1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package javax.imageio.stream; 19 20 import java.io.*; 21 22 /** 23 * The FileCacheImageInputStream class is an implementation of ImageInputStream 24 * which reads from its InputStream and uses a temporary file as a cache. 25 * 26 * @since Android 1.0 27 */ 28 public class FileCacheImageInputStream extends ImageInputStreamImpl { 29 30 /** 31 * The is. 32 */ 33 private InputStream is; 34 35 /** 36 * The file. 37 */ 38 private File file; 39 40 /** 41 * The raf. 42 */ 43 private RandomAccessFile raf; 44 45 /** 46 * Instantiates a new FileCacheImageInputStream from the specified 47 * InputStream and using the specified File as its cache directory. 48 * 49 * @param stream 50 * the InputStream for reading. 51 * @param cacheDir 52 * the cache directory where the cache file will be created. 53 * @throws IOException 54 * if an I/O exception has occurred. 55 */ FileCacheImageInputStream(InputStream stream, File cacheDir)56 public FileCacheImageInputStream(InputStream stream, File cacheDir) throws IOException { 57 if (stream == null) { 58 throw new IllegalArgumentException("stream == null!"); 59 } 60 is = stream; 61 62 if (cacheDir == null || cacheDir.isDirectory()) { 63 file = File.createTempFile(FileCacheImageOutputStream.IIO_TEMP_FILE_PREFIX, null, 64 cacheDir); 65 file.deleteOnExit(); 66 } else { 67 throw new IllegalArgumentException("Not a directory!"); 68 } 69 70 raf = new RandomAccessFile(file, "rw"); 71 } 72 73 @Override read()74 public int read() throws IOException { 75 bitOffset = 0; 76 77 if (streamPos >= raf.length()) { 78 int b = is.read(); 79 80 if (b < 0) { 81 return -1; 82 } 83 84 raf.seek(streamPos++); 85 raf.write(b); 86 return b; 87 } 88 89 raf.seek(streamPos++); 90 return raf.read(); 91 } 92 93 @Override read(byte[] b, int off, int len)94 public int read(byte[] b, int off, int len) throws IOException { 95 bitOffset = 0; 96 97 if (streamPos >= raf.length()) { 98 int nBytes = is.read(b, off, len); 99 100 if (nBytes < 0) { 101 return -1; 102 } 103 104 raf.seek(streamPos); 105 raf.write(b, off, nBytes); 106 streamPos += nBytes; 107 return nBytes; 108 } 109 110 raf.seek(streamPos); 111 int nBytes = raf.read(b, off, len); 112 streamPos += nBytes; 113 return nBytes; 114 } 115 116 @Override isCached()117 public boolean isCached() { 118 return true; 119 } 120 121 @Override isCachedFile()122 public boolean isCachedFile() { 123 return true; 124 } 125 126 @Override isCachedMemory()127 public boolean isCachedMemory() { 128 return false; 129 } 130 131 @Override close()132 public void close() throws IOException { 133 super.close(); 134 raf.close(); 135 file.delete(); 136 } 137 } 138