Class ImageInputStreamSpi
- All Implemented Interfaces:
RegisterableService
ImageInputStreams. For more information on service
provider interfaces, see the class comment for the
IIORegistry class.
This interface allows arbitrary objects to be "wrapped" by
instances of ImageInputStream. For example,
a particular ImageInputStreamSpi might allow
a generic InputStream to be used as an input source;
another might take input from a URL.
By treating the creation of ImageInputStreams as a
pluggable service, it becomes possible to handle future input
sources without changing the API. Also, high-performance
implementations of ImageInputStream (for example,
native implementations for a particular platform) can be installed
and used transparently by applications.
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected Class<?> AClassobject indicating the legal object type for use by thecreateInputStreamInstancemethod.Fields declared in class javax.imageio.spi.IIOServiceProvider
vendorName, version -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedConstructs a blankImageInputStreamSpi.ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass) Constructs anImageInputStreamSpiwith a given set of values. -
Method Summary
Modifier and TypeMethodDescriptionbooleanReturnstrueif theImageInputStreamimplementation associated with this service provider can optionally make use of a cache file for improved performance and/or memory footrprint.createInputStreamInstance(Object input) Returns an instance of theImageInputStreamimplementation associated with this service provider.abstract ImageInputStreamcreateInputStreamInstance(Object input, boolean useCache, File cacheDir) Returns an instance of theImageInputStreamimplementation associated with this service provider.Class<?> Returns aClassobject representing the class or interface type that must be implemented by an input source in order to be "wrapped" in anImageInputStreamvia thecreateInputStreamInstancemethod.booleanReturnstrueif theImageInputStreamimplementation associated with this service provider requires the use of a cacheFile.Methods declared in class javax.imageio.spi.IIOServiceProvider
getDescription, getVendorName, getVersion, onDeregistration, onRegistration
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Field Details
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inputClass
AClassobject indicating the legal object type for use by thecreateInputStreamInstancemethod.
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Constructor Details
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ImageInputStreamSpi
protected ImageInputStreamSpi()Constructs a blankImageInputStreamSpi. It is up to the subclass to initialize instance variables and/or override method implementations in order to provide working versions of all methods. -
ImageInputStreamSpi
Constructs anImageInputStreamSpiwith a given set of values.- Parameters:
vendorName- the vendor name.version- a version identifier.inputClass- aClassobject indicating the legal object type for use by thecreateInputStreamInstancemethod.- Throws:
IllegalArgumentException- ifvendorNameisnull.IllegalArgumentException- ifversionisnull.
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Method Details
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getInputClass
Returns aClassobject representing the class or interface type that must be implemented by an input source in order to be "wrapped" in anImageInputStreamvia thecreateInputStreamInstancemethod.Typical return values might include
InputStream.classorURL.class, but any class may be used.- Returns:
- a
Classvariable. - See Also:
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canUseCacheFile
public boolean canUseCacheFile()Returnstrueif theImageInputStreamimplementation associated with this service provider can optionally make use of a cache file for improved performance and/or memory footrprint. Iffalse, the value of theuseCacheargument tocreateInputStreamInstancewill be ignored.The default implementation returns
false.- Returns:
trueif a cache file can be used by the input streams created by this service provider.
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needsCacheFile
public boolean needsCacheFile()Returnstrueif theImageInputStreamimplementation associated with this service provider requires the use of a cacheFile. Iftrue, the value of theuseCacheargument tocreateInputStreamInstancewill be ignored.The default implementation returns
false.- Returns:
trueif a cache file is needed by the input streams created by this service provider.
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createInputStreamInstance
public abstract ImageInputStream createInputStreamInstance(Object input, boolean useCache, File cacheDir) throws IOException Returns an instance of theImageInputStreamimplementation associated with this service provider. If the use of a cache file is optional, theuseCacheparameter will be consulted. Where a cache is required, or not applicable, the value ofuseCachewill be ignored.- Parameters:
input- an object of the class type returned bygetInputClass.useCache- abooleanindicating whether a cache file should be used, in cases where it is optional.cacheDir- aFileindicating where the cache file should be created, ornullto use the system directory.- Returns:
- an
ImageInputStreaminstance. - Throws:
IllegalArgumentException- ifinputis not an instance of the correct class or isnull.IllegalArgumentException- if a cache file is needed butcacheDiris non-nulland is not a directory.IOException- if a cache file is needed but cannot be created.- See Also:
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createInputStreamInstance
Returns an instance of theImageInputStreamimplementation associated with this service provider. A cache file will be created in the system-dependent default temporary-file directory, if needed.- Parameters:
input- an object of the class type returned bygetInputClass.- Returns:
- an
ImageInputStreaminstance. - Throws:
IllegalArgumentException- ifinputis not an instance of the correct class or isnull.IOException- if a cache file is needed but cannot be created.- See Also:
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