- 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) forImageOutputStream
s. For more information on service provider interfaces, see the class comment for theIIORegistry
class.This interface allows arbitrary objects to be "wrapped" by instances of
ImageOutputStream
. For example, a particularImageOutputStreamSpi
might allow a genericOutputStream
to be used as a destination; another might output to aFile
or to a device such as a serial port.By treating the creation of
ImageOutputStream
s 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 and Description protected Class<?>
outputClass
AClass
object indicating the legal object type for use by thecreateInputStreamInstance
method.-
Fields inherited from class javax.imageio.spi.IIOServiceProvider
vendorName, version
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Constructor Summary
Constructors Modifier Constructor and Description protected
ImageOutputStreamSpi()
Constructs a blankImageOutputStreamSpi
.ImageOutputStreamSpi(String vendorName, String version, Class<?> outputClass)
Constructs anImageOutputStreamSpi
with a given set of values.
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Method Summary
Methods Modifier and Type Method and Description boolean
canUseCacheFile()
Returnstrue
if theImageOutputStream
implementation associated with this service provider can optionally make use of a cacheFile
for improved performance and/or memory footrprint.ImageOutputStream
createOutputStreamInstance(Object output)
Returns an instance of theImageOutputStream
implementation associated with this service provider.abstract ImageOutputStream
createOutputStreamInstance(Object output, boolean useCache, File cacheDir)
Returns an instance of theImageOutputStream
implementation associated with this service provider.Class<?>
getOutputClass()
Returns aClass
object representing the class or interface type that must be implemented by an output destination in order to be "wrapped" in anImageOutputStream
via thecreateOutputStreamInstance
method.boolean
needsCacheFile()
Returnstrue
if theImageOutputStream
implementation associated with this service provider requires the use of a cacheFile
.-
Methods inherited from class javax.imageio.spi.IIOServiceProvider
getDescription, getVendorName, getVersion, onDeregistration, onRegistration
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Field Detail
-
outputClass
protected Class<?> outputClass
AClass
object indicating the legal object type for use by thecreateInputStreamInstance
method.
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Constructor Detail
-
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.
-
ImageOutputStreamSpi
public ImageOutputStreamSpi(String vendorName, String version, Class<?> outputClass)
Constructs anImageOutputStreamSpi
with a given set of values.- Parameters:
vendorName
- the vendor name.version
- a version identifier.outputClass
- aClass
object indicating the legal object type for use by thecreateOutputStreamInstance
method.- Throws:
IllegalArgumentException
- ifvendorName
isnull
.IllegalArgumentException
- ifversion
isnull
.
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Method Detail
-
getOutputClass
public Class<?> getOutputClass()
Returns aClass
object representing the class or interface type that must be implemented by an output destination in order to be "wrapped" in anImageOutputStream
via thecreateOutputStreamInstance
method.Typical return values might include
OutputStream.class
orFile.class
, but any class may be used.- Returns:
- a
Class
variable. - See Also:
createOutputStreamInstance(Object, boolean, File)
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canUseCacheFile
public boolean canUseCacheFile()
Returnstrue
if theImageOutputStream
implementation associated with this service provider can optionally make use of a cacheFile
for improved performance and/or memory footrprint. Iffalse
, the value of thecacheFile
argument tocreateOutputStreamInstance
will be ignored.The default implementation returns
false
.- Returns:
true
if a cache file can be used by the output streams created by this service provider.
-
needsCacheFile
public boolean needsCacheFile()
Returnstrue
if theImageOutputStream
implementation associated with this service provider requires the use of a cacheFile
.The default implementation returns
false
.- Returns:
true
if a cache file is needed by the output streams created by this service provider.
-
createOutputStreamInstance
public abstract ImageOutputStream createOutputStreamInstance(Object output, boolean useCache, File cacheDir) throws IOException
Returns an instance of theImageOutputStream
implementation associated with this service provider. If the use of a cache file is optional, theuseCache
parameter will be consulted. Where a cache is required, or not applicable, the value ofuseCache
will be ignored.- Parameters:
output
- an object of the class type returned bygetOutputClass
.useCache
- aboolean
indicating whether a cache file should be used, in cases where it is optional.cacheDir
- aFile
indicating where the cache file should be created, ornull
to use the system directory.- Returns:
- an
ImageOutputStream
instance. - Throws:
IllegalArgumentException
- ifoutput
is not an instance of the correct class or isnull
.IllegalArgumentException
- if a cache file is needed, butcacheDir
is non-null
and 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 theImageOutputStream
implementation 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
ImageOutputStream
instance. - Throws:
IllegalArgumentException
- ifoutput
is 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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