public abstract class

ImageInputStreamSpi

extends IIOServiceProvider
java.lang.Object
   ↳ javax.imageio.spi.IIOServiceProvider
     ↳ javax.imageio.spi.ImageInputStreamSpi
Known Direct Subclasses

Class Overview

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

Summary

Fields
protected Class<?> inputClass A Class object indicating the legal object type for use by the createInputStreamInstance method.
[Expand]
Inherited Fields
From class javax.imageio.spi.IIOServiceProvider
Public Constructors
ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass)
Constructs an ImageInputStreamSpi with a given set of values.
Protected Constructors
ImageInputStreamSpi()
Constructs a blank ImageInputStreamSpi.
Public Methods
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.
abstract ImageInputStream createInputStreamInstance(Object input, boolean useCache, File cacheDir)
Returns an instance of the ImageInputStream implementation associated with this service provider.
ImageInputStream createInputStreamInstance(Object input)
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.
[Expand]
Inherited Methods
From class javax.imageio.spi.IIOServiceProvider
From class java.lang.Object
From interface javax.imageio.spi.RegisterableService

Fields

protected Class<?> inputClass

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

Public Constructors

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.

Protected Constructors

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.

Public Methods

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.

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

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

public ImageInputStream createInputStreamInstance (Object input)

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

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

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.