| 1 | package be.nikiroo.utils; |
| 2 | |
| 3 | import java.io.IOException; |
| 4 | import java.io.InputStream; |
| 5 | import java.util.Arrays; |
| 6 | |
| 7 | /** |
| 8 | * This {@link InputStream} can be separated into sub-streams (you can process |
| 9 | * it as a normal {@link InputStream} but, when it is spent, you can call |
| 10 | * {@link NextableInputStream#next()} on it to unlock new data). |
| 11 | * <p> |
| 12 | * The separation in sub-streams is done via {@link NextableInputStreamStep}. |
| 13 | * |
| 14 | * @author niki |
| 15 | */ |
| 16 | public class NextableInputStream extends InputStream { |
| 17 | private NextableInputStreamStep step; |
| 18 | private boolean started; |
| 19 | private boolean stopped; |
| 20 | private boolean closed; |
| 21 | |
| 22 | private InputStream in; |
| 23 | private int openCounter; |
| 24 | private boolean eof; |
| 25 | private int pos; |
| 26 | private int len; |
| 27 | private byte[] buffer; |
| 28 | |
| 29 | // special use, prefetched next buffer |
| 30 | private byte[] buffer2; |
| 31 | private int pos2; |
| 32 | private int len2; |
| 33 | private byte[] originalBuffer; |
| 34 | |
| 35 | private long bytesRead; |
| 36 | |
| 37 | /** |
| 38 | * Create a new {@link NextableInputStream} that wraps the given |
| 39 | * {@link InputStream}. |
| 40 | * |
| 41 | * @param in |
| 42 | * the {@link InputStream} to wrap |
| 43 | * @param step |
| 44 | * how to separate it into sub-streams (can be NULL, but in that |
| 45 | * case it will behave as a normal {@link InputStream}) |
| 46 | */ |
| 47 | public NextableInputStream(InputStream in, NextableInputStreamStep step) { |
| 48 | this.in = in; |
| 49 | this.step = step; |
| 50 | |
| 51 | this.buffer = new byte[4096]; |
| 52 | this.originalBuffer = this.buffer; |
| 53 | this.pos = 0; |
| 54 | this.len = 0; |
| 55 | } |
| 56 | |
| 57 | /** |
| 58 | * Create a new {@link NextableInputStream} that wraps the given bytes array |
| 59 | * as a data source. |
| 60 | * |
| 61 | * @param in |
| 62 | * the array to wrap, cannot be NULL |
| 63 | * @param step |
| 64 | * how to separate it into sub-streams (can be NULL, but in that |
| 65 | * case it will behave as a normal {@link InputStream}) |
| 66 | */ |
| 67 | public NextableInputStream(byte[] in, NextableInputStreamStep step) { |
| 68 | this(in, step, 0, in.length); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Create a new {@link NextableInputStream} that wraps the given bytes array |
| 73 | * as a data source. |
| 74 | * |
| 75 | * @param in |
| 76 | * the array to wrap, cannot be NULL |
| 77 | * @param step |
| 78 | * how to separate it into sub-streams (can be NULL, but in that |
| 79 | * case it will behave as a normal {@link InputStream}) |
| 80 | * @param offset |
| 81 | * the offset to start the reading at |
| 82 | * @param length |
| 83 | * the number of bytes to take into account in the array, |
| 84 | * starting from the offset |
| 85 | * |
| 86 | * @throws NullPointerException |
| 87 | * if the array is NULL |
| 88 | * @throws IndexOutOfBoundsException |
| 89 | * if the offset and length do not correspond to the given array |
| 90 | */ |
| 91 | public NextableInputStream(byte[] in, NextableInputStreamStep step, |
| 92 | int offset, int length) { |
| 93 | if (in == null) { |
| 94 | throw new NullPointerException(); |
| 95 | } else if (offset < 0 || length < 0 || length > in.length - offset) { |
| 96 | throw new IndexOutOfBoundsException(); |
| 97 | } |
| 98 | |
| 99 | this.in = null; |
| 100 | this.step = step; |
| 101 | |
| 102 | this.buffer = in; |
| 103 | this.originalBuffer = this.buffer; |
| 104 | this.pos = offset; |
| 105 | this.len = length; |
| 106 | |
| 107 | checkBuffer(true); |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Return this very same {@link NextableInputStream}, but keep a counter of |
