1 /* 2 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.util.zip; 27 28 import java.io.FilterInputStream; 29 import java.io.InputStream; 30 import java.io.IOException; 31 32 /** 33 * Implements an input stream filter for compressing data in the "deflate" 34 * compression format. 35 * 36 * @since 1.6 37 * @author David R Tribble (david@tribble.com) 38 * 39 * @see DeflaterOutputStream 40 * @see InflaterOutputStream 41 * @see InflaterInputStream 42 */ 43 44 public class DeflaterInputStream extends FilterInputStream { 45 /** Compressor for this stream. */ 46 protected final Deflater def; 47 48 /** Input buffer for reading compressed data. */ 49 protected final byte[] buf; 50 51 /** Temporary read buffer. */ 52 private byte[] rbuf = new byte[1]; 53 54 /** Default compressor is used. */ 55 private boolean usesDefaultDeflater = false; 56 57 /** End of the underlying input stream has been reached. */ 58 private boolean reachEOF = false; 59 60 /** 61 * Check to make sure that this stream has not been closed. 62 */ 63 private void ensureOpen() throws IOException { 64 if (in == null) { 65 throw new IOException("Stream closed"); 66 } 67 } 68 69 /** 70 * Creates a new input stream with a default compressor and buffer 71 * size. 72 * 73 * @param in input stream to read the uncompressed data to 74 * @throws NullPointerException if {@code in} is null 75 */ 76 public DeflaterInputStream(InputStream in) { 77 this(in, new Deflater()); 78 usesDefaultDeflater = true; 79 } 80 81 /** 82 * Creates a new input stream with the specified compressor and a 83 * default buffer size. 84 * 85 * @param in input stream to read the uncompressed data to 86 * @param defl compressor ("deflater") for this stream 87 * @throws NullPointerException if {@code in} or {@code defl} is null 88 */ 89 public DeflaterInputStream(InputStream in, Deflater defl) { 90 this(in, defl, 512); 91 } 92 93 /** 94 * Creates a new input stream with the specified compressor and buffer 95 * size. 96 * 97 * @param in input stream to read the uncompressed data to 98 * @param defl compressor ("deflater") for this stream 99 * @param bufLen compression buffer size 100 * @throws IllegalArgumentException if {@code bufLen} is <= 0 101 * @throws NullPointerException if {@code in} or {@code defl} is null 102 */ 103 public DeflaterInputStream(InputStream in, Deflater defl, int bufLen) { 104 super(in); 105 106 // Sanity checks 107 if (in == null) 108 throw new NullPointerException("Null input"); 109 if (defl == null) 110 throw new NullPointerException("Null deflater"); 111 if (bufLen < 1) 112 throw new IllegalArgumentException("Buffer size < 1"); 113 114 // Initialize 115 def = defl; 116 buf = new byte[bufLen]; 117 } 118 119 /** 120 * Closes this input stream and its underlying input stream, discarding 121 * any pending uncompressed data. 122 * 123 * @throws IOException if an I/O error occurs 124 */ 125 public void close() throws IOException { 126 if (in != null) { 127 try { 128 // Clean up 129 if (usesDefaultDeflater) { 130 def.end(); 131 } 132 133 in.close(); 134 } finally { 135 in = null; 136 } 137 } 138 } 139 140 /** 141 * Reads a single byte of compressed data from the input stream. 142 * This method will block until some input can be read and compressed. 143 * 144 * @return a single byte of compressed data, or -1 if the end of the 145 * uncompressed input stream is reached 146 * @throws IOException if an I/O error occurs or if this stream is 147 * already closed 148 */ 149 public int read() throws IOException { 150 // Read a single byte of compressed data 151 int len = read(rbuf, 0, 1); 152 if (len <= 0) 153 return -1; 154 return (rbuf[0] & 0xFF); 155 } 156 157 /** 158 * Reads compressed data into a byte array. 159 * This method will block until some input can be read and compressed. 