RegisterableService
public abstract class ImageInputStreamSpi extends IIOServiceProvider
ImageInputStream
s. 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 ImageInputStream
s 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.
Modifier and Type | Field | Description |
---|---|---|
protected Class |
inputClass |
A Class object indicating the legal object type for use by the createInputStreamInstance method. |
vendorName, version
Modifier | Constructor | Description |
---|---|---|
protected |
Constructs a blank ImageInputStreamSpi . |
|
Constructs an ImageInputStreamSpi with a given set of values. |
Modifier and Type | Method | Description |
---|---|---|
boolean |
canUseCacheFile() |
Returns true if the ImageInputStream implementation associated with this service provider can optionally make use of a cache file for improved performance and/or memory footrprint. |
ImageInputStream |
createInputStreamInstance |
Returns an instance of the ImageInputStream implementation associated with this service provider. |
abstract ImageInputStream |
createInputStreamInstance |
Returns an instance of the ImageInputStream implementation associated with this service provider. |
Class |
getInputClass() |
Returns a Class object representing the class or interface type that must be implemented by an input source in order to be "wrapped" in an ImageInputStream via the createInputStreamInstance method. |
boolean |
needsCacheFile() |
Returns true if the ImageInputStream implementation associated with this service provider requires the use of a cache File . |
getDescription, getVendorName, getVersion, onDeregistration, onRegistration
protected Class<?> inputClass
Class
object indicating the legal object type for use by the createInputStreamInstance
method.protected ImageInputStreamSpi()
ImageInputStreamSpi
. It is up to the subclass to initialize instance variables and/or override method implementations in order to provide working versions of all methods.public ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass)
ImageInputStreamSpi
with a given set of values.vendorName
- the vendor name.version
- a version identifier.inputClass
- a Class
object indicating the legal object type for use by the createInputStreamInstance
method.IllegalArgumentException
- if vendorName
is null
.IllegalArgumentException
- if version
is null
.public Class<?> getInputClass()
Class
object representing the class or interface type that must be implemented by an input source in order to be "wrapped" in an ImageInputStream
via the createInputStreamInstance
method. Typical return values might include InputStream.class
or URL.class
, but any class may be used.
Class
variable.public boolean canUseCacheFile()
true
if the ImageInputStream
implementation associated with this service provider can optionally make use of a cache file for improved performance and/or memory footrprint. If false
, the value of the useCache
argument to createInputStreamInstance
will be ignored. The default implementation returns false
.
true
if a cache file can be used by the input streams created by this service provider.public boolean needsCacheFile()
true
if the ImageInputStream
implementation associated with this service provider requires the use of a cache File
. If true
, the value of the useCache
argument to createInputStreamInstance
will be ignored. The default implementation returns false
.
true
if a cache file is needed by the input streams created by this service provider.public abstract ImageInputStream createInputStreamInstance(Object input, boolean useCache, File cacheDir) throws IOException
ImageInputStream
implementation associated with this service provider. If the use of a cache file is optional, the useCache
parameter will be consulted. Where a cache is required, or not applicable, the value of useCache
will be ignored.input
- an object of the class type returned by getInputClass
.useCache
- a boolean
indicating whether a cache file should be used, in cases where it is optional.cacheDir
- a File
indicating where the cache file should be created, or null
to use the system directory.ImageInputStream
instance.IllegalArgumentException
- if input
is not an instance of the correct class or is null
.IllegalArgumentException
- if a cache file is needed but cacheDir
is non-null
and is not a directory.IOException
- if a cache file is needed but cannot be created.public ImageInputStream createInputStreamInstance(Object input) throws IOException
ImageInputStream
implementation associated with this service provider. A cache file will be created in the system-dependent default temporary-file directory, if needed.input
- an object of the class type returned by getInputClass
.ImageInputStream
instance.IllegalArgumentException
- if input
is not an instance of the correct class or is null
.IOException
- if a cache file is needed but cannot be created.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/imageio/spi/ImageInputStreamSpi.html