- /*
- * @(#)ImageInputStreamSpi.java 1.21 03/01/23
- *
- * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
-
- package javax.imageio.spi;
-
- import java.io.File;
- import java.io.IOException;
- import javax.imageio.stream.ImageInputStream;
-
- /**
- * The service provider interface (SPI) for
- * <code>ImageInputStream</code>s. For more information on service
- * provider interfaces, see the class comment for the
- * <code>IIORegistry</code> class.
- *
- * <p> This interface allows arbitrary objects to be "wrapped" by
- * instances of <code>ImageInputStream</code>. For example,
- * a particular <code>ImageInputStreamSpi</code> might allow
- * a generic <code>InputStream</code> to be used as an input source;
- * another might take input from a <code>URL</code>.
- *
- * <p> By treating the creation of <code>ImageInputStream</code>s as a
- * pluggable service, it becomes possible to handle future input
- * sources without changing the API. Also, high-performance
- * implementations of <code>ImageInputStream</code> (for example,
- * native implementations for a particular platform) can be installed
- * and used transparently by applications.
- *
- * @see IIORegistry
- * @see javax.imageio.stream.ImageInputStream
- *
- * @version 0.5
- */
- public abstract class ImageInputStreamSpi extends IIOServiceProvider {
-
- /**
- * A <code>Class</code> object indicating the legal object type
- * for use by the <code>createInputStreamInstance</code> method.
- */
- protected Class inputClass;
-
- /**
- * Constructs a blank <code>ImageInputStreamSpi</code>. It is up
- * to the subclass to initialize instance variables and/or
- * override method implementations in order to provide working
- * versions of all methods.
- */
- protected ImageInputStreamSpi() {
- }
-
- /**
- * Constructs an <code>ImageInputStreamSpi</code> with a given set
- * of values.
- *
- * @param vendorName the vendor name.
- * @param version a version identifier.
- * @param inputClass a <code>Class</code> object indicating the
- * legal object type for use by the
- * <code>createInputStreamInstance</code> method.
- *
- * @exception IllegalArgumentException if <code>vendorName</code>
- * is <code>null</code>.
- * @exception IllegalArgumentException if <code>version</code>
- * is <code>null</code>.
- */
- public ImageInputStreamSpi(String vendorName,
- String version,
- Class inputClass) {
- super(vendorName, version);
- this.inputClass = inputClass;
- }
-
- /**
- * Returns a <code>Class</code> object representing the class or
- * interface type that must be implemented by an input source in
- * order to be "wrapped" in an <code>ImageInputStream</code> via
- * the <code>createInputStreamInstance</code> method.
- *
- * <p> Typical return values might include
- * <code>InputStream.class</code> or <code>URL.class</code>, but
- * any class may be used.
- *
- * @return a <code>Class</code> variable.
- *
- * @see #createInputStreamInstance(Object, boolean, File)
- */
- public Class getInputClass() {
- return inputClass;
- }
-
- /**
- * Returns <code>true</code> if the <code>ImageInputStream</code>
- * implementation associated with this service provider can
- * optionally make use of a cache file for improved performance
- * and/or memory footrprint. If <code>false</code>, the value of
- * the <code>useCache</code> argument to
- * <code>createInputStreamInstance</code> will be ignored.
- *
- * <p> The default implementation returns <code>false</code>.
- *
- * @return <code>true</code> if a cache file can be used by the
- * input streams created by this service provider.
- */
- public boolean canUseCacheFile() {
- return false;
- }
-
- /**
- * Returns <code>true</code> if the <code>ImageInputStream</code>
- * implementation associated with this service provider requires
- * the use of a cache <code>File</code>. If <code>true</code>,
- * the value of the <code>useCache</code> argument to
- * <code>createInputStreamInstance</code> will be ignored.
- *
- * <p> The default implementation returns <code>false</code>.
- *
- * @return <code>true</code> if a cache file is needed by the
- * input streams created by this service provider.
- */
- public boolean needsCacheFile() {
- return false;
- }
-
- /**
- * Returns an instance of the <code>ImageInputStream</code>
- * implementation associated with this service provider. If the
- * use of a cache file is optional, the <code>useCache</code>
- * parameter will be consulted. Where a cache is required, or
- * not applicable, the value of <code>useCache</code> will be ignored.
- *
- * @param input an object of the class type returned by
- * <code>getInputClass</code>.
- * @param useCache a <code>boolean</code> indicating whether a
- * cache file should be used, in cases where it is optional.
- * @param cacheDir a <code>File</code> indicating where the
- * cache file should be created, or <code>null</code> to use the
- * system directory.
- *
- * @return an <code>ImageInputStream</code> instance.
- *
- * @exception IllegalArgumentException if <code>input</code> is
- * not an instance of the correct class or is <code>null</code>.
- * @exception IllegalArgumentException if a cache file is needed
- * but <code>cacheDir</code> is non-<code>null</code> and is not a
- * directory.
- * @exception IOException if a cache file is needed but cannot be
- * created.
- *
- * @see #getInputClass
- * @see #canUseCacheFile
- * @see #needsCacheFile
- */
- public abstract ImageInputStream
- createInputStreamInstance(Object input,
- boolean useCache,
- File cacheDir) throws IOException;
-
- /**
- * Returns an instance of the <code>ImageInputStream</code>
- * implementation associated with this service provider. A cache
- * file will be created in the system-dependent default
- * temporary-file directory, if needed.
- *
- * @param input an object of the class type returned by
- * <code>getInputClass</code>.
- *
- * @return an <code>ImageInputStream</code> instance.
- *
- * @exception IllegalArgumentException if <code>input</code> is
- * not an instance of the correct class or is <code>null</code>.
- * @exception IOException if a cache file is needed but cannot be
- * created.
- *
- * @see #getInputClass()
- */
- public ImageInputStream createInputStreamInstance(Object input)
- throws IOException {
- return createInputStreamInstance(input, true, null);
- }
- }