Class IIORegistry

java.lang.Object

javax.imageio.spi.ServiceRegistry

javax.imageio.spi.IIORegistry

public final class IIORegistry extends ServiceRegistry

A registry for Image I/O service provider instances. Service provider classes may be discovered at runtime by the mechanisms documented in ServiceLoader. The intent is that it be relatively inexpensive to load and inspect all available Image I/O service provider classes. These classes may then be used to locate and instantiate more heavyweight classes that will perform actual work, in this case instances of ImageReader, ImageWriter, ImageTranscoder, ImageInputStream, and ImageOutputStream. Service providers included in the Java runtime are automatically loaded as soon as this class is instantiated.

When the registerApplicationClasspathSpis method is called, additional service provider instances will be discovered using ServiceLoader.

It is also possible to manually add service providers not found automatically, as well as to remove those that are using the interfaces of the ServiceRegistry class. Thus the application may customize the contents of the registry as it sees fit.

For information on how to create and deploy service providers, refer to the documentation on ServiceLoader

Nested Class Summary

Nested classes/interfaces declared in class ServiceRegistry

ServiceRegistry.Filter

Modifier and Type	Class	Description
`static interface`	`ServiceRegistry.Filter`	A simple filter interface used by `ServiceRegistry.getServiceProviders` to select providers matching an arbitrary criterion.

Method Summary

Modifier and Type	Method	Description
`static IIORegistry`	`getDefaultInstance()`	Returns the default `IIORegistry` instance used by the Image I/O API.
`void`	`registerApplicationClasspathSpis()`	Registers all available service providers found on the application class path, using the default `ClassLoader`.

Methods declared in class ServiceRegistry

contains, deregisterAll, deregisterAll, deregisterServiceProvider, deregisterServiceProvider, getCategories, getServiceProviderByClass, getServiceProviders, getServiceProviders, lookupProviders, lookupProviders, registerServiceProvider, registerServiceProvider, registerServiceProviders, setOrdering, unsetOrdering

Modifier and Type	Method	Description
`boolean`	`contains(Object provider)`	Returns `true` if `provider` is currently registered.
`void`	`deregisterAll()`	Deregisters all currently registered service providers from all categories.
`void`	`deregisterAll(Class<?> category)`	Deregisters all service provider object currently registered under the given category.
`void`	`deregisterServiceProvider(Object provider)`	Removes a service provider object from all categories that contain it.
`<T> boolean`	`deregisterServiceProvider(T provider, Class<T> category)`	Removes a service provider object from the given category.
`Iterator<Class<?>>`	`getCategories()`	Returns an `Iterator` of `Class` objects indicating the current set of categories.
`<T> T`	`getServiceProviderByClass(Class<T> providerClass)`	Returns the currently registered service provider object that is of the given class type.
`<T> Iterator<T>`	`getServiceProviders(Class<T> category, boolean useOrdering)`	Returns an `Iterator` containing all registered service providers in the given category.
`<T> Iterator<T>`	`getServiceProviders(Class<T> category, ServiceRegistry.Filter filter, boolean useOrdering)`	Returns an `Iterator` containing service provider objects within a given category that satisfy a criterion imposed by the supplied `ServiceRegistry.Filter` object's `filter` method.
`static <T> Iterator<T>`	`lookupProviders(Class<T> providerClass)`	Locates and incrementally instantiates the available providers of a given service using the context class loader.
`static <T> Iterator<T>`	`lookupProviders(Class<T> providerClass, ClassLoader loader)`	Searches for implementations of a particular service class using the given class loader.
`void`	`registerServiceProvider(Object provider)`	Adds a service provider object to the registry.
`<T> boolean`	`registerServiceProvider(T provider, Class<T> category)`	Adds a service provider object to the registry.
`void`	`registerServiceProviders(Iterator<?> providers)`	Adds a set of service provider objects, taken from an `Iterator` to the registry.
`<T> boolean`	`setOrdering(Class<T> category, T firstProvider, T secondProvider)`	Sets a pairwise ordering between two service provider objects within a given category.
`<T> boolean`	`unsetOrdering(Class<T> category, T firstProvider, T secondProvider)`	Sets a pairwise ordering between two service provider objects within a given category.

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.

Method Details

getDefaultInstance

public static IIORegistry getDefaultInstance()

Returns the default IIORegistry instance used by the Image I/O API. This instance should be used for all registry functions.

Returns:: the default registry for the Image I/O API

registerApplicationClasspathSpis

public void registerApplicationClasspathSpis()

Registers all available service providers found on the application class path, using the default ClassLoader. This method is typically invoked by the ImageIO.scanForPlugins method.

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.