| /* |
| * Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| 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}s. For more information on service |
| * provider interfaces, see the class comment for the |
| * {@code IIORegistry} class. |
| * |
| * <p> This interface allows arbitrary objects to be "wrapped" by |
| * instances of {@code ImageInputStream}. For example, |
| * a particular {@code ImageInputStreamSpi} might allow |
| * a generic {@code InputStream} to be used as an input source; |
| * another might take input from a {@code URL}. |
| * |
| * <p> By treating the creation of {@code ImageInputStream}s as a |
| * pluggable service, it becomes possible to handle future input |
| * sources without changing the API. Also, high-performance |
| * implementations of {@code ImageInputStream} (for example, |
| * native implementations for a particular platform) can be installed |
| * and used transparently by applications. |
| * |
| * @see IIORegistry |
| * @see javax.imageio.stream.ImageInputStream |
| * |
| */ |
| public abstract class ImageInputStreamSpi extends IIOServiceProvider { |
| |
| /** |
| * A {@code Class} object indicating the legal object type |
| * for use by the {@code createInputStreamInstance} method. |
| */ |
| protected Class<?> inputClass; |
| |
| /** |
| * Constructs a blank {@code 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. |
| */ |
| protected ImageInputStreamSpi() { |
| } |
| |
| /** |
| * Constructs an {@code ImageInputStreamSpi} with a given set |
| * of values. |
| * |
| * @param vendorName the vendor name. |
| * @param version a version identifier. |
| * @param inputClass a {@code Class} object indicating the |
| * legal object type for use by the |
| * {@code createInputStreamInstance} method. |
| * |
| * @exception IllegalArgumentException if {@code vendorName} |
| * is {@code null}. |
| * @exception IllegalArgumentException if {@code version} |
| * is {@code null}. |
| */ |
| public ImageInputStreamSpi(String vendorName, |
| String version, |
| Class<?> inputClass) { |
| super(vendorName, version); |
| this.inputClass = inputClass; |
| } |
| |
| /** |
| * Returns a {@code Class} object representing the class or |
| * interface type that must be implemented by an input source in |
| * order to be "wrapped" in an {@code ImageInputStream} via |
| * the {@code createInputStreamInstance} method. |
| * |
| * <p> Typical return values might include |
| * {@code InputStream.class} or {@code URL.class}, but |
| * any class may be used. |
| * |
| * @return a {@code Class} variable. |
| * |
| * @see #createInputStreamInstance(Object, boolean, File) |
| */ |
| public Class<?> getInputClass() { |
| return inputClass; |
| } |
| |
| /** |
| * Returns {@code true} if the {@code ImageInputStream} |
| * implementation associated with this service provider can |
| * optionally make use of a cache file for improved performance |
| * and/or memory footrprint. If {@code false}, the value of |
| * the {@code useCache} argument to |
| * {@code createInputStreamInstance} will be ignored. |
| * |
| * <p> The default implementation returns {@code false}. |
| * |
| * @return {@code true} if a cache file can be used by the |
| * input streams created by this service provider. |
| */ |
| public boolean canUseCacheFile() { |
| return false; |
| } |
| |
| /** |
| * Returns {@code true} if the {@code ImageInputStream} |
| * implementation associated with this service provider requires |
| * the use of a cache {@code File}. If {@code true}, |
| * the value of the {@code useCache} argument to |
| * {@code createInputStreamInstance} will be ignored. |
| * |
| * <p> The default implementation returns {@code false}. |
| * |
| * @return {@code true} 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} |
| * implementation associated with this service provider. If the |
| * use of a cache file is optional, the {@code useCache} |
| * parameter will be consulted. Where a cache is required, or |
| * not applicable, the value of {@code useCache} will be ignored. |
| * |
| * @param input an object of the class type returned by |
| * {@code getInputClass}. |
| * @param useCache a {@code boolean} indicating whether a |
| * cache file should be used, in cases where it is optional. |
| * @param cacheDir a {@code File} indicating where the |
| * cache file should be created, or {@code null} to use the |
| * system directory. |
| * |
| * @return an {@code ImageInputStream} instance. |
| * |
| * @exception IllegalArgumentException if {@code input} is |
| * not an instance of the correct class or is {@code null}. |
| * @exception IllegalArgumentException if a cache file is needed |
| * but {@code cacheDir} is non-{@code null} 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} |
| * 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}. |
| * |
| * @return an {@code ImageInputStream} instance. |
| * |
| * @exception IllegalArgumentException if {@code input} is |
| * not an instance of the correct class or is {@code null}. |
| * @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); |
| } |
| } |