mime types for this file object.
static Collection	getMimeTypes(InputStream in) Get all of the matching mime types for this InputStream object.
static Collection	getMimeTypes(InputStream in, MimeType unknownMimeType) Get all of the matching mime types for this InputStream object.
static Collection	getMimeTypes(String fileName) Get all of the matching mime types for this file name.
static Collection	getMimeTypes(String fileName, MimeType unknownMimeType) Get all of the matching mime types for this file name .
static Collection	getMimeTypes(URL url) Get all of the matching mime types for this URL object.
static Collection	getMimeTypes(URL url, MimeType unknownMimeType)
static MimeType	getMostSpecificMimeType(Collection mimeTypes) Get the most specific match of the Collection of mime types passed in.
static ByteOrder	getNativeOrder() Get the native byte order of the OS on which you are running.
static MimeType	getPreferedMimeType(String accept, String canProvide) Gives you the best match for your requirements.
static double	getQuality(String mimeType) Get the quality parameter of this mime type i.e.
static String	getSubType(String mimeType) Utility method to get the minor part of a mime type i.e.
static boolean	isMimeTypeKnown(MimeType mimeType) Check to see if this mime type is one of the types seen during initialisation or has been added at some later stage using addKnownMimeType(...)
static boolean	isMimeTypeKnown(String mimeType) Check to see if this mime type is one of the types seen during initialisation or has been added at some later stage using addKnownMimeType(...)
static boolean	isTextMimeType(MimeType mimeType) Utility convenience method to check if a particular MimeType instance is actually a TextMimeType.
static MimeDetector	registerMimeDetector(String mimeDetector) Register a MimeDetector and add it to the MimeDetector registry.
static MimeDetector	unregisterMimeDetector(MimeDetector mimeDetector) Remove a previously registered MimeDetector
static MimeDetector	unregisterMimeDetector(String mimeDetector) Remove a previously registered MimeDetector

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MimeUtil

public MimeUtil()

Method Detail

addKnownMimeType

public static void addKnownMimeType(MimeType mimeType)

While MimeType(s) are being loaded by the MimeDetector(s) they should be added to the list of known MIME types. It is not mandatory for MimeDetector(s) to do so but they should where possible so that the list is as complete as possible. You can add other MIME types to this list using this method. You can then use the isMimeTypeKnown(...) utility methods to see if a MIME type you have matches one that the utility has already seen.

This can be used to limit the mime types you work with i.e. if its not been loaded then don't bother using it as it won't match. This is no guarantee that a match will not be found as it is possible that a particular MimeDetector does not have an initialisation phase that loads all of the MIME types it will match.

For instance if you had a MIME type of abc/xyz and passed this to isMimeTypeKnown(...) it would return false unless you specifically add this to the know MIME types using this method.

Parameters:

mimeType - a MIME type you want to add to the known MIME types. Duplicates are ignored.

See Also:

isMimeTypeKnown(String mimeType), isMimeTypeKnown(MimeType mimetType)

addKnownMimeType

public static void addKnownMimeType(String mimeType)

While MimeType(s) are being loaded by the MimeDetector(s) they should be added to the list of known MIME types. It is not mandatory for MimeDetector(s) to do so but they should where possible so that the list is as complete as possible. You can add other MIME types to this list using this method. You can then use the isMimeTypeKnown(...) utility methods to see if a MIME type you have matches one that the utility has already seen.

This can be used to limit the mime types you work with i.e. if its not been loaded then don't bother using it as it won't match. This is no guarantee that a match will not be found as it is possible that a particular MimeDetector does not have an initialisation phase that loads all of the MIME types it will match.

For instance if you had a MIME type of abc/xyz and passed this to isMimeTypeKnown(...) it would return false unless you specifically add this to the know MIME types using this method.

Parameters:

mimeType - a MIME type you want to add to the known MIME types. Duplicates are ignored.

See Also:

isMimeTypeKnown(String mimetype), isMimeTypeKnown(MimeType mimetType)

registerMimeDetector

public static MimeDetector registerMimeDetector(String mimeDetector)

Register a MimeDetector and add it to the MimeDetector registry. MimeDetector(s) are effectively singletons as they are keyed against their fully qualified class name.

Parameters:

mimeDetector. - This must be the fully qualified name of a concrete instance of an AbstractMimeDetector class. This enforces that all custom MimeDetector(s) extend the AbstractMimeDetector.

See Also:

MimeDetector

getExtension

public static String getExtension(File file)

Get the extension part of a file name defined by the file parameter.

