org.hd.d.pg2k.svrCore.MIME
Class ExhibitMIME

java.lang.Object
  org.hd.d.pg2k.svrCore.MIME.ExhibitMIME

public final class ExhibitMIME
extends java.lang.Object

Routines to establish/check exhibit MIME types. This is hard-wired into the Gallery for now; we don't allow dynamic loading of new types and handlers...

This is a rewrite and extension of the old (pre-PG2K) PG Attributes class.

DEFAULT_HANDLER_PACKAGE

public static final java.lang.String DEFAULT_HANDLER_PACKAGE

Package for default media handlers.

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ET_GIF

public static final int ET_GIF

Type of GIF file.

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ET_JPEG

public static final int ET_JPEG

Type of JPEG file.

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ET_AU

public static final int ET_AU

Type of Sun audio (usually 64kbps 8-bit u-law G.711) file.

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ET_MP2

public static final int ET_MP2

Type of MPEG-1 Layer-II audio file.

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ET_MP3

public static final int ET_MP3

Type of MPEG-1 or MPEG-2 or MPEG-2.5 Layer-III audio file (8kbps and up).

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ET_MP4

public static final int ET_MP4

Type of MPEG-4 audio file (2kbps and up).

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ET_MIDI

public static final int ET_MIDI

Type of General MIDI audio file.

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ET_WAV

public static final int ET_WAV

Type of WAV audio file.

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ET_HTMLFRAG

public static final int ET_HTMLFRAG

Type of HTML text fragment file.

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ET_MPEG

public static final int ET_MPEG

Type of MPEG video file.

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ET_TIFF

public static final int ET_TIFF

Type of TIFF image file.

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ET_BMP

public static final int ET_BMP

Type of BMP image file.

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ET_PPT

public static final int ET_PPT

Type of PowerPoint presentation file.

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ET_RM

public static final int ET_RM

Type of RealMedia file.

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ET_AVI

public static final int ET_AVI

Type of RealMedia file.

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ET_PNG

public static final int ET_PNG

Type of PNG (GIF-replacement) file.

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ET_MNG

public static final int ET_MNG

Type of MNG (GIF-replacement) file.

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ET_JP2

public static final int ET_JP2

Type of JPEG-2000 image file.

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ET_SWF

public static final int ET_SWF

Type of Flash file.

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ET_PDF

public static final int ET_PDF

Type of PDF file.

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ET_3GP

public static final int ET_3GP

Type of 3GPP file.

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ET_WMV

public static final int ET_WMV

Type of Windows Movie file.

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ET_RTF

public static final int ET_RTF

Type of Windows Rich Text Format file.

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ET_TRML

public static final int ET_TRML

Type of Gallery 'trail' marked-up text file.

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ET_ZIP

public static final int ET_ZIP

Type of ZIP archive file.

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ET_TGZ

public static final int ET_TGZ

Type of GZIPped tar archive file.

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ET_TBZ2

public static final int ET_TBZ2

Type of BZIP2ed tar archive file.

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ET_MOV

public static final int ET_MOV

Type of QuickTime movie file.

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ET__min

public static final int ET__min

Minimum valid ET_XXX value (these values may be sparse). Guaranteed strictly positive.

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ET__max

public static final int ET__max

Maximum valid ET_XXX value (these values may be sparse). Guaranteed to be no less than ET__min.

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inputFileTypes

private static final ExhibitMIME.ExhibitTypeParameters[] inputFileTypes

File types accepted by (and generated by) the Gallery. Not to be handed outside the gallery in this raw state. Not necessarily in numeric order at construction here, but sorted as part of the static initialiser.

_iVIFE_cache

private static final java.util.Hashtable<java.lang.String,ExhibitMIME.ExhibitTypeParameters> _iVIFE_cache

Private cache of mappings from extension to parameters. Used by isValidInputExhibitNameExtension(), and filled in under protection of its own lock on first use if zero-sized.

Fixed small size.

