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