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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.imageio.stream;
import java.io.*;
/**
* The FileCacheImageInputStream class is an implementation of ImageInputStream
* which reads from its InputStream and uses a temporary file as a cache.
*
* @since Android 1.0
*/
public class FileCacheImageInputStream extends ImageInputStreamImpl {
/**
* The is.
*/
private InputStream is;
/**
* The file.
*/
private File file;
/**
* The raf.
*/
private RandomAccessFile raf;
/**
* Instantiates a new FileCacheImageInputStream from the specified
* InputStream and using the specified File as its cache directory.
*
* @param stream
* the InputStream for reading.
* @param cacheDir
* the cache directory where the cache file will be created.
* @throws IOException
* if an I/O exception has occurred.
*/
public FileCacheImageInputStream(InputStream stream, File cacheDir) throws IOException {
if (stream == null) {
throw new IllegalArgumentException("stream == null!");
}
is = stream;
if (cacheDir == null || cacheDir.isDirectory()) {
file = File.createTempFile(FileCacheImageOutputStream.IIO_TEMP_FILE_PREFIX, null,
cacheDir);
file.deleteOnExit();
} else {
throw new IllegalArgumentException("Not a directory!");
}
raf = new RandomAccessFile(file, "rw");
}
@Override
public int read() throws IOException {
bitOffset = 0;
if (streamPos >= raf.length()) {
int b = is.read();
if (b < 0) {
return -1;
}
raf.seek(streamPos++);
raf.write(b);
return b;
}
raf.seek(streamPos++);
return raf.read();
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
bitOffset = 0;
if (streamPos >= raf.length()) {
int nBytes = is.read(b, off, len);
if (nBytes < 0) {
return -1;
}
raf.seek(streamPos);
raf.write(b, off, nBytes);
streamPos += nBytes;
return nBytes;
}
raf.seek(streamPos);
int nBytes = raf.read(b, off, len);
streamPos += nBytes;
return nBytes;
}
@Override
public boolean isCached() {
return true;
}
@Override
public boolean isCachedFile() {
return true;
}
@Override
public boolean isCachedMemory() {
return false;
}
@Override
public void close() throws IOException {
super.close();
raf.close();
file.delete();
}
}
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