Parameters:

file - a file object

Returns:

the file extension or null if it does not have one.

getExtension

public static String getExtension(String fileName)

Get the extension part of a file name defined by the fileName parameter. There may be no extension or it could be a single part extension such as .bat or a multi-part extension such as .tar.gz

Parameters:

fileName - a relative or absolute path to a file

Returns:

the file extension or null if it does not have one.

getFirstMimeType

public static MimeType getFirstMimeType(String mimeTypes)

Get the first in a comma separated list of mime types. Useful when using extension mapping that can return multiple mime types separate by commas and you only want the first one.

Parameters:

mimeTypes - comma separated list of mime types

Returns:

first in a comma separated list of mime types or null if the mimeTypes string is null or empty

getMediaType

public static String getMediaType(String mimeType)
                           throws MimeException

Utility method to get the major or media part of a mime type i.e. the part before the '/' character

Parameters:

mimeType - you want to get the media part from

Returns:

media type of the mime type

Throws:

MimeException - if you pass in an invalid mime type structure

getMimeQuality

public static double getMimeQuality(String mimeType)
                             throws MimeException

Utility method to get the quality part of a mime type. If it does not exist then it is always set to q=1.0 unless it's a wild card. For the major component wild card the value is set to 0.01 For the minor component wild card the value is set to 0.02

Thanks to the Apache organisation for these settings.

Parameters:

mimeType - a valid mime type string with or without a valid q parameter

Returns:

the quality value of the mime type either calculated from the rules above or the actual value defined.

Throws:

MimeException - this is thrown if the mime type pattern is invalid.

getMimeDetector

public static MimeDetector getMimeDetector(String name)

Get a registered MimeDetector by name.

Parameters:

name - the name of a registered MimeDetector. This is always the fully qualified name of the class implementing the MimeDetector.

Returns:

getMimeTypes

public static final Collection getMimeTypes(byte[] data)
                                     throws MimeException

Get a Collection of possible MimeType(s) that this byte array could represent according to the registered MimeDetector(s). If no MimeType(s) are detected then the returned Collection will contain only the UNKNOWN_MIME_TYPE

Parameters:

data -

Returns:

all matching MimeType(s)

Throws:

MimeException

getMimeTypes

public static final Collection getMimeTypes(byte[] data,
                                            MimeType unknownMimeType)
                                     throws MimeException

Get a Collection of possible MimeType(s) that this byte array could represent according to the registered MimeDetector(s). If no MimeType(s) are detected then the returned Collection will contain only the passed in unknownMimeType

Parameters:

data -

unknownMimeType - used if the registered MimeDetector(s) fail to match any MimeType(s)

Returns:

all matching MimeType(s)

Throws:

MimeException

getMimeTypes

public static final Collection getMimeTypes(File file)
                                     throws MimeException

Get all of the matching mime types for this file object. The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the default UNKNOWN_MIME_TYPE

Parameters:

file - the File object to detect.

Returns:

collection of matching MimeType(s)

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(File file,
                                            MimeType unknownMimeType)
                                     throws MimeException

Get all of the matching mime types for this file object. The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the unknownMimeType passed in.

Parameters:

file - the File object to detect.

unknownMimeType. -

Returns:

the Collection of matching mime types. If the collection would be empty i.e. no matches then this will contain the passed in parameter unknownMimeType

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(InputStream in)
                                     throws MimeException

Get all of the matching mime types for this InputStream object. The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the default UNKNOWN_MIME_TYPE

Parameters:

in - InputStream to detect.

Returns:

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(InputStream in,
                                            MimeType unknownMimeType)
                                     throws MimeException

Get all of the matching mime types for this InputStream object. The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the unknownMimeType passed in.

Parameters:

in - the InputStream object to detect.

unknownMimeType. -

Returns:

the Collection of matching mime types. If the collection would be empty i.e. no matches then this will contain the passed in parameter unknownMimeType

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(String fileName)
                                     throws MimeException

Get all of the matching mime types for this file name. The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the default UNKNOWN_MIME_TYPE

Parameters:

fileName - the name of a file to detect.

Returns:

collection of matching MimeType(s)

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(String fileName,
                                            MimeType unknownMimeType)
                                     throws MimeException

Get all of the matching mime types for this file name . The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the unknownMimeType passed in.

Parameters:

fileName - the name of a file to detect.

unknownMimeType. -

Returns:

the Collection of matching mime types. If the collection would be empty i.e. no matches then this will contain the passed in parameter unknownMimeType

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(URL url)
                                     throws MimeException

Get all of the matching mime types for this URL object. The method delegates down to each of the registered MimeHandler(s) and returns a normalised list of all matching mime types. If no matching mime types are found the returned Collection will contain the default UNKNOWN_MIME_TYPE

Parameters:

url - a URL to detect.

