| /* |
| * Copyright (c) 2000, 2017, 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.stream; |
| |
| import java.io.InputStream; |
| import java.io.IOException; |
| import com.sun.imageio.stream.StreamFinalizer; |
| import sun.java2d.Disposer; |
| import sun.java2d.DisposerRecord; |
| |
| /** |
| * An implementation of {@code ImageInputStream} that gets its |
| * input from a regular {@code InputStream}. A memory buffer is |
| * used to cache at least the data between the discard position and |
| * the current read position. |
| * |
| * <p> In general, it is preferable to use a |
| * {@code FileCacheImageInputStream} when reading from a regular |
| * {@code InputStream}. This class is provided for cases where |
| * it is not possible to create a writable temporary file. |
| * |
| */ |
| public class MemoryCacheImageInputStream extends ImageInputStreamImpl { |
| |
| private InputStream stream; |
| |
| private MemoryCache cache = new MemoryCache(); |
| |
| /** The referent to be registered with the Disposer. */ |
| private final Object disposerReferent; |
| |
| /** The DisposerRecord that resets the underlying MemoryCache. */ |
| private final DisposerRecord disposerRecord; |
| |
| /** |
| * Constructs a {@code MemoryCacheImageInputStream} that will read |
| * from a given {@code InputStream}. |
| * |
| * @param stream an {@code InputStream} to read from. |
| * |
| * @exception IllegalArgumentException if {@code stream} is |
| * {@code null}. |
| */ |
| public MemoryCacheImageInputStream(InputStream stream) { |
| if (stream == null) { |
| throw new IllegalArgumentException("stream == null!"); |
| } |
| this.stream = stream; |
| |
| disposerRecord = new StreamDisposerRecord(cache); |
| if (getClass() == MemoryCacheImageInputStream.class) { |
| disposerReferent = new Object(); |
| Disposer.addRecord(disposerReferent, disposerRecord); |
| } else { |
| disposerReferent = new StreamFinalizer(this); |
| } |
| } |
| |
| public int read() throws IOException { |
| checkClosed(); |
| bitOffset = 0; |
| long pos = cache.loadFromStream(stream, streamPos+1); |
| if (pos >= streamPos+1) { |
| return cache.read(streamPos++); |
| } else { |
| return -1; |
| } |
| } |
| |
| public int read(byte[] b, int off, int len) throws IOException { |
| checkClosed(); |
| |
| if (b == null) { |
| throw new NullPointerException("b == null!"); |
| } |
| if (off < 0 || len < 0 || off + len > b.length || off + len < 0) { |
| throw new IndexOutOfBoundsException |
| ("off < 0 || len < 0 || off+len > b.length || off+len < 0!"); |
| } |
| |
| bitOffset = 0; |
| |
| if (len == 0) { |
| return 0; |
| } |
| |
| long pos = cache.loadFromStream(stream, streamPos+len); |
| |
| len = (int)(pos - streamPos); // In case stream ended early |
| |
| if (len > 0) { |
| cache.read(b, off, len, streamPos); |
| streamPos += len; |
| return len; |
| } else { |
| return -1; |
| } |
| } |
| |
| public void flushBefore(long pos) throws IOException { |
| super.flushBefore(pos); // this will call checkClosed() for us |
| cache.disposeBefore(pos); |
| } |
| |
| /** |
| * Returns {@code true} since this |
| * {@code ImageInputStream} caches data in order to allow |
| * seeking backwards. |
| * |
| * @return {@code true}. |
| * |
| * @see #isCachedMemory |
| * @see #isCachedFile |
| */ |
| public boolean isCached() { |
| return true; |
| } |
| |
| /** |
| * Returns {@code false} since this |
| * {@code ImageInputStream} does not maintain a file cache. |
| * |
| * @return {@code false}. |
| * |
| * @see #isCached |
| * @see #isCachedMemory |
| */ |
| public boolean isCachedFile() { |
| return false; |
| } |
| |
| /** |
| * Returns {@code true} since this |
| * {@code ImageInputStream} maintains a main memory cache. |
| * |
| * @return {@code true}. |
| * |
| * @see #isCached |
| * @see #isCachedFile |
| */ |
| public boolean isCachedMemory() { |
| return true; |
| } |
| |
| /** |
| * Closes this {@code MemoryCacheImageInputStream}, freeing |
| * the cache. The source {@code InputStream} is not closed. |
| */ |
| public void close() throws IOException { |
| super.close(); |
| disposerRecord.dispose(); // this resets the MemoryCache |
| stream = null; |
| cache = null; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @deprecated The {@code finalize} method has been deprecated. |
| * Subclasses that override {@code finalize} in order to perform cleanup |
| * should be modified to use alternative cleanup mechanisms and |
| * to remove the overriding {@code finalize} method. |
| * When overriding the {@code finalize} method, its implementation must explicitly |
| * ensure that {@code super.finalize()} is invoked as described in {@link Object#finalize}. |
| * See the specification for {@link Object#finalize()} for further |
| * information about migration options. |
| */ |
| @Deprecated(since="9") |
| protected void finalize() throws Throwable { |
| // Empty finalizer: for performance reasons we instead use the |
| // Disposer mechanism for ensuring that the underlying |
| // MemoryCache is reset prior to garbage collection |
| } |
| |
| private static class StreamDisposerRecord implements DisposerRecord { |
| private MemoryCache cache; |
| |
| public StreamDisposerRecord(MemoryCache cache) { |
| this.cache = cache; |
| } |
| |
| public synchronized void dispose() { |
| if (cache != null) { |
| cache.reset(); |
| cache = null; |
| } |
| } |
| } |
| } |