- java.lang.Object
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- javax.imageio.spi.IIOServiceProvider
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- javax.imageio.spi.ImageInputStreamSpi
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- All Implemented Interfaces:
- RegisterableService
public abstract class ImageInputStreamSpi extends IIOServiceProvider
The service provider interface (SPI) forImageInputStream
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
ImageInputStream
. For example, a particularImageInputStreamSpi
might allow a genericInputStream
to be used as an input source; another might take input from aURL
.By treating the creation of
ImageInputStream
s as a pluggable service, it becomes possible to handle future input sources without changing the API. Also, high-performance implementations ofImageInputStream
(for example, native implementations for a particular platform) can be installed and used transparently by applications.- See Also:
IIORegistry
,ImageInputStream
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Field Summary
Fields Modifier and Type Field and Description protected Class<?>
inputClass
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
ImageInputStreamSpi()
Constructs a blankImageInputStreamSpi
.ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass)
Constructs anImageInputStreamSpi
with a given set of values.
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Method Summary
Methods Modifier and Type Method and Description boolean
canUseCacheFile()
Returnstrue
if theImageInputStream
implementation associated with this service provider can optionally make use of a cache file for improved performance and/or memory footrprint.ImageInputStream
createInputStreamInstance(Object input)
Returns an instance of theImageInputStream
implementation associated with this service provider.abstract ImageInputStream
createInputStreamInstance(Object input, boolean useCache, File cacheDir)
Returns an instance of theImageInputStream
implementation associated with this service provider.Class<?>
getInputClass()
Returns aClass
object representing the class or interface type that must be implemented by an input source in order to be "wrapped" in anImageInputStream
via thecreateInputStreamInstance
method.boolean
needsCacheFile()
Returnstrue
if theImageInputStream
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
-
inputClass
protected Class<?> inputClass
AClass
object indicating the legal object type for use by thecreateInputStreamInstance
method.
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Constructor Detail
-
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
public ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass)
Constructs anImageInputStreamSpi
with a given set of values.- Parameters:
vendorName
- the vendor name.version
- a version identifier.inputClass
- aClass
object indicating the legal object type for use by thecreateInputStreamInstance
method.- Throws:
IllegalArgumentException
- ifvendorName
isnull
.IllegalArgumentException
- ifversion
isnull
.
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Method Detail
-
getInputClass
public Class<?> getInputClass()
Returns aClass
object representing the class or interface type that must be implemented by an input source in order to be "wrapped" in anImageInputStream
via thecreateInputStreamInstance
method.Typical return values might include
InputStream.class
orURL.class
, but any class may be used.- Returns:
- a
Class
variable. - See Also:
createInputStreamInstance(Object, boolean, File)
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canUseCacheFile
public boolean canUseCacheFile()
Returnstrue
if theImageInputStream
implementation associated with this service provider can optionally make use of a cache file for improved performance and/or memory footrprint. Iffalse
, the value of theuseCache
argument tocreateInputStreamInstance
will be ignored.The default implementation returns
false
.- Returns:
true
if a cache file can be used by the input streams created by this service provider.
-
needsCacheFile
public boolean needsCacheFile()
Returnstrue
if theImageInputStream
implementation associated with this service provider requires the use of a cacheFile
. Iftrue
, the value of theuseCache
argument tocreateInputStreamInstance
will be ignored.The default implementation returns
false
.- Returns:
true
if 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 theImageInputStream
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:
input
- an object of the class type returned bygetInputClass
.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
ImageInputStream
instance. - Throws:
IllegalArgumentException
- ifinput
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:
getInputClass()
,canUseCacheFile()
,needsCacheFile()
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createInputStreamInstance
public ImageInputStream createInputStreamInstance(Object input) throws IOException
Returns an instance of theImageInputStream
implementation 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
ImageInputStream
instance. - Throws:
IllegalArgumentException
- ifinput
is not an instance of the correct class or isnull
.IOException
- if a cache file is needed but cannot be created.- See Also:
getInputClass()
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