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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.IOException;
import java.io.File;
import java.io.OutputStream;
import java.io.RandomAccessFile;
/**
* The FileCacheImageOutputStream class is an implementation of
* ImageOutputStream that writes to its OutputStream using a temporary file as a
* cache.
*
* @since Android 1.0
*/
public class FileCacheImageOutputStream extends ImageOutputStreamImpl {
/**
* The Constant IIO_TEMP_FILE_PREFIX.
*/
static final String IIO_TEMP_FILE_PREFIX = "iioCache";
/**
* The Constant MAX_BUFFER_LEN.
*/
static final int MAX_BUFFER_LEN = 1048575; // 1 MB - is it not too much?
/**
* The os.
*/
private OutputStream os;
/**
* The file.
*/
private File file;
/**
* The raf.
*/
private RandomAccessFile raf;
/**
* Instantiates a FileCacheImageOutputStream.
*
* @param stream
* the OutputStream for writing.
* @param cacheDir
* the cache directory where the cache file will be created.
* @throws IOException
* if an I/O exception has occurred.
*/
public FileCacheImageOutputStream(OutputStream stream, File cacheDir) throws IOException {
if (stream == null) {
throw new IllegalArgumentException("stream == null!");
}
os = stream;
if (cacheDir == null || cacheDir.isDirectory()) {
file = File.createTempFile(IIO_TEMP_FILE_PREFIX, null, cacheDir);
file.deleteOnExit();
} else {
throw new IllegalArgumentException("Not a directory!");
}
raf = new RandomAccessFile(file, "rw");
}
@Override
public void close() throws IOException {
flushBefore(raf.length());
super.close();
raf.close();
file.delete();
}
@Override
public boolean isCached() {
return true;
}
@Override
public boolean isCachedFile() {
return true;
}
@Override
public boolean isCachedMemory() {
return false;
}
@Override
public void write(int b) throws IOException {
flushBits(); // See the flushBits method description
raf.write(b);
streamPos++;
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
flushBits(); // See the flushBits method description
raf.write(b, off, len);
streamPos += len;
}
@Override
public int read() throws IOException {
bitOffset = 0; // Should reset
int res = raf.read();
if (res >= 0) {
streamPos++;
}
return res;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
bitOffset = 0;
int numRead = raf.read(b, off, len);
if (numRead > 0) {
streamPos += numRead;
}
return numRead;
}
@Override
public void flushBefore(long pos) throws IOException {
long readFromPos = flushedPos;
super.flushBefore(pos);
long bytesToRead = pos - readFromPos;
raf.seek(readFromPos);
if (bytesToRead < MAX_BUFFER_LEN) {
byte buffer[] = new byte[(int)bytesToRead];
raf.readFully(buffer);
os.write(buffer);
} else {
byte buffer[] = new byte[MAX_BUFFER_LEN];
while (bytesToRead > 0) {
int count = (int)Math.min(MAX_BUFFER_LEN, bytesToRead);
raf.readFully(buffer, 0, count);
os.write(buffer, 0, count);
bytesToRead -= count;
}
}
os.flush();
if (pos != streamPos) {
raf.seek(streamPos); // Reset the position
}
}
@Override
public void seek(long pos) throws IOException {
if (pos < flushedPos) {
throw new IndexOutOfBoundsException();
}
raf.seek(pos);
streamPos = raf.getFilePointer();
bitOffset = 0;
}
@Override
public long length() {
try {
return raf.length();
} catch (IOException e) {
return -1L;
}
}
}
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