160 * 161 * @param b buffer into which the data is read 162 * @param off starting offset of the data within {@code b} 163 * @param len maximum number of compressed bytes to read into {@code b} 164 * @return the actual number of bytes read, or -1 if the end of the 165 * uncompressed input stream is reached 166 * @throws IndexOutOfBoundsException if {@code len} > {@code b.length - 167 * off} 168 * @throws IOException if an I/O error occurs or if this input stream is 169 * already closed 170 */ 171 public int read(byte[] b, int off, int len) throws IOException { 172 // Sanity checks 173 ensureOpen(); 174 if (b == null) { 175 throw new NullPointerException("Null buffer for read"); 176 } else if (off < 0 || len < 0 || len > b.length - off) { 177 throw new IndexOutOfBoundsException(); 178 } else if (len == 0) { 179 return 0; 180 } 181 182 // Read and compress (deflate) input data bytes 183 int cnt = 0; 184 while (len > 0 && !def.finished()) { 185 int n; 186 187 // Read data from the input stream 188 if (def.needsInput()) { 189 n = in.read(buf, 0, buf.length); 190 if (n < 0) { 191 // End of the input stream reached 192 def.finish(); 193 } else if (n > 0) { 194 def.setInput(buf, 0, n); 195 } 196 } 197 198 // Compress the input data, filling the read buffer 199 n = def.deflate(b, off, len); 200 cnt += n; 201 off += n; 202 len -= n; 203 } 204 if (cnt == 0 && def.finished()) { 205 reachEOF = true; 206 cnt = -1; 207 } 208 209 return cnt; 210 } 211 212 /** 213 * Skips over and discards data from the input stream. 214 * This method may block until the specified number of bytes are read and 215 * skipped. <em>Note:</em> While {@code n} is given as a {@code long}, 216 * the maximum number of bytes which can be skipped is 217 * {@code Integer.MAX_VALUE}. 218 * 219 * @param n number of bytes to be skipped 220 * @return the actual number of bytes skipped 221 * @throws IOException if an I/O error occurs or if this stream is 222 * already closed 223 */ 224 public long skip(long n) throws IOException { 225 if (n < 0) { 226 throw new IllegalArgumentException("negative skip length"); 227 } 228 ensureOpen(); 229 230 // Skip bytes by repeatedly decompressing small blocks 231 if (rbuf.length < 512) 232 rbuf = new byte[512]; 233 234 int total = (int)Math.min(n, Integer.MAX_VALUE); 235 long cnt = 0; 236 while (total > 0) { 237 // Read a small block of uncompressed bytes 238 int len = read(rbuf, 0, (total <= rbuf.length ? total : rbuf.length)); 239 240 if (len < 0) { 241 break; 242 } 243 cnt += len; 244 total -= len; 245 } 246 return cnt; 247 } 248 249 /** 250 * Returns 0 after EOF has been reached, otherwise always return 1. 251 * <p> 252 * Programs should not count on this method to return the actual number 253 * of bytes that could be read without blocking 254 * @return zero after the end of the underlying input stream has been 255 * reached, otherwise always returns 1 256 * @throws IOException if an I/O error occurs or if this stream is 257 * already closed 258 */ 259 public int available() throws IOException { 260 ensureOpen(); 261 if (reachEOF) { 262 return 0; 263 } 264 return 1; 265 } 266 267 /** 268 * Always returns {@code false} because this input stream does not support 269 * the {@link #mark mark()} and {@link #reset reset()} methods. 270 * 271 * @return false, always 272 */ 273 public boolean markSupported() { 274 return false; 275 } 276 277 /** 278 * <i>This operation is not supported</i>. 279 * 280 * @param limit maximum bytes that can be read before invalidating the position marker 281 */ 282 public void mark(int limit) { 283 // Operation not supported 284 } 285 286 /** 287 * <i>This operation is not supported</i>. 288 * 289 * @throws IOException always thrown 290 */ 291 public void reset() throws IOException { 292 throw new IOException("mark/reset not supported"); 293 } 294 }