/*
* Copyright 2000-2007 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package ae.javax.imageio.stream;
import java.io.InputStream;
import java.io.IOException;
import ae.com.sun.imageio.stream.StreamFinalizer;
import ae.sun.java2d.Disposer;
import ae.sun.java2d.DisposerRecord;
/**
* An implementation of <code>ImageInputStream</code> that gets its
* input from a regular <code>InputStream</code>. 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</code> when reading from a regular
* <code>InputStream</code>. 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</code> that will read
* from a given <code>InputStream</code>.
*
* @param stream an <code>InputStream</code> to read from.
*
* @exception IllegalArgumentException if <code>stream</code> is
* <code>null</code>.
*/
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</code> since this
* <code>ImageInputStream</code> caches data in order to allow
* seeking backwards.
*
* @return <code>true</code>.
*
* @see #isCachedMemory
* @see #isCachedFile
*/
public boolean isCached() {
return true;
}
/**
* Returns <code>false</code> since this
* <code>ImageInputStream</code> does not maintain a file cache.
*
* @return <code>false</code>.
*
* @see #isCached
* @see #isCachedMemory
*/
public boolean isCachedFile() {
return false;
}
/**
* Returns <code>true</code> since this
* <code>ImageInputStream</code> maintains a main memory cache.
*
* @return <code>true</code>.
*
* @see #isCached
* @see #isCachedFile
*/
public boolean isCachedMemory() {
return true;
}
/**
* Closes this <code>MemoryCacheImageInputStream</code>, freeing
* the cache. The source <code>InputStream</code> is not closed.
*/
public void close() throws IOException {
super.close();
disposerRecord.dispose(); // this resets the MemoryCache
stream = null;
cache = null;
}
/**
* {@inheritDoc}
*/
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;
}
}
}
}