_gET_cache

private static final java.util.Hashtable<java.lang.String,ExhibitMIME.ExhibitTypeParameters> _gET_cache

Private cache of mappings from extension to parameters. Used by isValidInputExhibitNameExtension(), and filled in under protection of its own lock on first use if zero-sized.

Fixed small size.

longestMagicBytes

private static volatile int longestMagicBytes

The longest known magic number in bytes of any exhibit type supported; strictly positive once computed. Volatile to allow access without a lock.

Computed on first use.

_gFPBT_cache

private static ExhibitMIME.ExhibitTypeParameters[] _gFPBT_cache

Private cache of mappings from type to parameters. Constructed on first use by getParamsByType().

Fixed small size.

ExhibitMIME

public ExhibitMIME()

getAllValidExhibitTypes

public static ExhibitMIME.ExhibitTypeParameters[] getAllValidExhibitTypes()

Returns a (private) list of all valid exhibit types, in order by type.

isValidInputExhibitNameExtension

public static ExhibitMIME.ExhibitTypeParameters isValidInputExhibitNameExtension(java.lang.CharSequence extension)

Checks if the extension of the (putative) exhibit name is a recognised input extension. The string should not be null, nor start with a dot. (A null input gives a null return.)

This returns null if the extension is not recognised, else the (immutable) ExhibitTypeParameters describing it.

getExhibitType

public static ExhibitMIME.ExhibitTypeParameters getExhibitType(java.lang.String extension)

Gets type of an exhibit given its extension. The string passed must not be null, nor start with a dot.

This returns null if the extension is not recognised, else the (immutable) ExhibitTypeParameters describing the exhibit type.

This checks first by the primary suffix for each exhibit type, but if that fails may check by secondary suffix.

magicOK

public static boolean magicOK(ExhibitMIME.ExhibitTypeParameters etp,
                              java.io.InputStream exhibitByteStream)

Verifies the magic number for a given exhibit. This will try to read enough data to check the magic number.

Returns false if the magic number check fails.

If the file type specified has no unique magic number to be checked this always succeeds.

This function does not close the input stream.

Parameters:

etp - is the exhibit type (must not be null)

exhibitByteStream - is a stream of bytes from the start of the exhibit at least long enough to contain the magic number

checkMagicOK

public static void checkMagicOK(ExhibitMIME.ExhibitTypeParameters etp,
                                java.io.File file)
                         throws java.io.IOException,
                                java.io.InvalidObjectException

Checks that file has expected magic number; throws IOException if not.

Throws:

java.io.InvalidObjectException - if given file does not have a correct magic number

java.io.IOException - in case of difficulty reading the file

getLongestMagicBytes

public static int getLongestMagicBytes()

Get longest known magic number in bytes of any exhibit type supported; strictly positive.

guessTypeFromMagic

public static ExhibitMIME.ExhibitTypeParameters guessTypeFromMagic(java.io.InputStream is)
                                                            throws java.io.IOException

Guesses the type of a file/exhibit from its magic number, or null if unrecognisable. This may only be able to check for files that have a unique magic number.

The stream may need to be markable to allow various possibilities to be tested.

Throws:

java.io.IOException

getInputFileType

public static ExhibitMIME.ExhibitTypeParameters getInputFileType(java.lang.CharSequence name)

Gets the type of a file from its name, or null if unrecognised here. The string passed must not be null, nor start with a dot.

This returns null if the extension is not recognised for an exhibit, else returns the (immutable) ExhibitTypeParameters describing it.

The extension should be for an exhibit input, though this can be called to quickly check if a filename or URI might be for an exhibit, returning null if not.

Parameters:

name - name of file or URL/URI

getParamsByType

public static ExhibitMIME.ExhibitTypeParameters getParamsByType(int type)

Given an ET_XXX type, returns the ExhibitTypeParameters. Throws IllegalArgumentException for an illegal type.

getMIMEType

public static java.lang.String getMIMEType(java.lang.CharSequence name)
                                    throws java.io.IOException

Get the MIME type of an exhibit (even at the end of filename or URI or URL) from its name; never null nor "".

Throws:

java.io.IOException