Returns:

Collection of matching MimeType(s)

Throws:

MimeException - if there are problems such as reading files generated when the MimeHandler(s) executed.

getMimeTypes

public static final Collection getMimeTypes(URL url,
                                            MimeType unknownMimeType)
                                     throws MimeException

Throws:

MimeException

getNativeOrder

public static ByteOrder getNativeOrder()

Get the native byte order of the OS on which you are running. It will be either big or little endian. This is used internally for the magic mime rules mapping.

Returns:

ByteOrder

getPreferedMimeType

public static MimeType getPreferedMimeType(String accept,
                                           String canProvide)

Gives you the best match for your requirements.

You can pass the accept header from a browser request to this method along with a comma separated list of possible mime types returned from say getExtensionMimeTypes(...) and the best match according to the accept header will be returned.

The following is typical of what may be specified in an HTTP Accept header:

Accept: text/xml, application/xml, application/xhtml+xml, text/html;q=0.9, text/plain;q=0.8, video/x-mng, image/png, image/jpeg, image/gif;q=0.2, text/css, */*;q=0.1

The quality parameter (q) indicates how well the user agent handles the MIME type. A value of 1 indicates the MIME type is understood perfectly, and a value of 0 indicates the MIME type isn't understood at all.

The reason the image/gif MIME type contains a quality parameter of 0.2, is to indicate that PNG & JPEG are preferred over GIF if the server is using content negotiation to deliver either a PNG or a GIF to user agents. Similarly, the text/html quality parameter has been lowered a little, to ensure that the XML MIME types are given in preference if content negotiation is being used to serve an XHTML document.

Parameters:

accept - is a comma separated list of mime types you can accept including QoS parameters. Can pass the Accept: header directly.

canProvide - is a comma separated list of mime types that can be provided such as that returned from a call to getExtensionMimeTypes(...)

Returns:

the best matching mime type possible.

getMostSpecificMimeType

public static MimeType getMostSpecificMimeType(Collection mimeTypes)

Get the most specific match of the Collection of mime types passed in. The Collection

Parameters:

mimeTypes - this should be the Collection of mime types returned from a getMimeTypes(...) call.

Returns:

the most specific MimeType. If more than one of the mime types in the Collection have the same value then the first one found with this value in the Collection is returned.

getSubType

public static String getSubType(String mimeType)
                         throws MimeException

Utility method to get the minor part of a mime type i.e. the bit after the '/' character

Parameters:

mimeType - you want to get the minor part from

Returns:

sub type of the mime type

Throws:

MimeException - if you pass in an invalid mime type structure

isMimeTypeKnown

public static boolean isMimeTypeKnown(MimeType mimeType)

Check to see if this mime type is one of the types seen during initialisation or has been added at some later stage using addKnownMimeType(...)

Parameters:

mimeType -

Returns:

true if the mimeType is in the list else false is returned

See Also:

addKnownMimeType(String mimetype)

isMimeTypeKnown

public static boolean isMimeTypeKnown(String mimeType)

Check to see if this mime type is one of the types seen during initialisation or has been added at some later stage using addKnownMimeType(...)

Parameters:

mimeType -

Returns:

true if the mimeType is in the list else false is returned

See Also:

addKnownMimeType(String mimetype)

isTextMimeType

public static boolean isTextMimeType(MimeType mimeType)

Utility convenience method to check if a particular MimeType instance is actually a TextMimeType. Used when iterating over a collection of MimeType's to help with casting to enable access the the TextMimeType methods not available to a standard MimeType. Can also use instanceof.

Parameters:

mimeType -

Returns:

true if the passed in instance is a TextMimeType

See Also:

MimeType, TextMimeType

unregisterMimeDetector

public static MimeDetector unregisterMimeDetector(MimeDetector mimeDetector)

Remove a previously registered MimeDetector

Parameters:

mimeDetector -

Returns:

the MimeDetector that was removed from the registry else null.

unregisterMimeDetector

public static MimeDetector unregisterMimeDetector(String mimeDetector)

Remove a previously registered MimeDetector

Parameters:

mimeDetector -

Returns:

the MimeDetector that was removed from the registry else null.

getQuality

public static double getQuality(String mimeType)
                         throws MimeException

Get the quality parameter of this mime type i.e. the q= property. This method implements a value system similar to that used by the apache server i.e. if the media type is a * then it's q value is set to 0.01 and if the sub type is a * then the q value is set to 0.02 unless a specific q value is specified. If a q property is set it is limited to a max value of 1.0

Parameters:

mimeType -

Returns:

the quality value as a double between 0.0 and 1.0

Throws:

MimeException

getInputStreamForURL

public static InputStream getInputStreamForURL(URL url)
                                        throws Exception

Utility method to get the InputStream from a URL. Handles several schemes, for instance, if the URL points to a jar entry it will get a proper usable stream from the URL

Parameters:

url -

Returns:

Throws:

Exception