Class ImageInputStreamSpi

java.lang.Object

javax.imageio.spi.IIOServiceProvider

javax.imageio.spi.ImageInputStreamSpi

All Implemented Interfaces:: RegisterableService

public abstract class ImageInputStreamSpi extends IIOServiceProvider

The service provider interface (SPI) for 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.

See Also:

Field Summary

Modifier and Type	Field	Description
`protected Class<?>`	`inputClass`	A `Class` object indicating the legal object type for use by the `createInputStreamInstance` method.

Fields declared in class IIOServiceProvider

vendorName, version

Modifier and Type	Field	Description
`protected String`	`vendorName`	A `String` to be returned from `getVendorName`, initially `null`.
`protected String`	`version`	A `String` to be returned from `getVersion`, initially null.

Constructor Summary

ImageInputStreamSpi()

ImageInputStreamSpi(String vendorName,
 String version,
 Class<?> inputClass)

Modifier	Constructor	Description
`protected`	Constructs a blank `ImageInputStreamSpi`.
	Constructs an `ImageInputStreamSpi` with a given set of values.

Method Summary

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(Object input)`	Returns an instance of the `ImageInputStream` implementation associated with this service provider.
`abstract ImageInputStream`	`createInputStreamInstance(Object input, boolean useCache, File cacheDir)`	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`.

Methods declared in class IIOServiceProvider

getDescription, getVendorName, getVersion, onDeregistration, onRegistration

Modifier and Type	Method	Description
`abstract String`	`getDescription(Locale locale)`	Returns a brief, human-readable description of this service provider and its associated implementation.
`String`	`getVendorName()`	Returns the name of the vendor responsible for creating this service provider and its associated implementation.
`String`	`getVersion()`	Returns a string describing the version number of this service provider and its associated implementation.
`void`	`onDeregistration(ServiceRegistry registry, Class<?> category)`	A callback that will be whenever the Spi class has been deregistered from a `ServiceRegistry`.
`void`	`onRegistration(ServiceRegistry registry, Class<?> category)`	A callback that will be called exactly once after the Spi class has been instantiated and registered in a `ServiceRegistry`.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Modifier and Type	Method	Description
`protected Object`	`clone()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this object.
`final void`	`notify()`	Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()`	Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()`	Returns a string representation of the object.
`final void`	`wait()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`final void`	`wait(long timeoutMillis)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis, int nanos)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Field Details

inputClass

protected Class<?> inputClass

A Class object indicating the legal object type for use by the createInputStreamInstance method.

Constructor Details

ImageInputStreamSpi

protected ImageInputStreamSpi()

Constructs a blank 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.

ImageInputStreamSpi

public ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass)

Constructs an ImageInputStreamSpi with a given set of values.

Parameters:: vendorName - the vendor name.; version - a version identifier.; inputClass - a Class object indicating the legal object type for use by the createInputStreamInstance method.
Throws:: IllegalArgumentException - if vendorName is null.; IllegalArgumentException - if version is null.

Method Details

getInputClass

public 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.

Typical return values might include InputStream.class or URL.class, but any class may be used.

Returns:

a Class variable.

See Also:

canUseCacheFile

public 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. If false, the value of the useCache argument to createInputStreamInstance 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()

Returns 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.

Returns:: true if a cache file is needed by the input streams created by this service provider.

createInputStreamInstance

public abstract ImageInputStream createInputStreamInstance(Object input, boolean useCache, File cacheDir) throws IOException

Returns an instance of the 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.

Parameters:

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.

Returns:

an ImageInputStream instance.

Throws:

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.

See Also:

createInputStreamInstance

public ImageInputStream createInputStreamInstance(Object input) throws IOException

Returns an instance of the ImageInputStream 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 by getInputClass.

Returns:

an ImageInputStream instance.

Throws:

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.

See Also:

© 1993, 2025, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.