- java.lang.Object
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- javax.imageio.spi.IIOServiceProvider
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- javax.imageio.spi.ImageOutputStreamSpi
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- All Implemented Interfaces:
RegisterableService
public abstract class ImageOutputStreamSpi extends IIOServiceProvider
The service provider interface (SPI) forImageOutputStreams. For more information on service provider interfaces, see the class comment for theIIORegistryclass.This interface allows arbitrary objects to be "wrapped" by instances of
ImageOutputStream. For example, a particularImageOutputStreamSpimight allow a genericOutputStreamto be used as a destination; another might output to aFileor to a device such as a serial port.By treating the creation of
ImageOutputStreams as a pluggable service, it becomes possible to handle future output destinations without changing the API. Also, high-performance implementations ofImageOutputStream(for example, native implementations for a particular platform) can be installed and used transparently by applications.- See Also:
IIORegistry,ImageOutputStream
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Field Summary
Fields Modifier and Type Field Description protected Class<?>outputClassAClassobject indicating the legal object type for use by thecreateInputStreamInstancemethod.-
Fields declared in class javax.imageio.spi.IIOServiceProvider
vendorName, version
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Constructor Summary
Constructors Modifier Constructor Description protectedImageOutputStreamSpi()Constructs a blankImageOutputStreamSpi.ImageOutputStreamSpi(String vendorName, String version, Class<?> outputClass)Constructs anImageOutputStreamSpiwith a given set of values.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description booleancanUseCacheFile()Returnstrueif theImageOutputStreamimplementation associated with this service provider can optionally make use of a cacheFilefor improved performance and/or memory footrprint.ImageOutputStreamcreateOutputStreamInstance(Object output)Returns an instance of theImageOutputStreamimplementation associated with this service provider.abstract ImageOutputStreamcreateOutputStreamInstance(Object output, boolean useCache, File cacheDir)Returns an instance of theImageOutputStreamimplementation associated with this service provider.Class<?>getOutputClass()Returns aClassobject representing the class or interface type that must be implemented by an output destination in order to be "wrapped" in anImageOutputStreamvia thecreateOutputStreamInstancemethod.booleanneedsCacheFile()Returnstrueif theImageOutputStreamimplementation 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 Detail
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outputClass
protected Class<?> outputClass
AClassobject indicating the legal object type for use by thecreateInputStreamInstancemethod.
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Constructor Detail
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ImageOutputStreamSpi
protected ImageOutputStreamSpi()
Constructs a blankImageOutputStreamSpi. It is up to the subclass to initialize instance variables and/or override method implementations in order to provide working versions of all methods.
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ImageOutputStreamSpi
public ImageOutputStreamSpi(String vendorName, String version, Class<?> outputClass)
Constructs anImageOutputStreamSpiwith a given set of values.- Parameters:
vendorName- the vendor name.version- a version identifier.outputClass- aClassobject indicating the legal object type for use by thecreateOutputStreamInstancemethod.- Throws:
IllegalArgumentException- ifvendorNameisnull.IllegalArgumentException- ifversionisnull.
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Method Detail
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getOutputClass
public Class<?> getOutputClass()
Returns aClassobject representing the class or interface type that must be implemented by an output destination in order to be "wrapped" in anImageOutputStreamvia thecreateOutputStreamInstancemethod.Typical return values might include
OutputStream.classorFile.class, but any class may be used.- Returns:
- a
Classvariable. - See Also:
createOutputStreamInstance(Object, boolean, File)
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canUseCacheFile
public boolean canUseCacheFile()
Returnstrueif theImageOutputStreamimplementation associated with this service provider can optionally make use of a cacheFilefor improved performance and/or memory footrprint. Iffalse, the value of thecacheFileargument tocreateOutputStreamInstancewill be ignored.The default implementation returns
false.- Returns:
trueif a cache file can be used by the output streams created by this service provider.
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needsCacheFile
public boolean needsCacheFile()
Returnstrueif theImageOutputStreamimplementation associated with this service provider requires the use of a cacheFile.The default implementation returns
false.- Returns:
trueif a cache file is needed by the output streams created by this service provider.
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createOutputStreamInstance
public abstract ImageOutputStream createOutputStreamInstance(Object output, boolean useCache, File cacheDir) throws IOException
Returns an instance of theImageOutputStreamimplementation 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:
output- an object of the class type returned bygetOutputClass.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
ImageOutputStreaminstance. - Throws:
IllegalArgumentException- ifoutputis 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:
getOutputClass()
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createOutputStreamInstance
public ImageOutputStream createOutputStreamInstance(Object output) throws IOException
Returns an instance of theImageOutputStreamimplementation associated with this service provider. A cache file will be created in the system-dependent default temporary-file directory, if needed.- Parameters:
output- an object of the class type returned bygetOutputClass.- Returns:
- an
ImageOutputStreaminstance. - Throws:
IllegalArgumentException- ifoutputis not an instance of the correct class or isnull.IOException- if a cache file is needed but cannot be created.- See Also:
getOutputClass()
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