| 112 | * how many streams were open this way. When calling |
| 113 | * {@link NextableInputStream#close()}, decrease this counter if it is not |
| 114 | * already zero instead of actually closing the stream. |
| 115 | * <p> |
| 116 | * You are now responsible for it — you <b>must</b> close it. |
| 117 | * <p> |
| 118 | * This method allows you to use a wrapping stream around this one and still |
| 119 | * close the wrapping stream. |
| 120 | * |
| 121 | * @return the same stream, but you are now responsible for closing it |
| 122 | * |
| 123 | * @throws IOException |
| 124 | * in case of I/O error or if the stream is closed |
| 125 | */ |
| 126 | public synchronized InputStream open() throws IOException { |
| 127 | checkClose(); |
| 128 | openCounter++; |
| 129 | return this; |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * Unblock the processing of the next sub-stream. |
| 134 | * <p> |
| 135 | * It can only be called when the "current" stream is spent (i.e., you must |
| 136 | * first process the stream until it is spent). |
| 137 | * <p> |
| 138 | * We consider that when the under-laying {@link InputStream} is also spent, |
| 139 | * we cannot have a next sub-stream (it will thus return FALSE). |
| 140 | * <p> |
| 141 | * {@link IOException}s can happen when we have no data available in the |
| 142 | * buffer; in that case, we fetch more data to know if we can have a next |
| 143 | * sub-stream or not. |
| 144 | * |
| 145 | * @return TRUE if we unblocked the next sub-stream, FALSE if not |
| 146 | * |
| 147 | * @throws IOException |
| 148 | * in case of I/O error or if the stream is closed |
| 149 | */ |
| 150 | public boolean next() throws IOException { |
| 151 | return next(false); |
| 152 | } |
| 153 | |
| 154 | /** |
| 155 | * Unblock the next sub-stream as would have done |
| 156 | * {@link NextableInputStream#next()}, but disable the sub-stream systems. |
| 157 | * <p> |
| 158 | * That is, the next stream, if any, will be the last one and will not be |
| 159 | * subject to the {@link NextableInputStreamStep}. |
| 160 | * |
| 161 | * @return TRUE if we unblocked the next sub-stream, FALSE if not |
| 162 | * |
| 163 | * @throws IOException |
| 164 | * in case of I/O error or if the stream is closed |
| 165 | */ |
| 166 | public boolean nextAll() throws IOException { |
| 167 | return next(true); |
| 168 | } |
| 169 | |
| 170 | // max is buffer.size ! |
| 171 | public boolean startsWiths(String search) throws IOException { |
| 172 | return startsWith(search.getBytes("UTF-8")); |
| 173 | } |
| 174 | |
| 175 | // max is buffer.size ! |
| 176 | public boolean startsWith(byte[] search) throws IOException { |
| 177 | if (search.length > originalBuffer.length) { |
| 178 | throw new IOException( |
| 179 | "This stream does not support searching for more than " |
| 180 | + buffer.length + " bytes"); |
| 181 | } |
| 182 | |
| 183 | checkClose(); |
| 184 | |
| 185 | if (available() < search.length) { |
| 186 | preRead(); |
| 187 | } |
| 188 | |
| 189 | if (available() >= search.length) { |
| 190 | // Easy path |
| 191 | return startsWith(search, buffer, pos); |
| 192 | } else if (!eof) { |
| 193 | // Harder path |
| 194 | if (buffer2 == null && buffer.length == originalBuffer.length) { |
| 195 | buffer2 = Arrays.copyOf(buffer, buffer.length * 2); |
| 196 | |
| 197 | pos2 = buffer.length; |
| 198 | len2 = in.read(buffer2, pos2, buffer.length); |
| 199 | if (len2 > 0) { |
| 200 | bytesRead += len2; |
| 201 | } |
| 202 | |
| 203 | // Note: here, len/len2 = INDEX of last good byte |
| 204 | len2 += pos2; |
| 205 | } |
| 206 | |
| 207 | if (available() + (len2 - pos2) >= search.length) { |
| 208 | return startsWith(search, buffer2, pos2); |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | return false; |
| 213 | } |
| 214 | |
| 215 | /** |
| 216 | * The number of bytes read from the under-laying {@link InputStream}. |
| 217 | * |
| 218 | * @return the number of bytes |
| 219 | */ |
| 220 | public long getBytesRead() { |
| 221 | return bytesRead; |
| 222 | } |
| 223 | |
| 224 | /** |
| 225 | * Check if this stream is totally spent (no more data to read or to |
| 226 | * process). |
| 227 | * |
| 228 | * @return TRUE if it is |
| 229 | */ |
| 230 | public boolean eof() { |
| 231 | return closed || (len < 0 && !hasMoreData()); |
| 232 | } |
| 233 | |
| 234 | @Override |
| 235 | public int read() throws IOException { |
| 236 | checkClose(); |
| 237 | |
| 238 | preRead(); |
| 239 | if (eof) { |
| 240 | return -1; |
| 241 | } |
| 242 | |
| 243 | return buffer[pos++]; |
| 244 | } |
| 245 | |
| 246 | @Override |
| 247 | public int read(byte[] b) throws IOException { |
| 248 | return read(b, 0, b.length); |
| 249 | } |
| 250 | |
| 251 | @Override |
| 252 | public int read(byte[] b, int boff, int blen) throws IOException { |
| 253 | checkClose(); |
| 254 | |
| 255 | if (b == null) { |
| 256 | throw new NullPointerException(); |
| 257 | } else if (boff < 0 || blen < 0 || blen > b.length - boff) { |
| 258 | throw new IndexOutOfBoundsException(); |
| 259 | } else if (blen == 0) { |
| 260 | return 0; |
| 261 | } |
| 262 | |
| 263 | int done = 0; |
| 264 | while (hasMoreData() && done < blen) { |
| 265 | preRead(); |
| 266 | if (hasMoreData()) { |
| 267 | for (int i = pos; i < blen && i < len; i++) { |
| 268 | b[boff + done] = buffer[i]; |
| 269 | pos++; |
| 270 | done++; |
| 271 | } |
| 272 | } |
| 273 | } |
| 274 | |
| 275 | return done > 0 ? done : -1; |
| 276 | } |
| 277 | |
| 278 | @Override |
| 279 | public long skip(long n) throws IOException { |
| 280 | if (n <= 0) { |
| 281 | return 0; |
| 282 | } |
| 283 | |
| 284 | long skipped = 0; |
| 285 | while (hasMoreData() && n > 0) { |
| 286 | preRead(); |
| 287 | |
| 288 | long inBuffer = Math.min(n, available()); |
| 289 | pos += inBuffer; |
| 290 | n -= inBuffer; |
| 291 | skipped += inBuffer; |
| 292 | } |
| 293 | |
| 294 | return skipped; |
| 295 | } |
| 296 | |
| 297 | @Override |
| 298 | public int available() { |
| 299 | if (closed) { |
| 300 | return 0; |
| 301 | } |
| 302 | |
| 303 | return Math.max(0, len - pos); |
| 304 | } |
| 305 | |
| 306 | /** |
| 307 | * Closes this stream and releases any system resources associated with the |
| 308 | * stream. |
| 309 | * <p> |
| 310 | * Including the under-laying {@link InputStream}. |
| 311 | * <p> |
| 312 | * <b>Note:</b> if you called the {@link NextableInputStream#open()} method |
| 313 | * prior to this one, it will just decrease the internal count of how many |
| 314 | * open streams it held and do nothing else. The stream will actually be |
| 315 | * closed when you have called {@link NextableInputStream#close()} once more |
| 316 | * than {@link NextableInputStream#open()}. |
| 317 | * |
| 318 | * @exception IOException |
| 319 | * in case of I/O error |
| 320 | */ |
| 321 | @Override |
| 322 | public synchronized void close() throws IOException { |
| 323 | close(true); |
| 324 | } |
| 325 | |
| 326 | /** |
| 327 | * Closes this stream and releases any system resources associated with the |
| 328 | * stream. |
| 329 | * <p> |
| 330 | * Including the under-laying {@link InputStream} if |
| 331 | * <tt>incudingSubStream</tt> is true. |
| 332 | * <p> |
| 333 | * You can call this method multiple times, it will not cause an |
| 334 | * {@link IOException} for subsequent calls. |
| 335 | * <p> |
| 336 | * <b>Note:</b> if you called the {@link NextableInputStream#open()} method |
| 337 | * prior to this one, it will just decrease the internal count of how many |
| 338 | * open streams it held and do nothing else. The stream will actually be |
| 339 | * closed when you have called {@link NextableInputStream#close()} once more |
| 340 | * than {@link NextableInputStream#open()}. |
| 341 | * |
| 342 | * @exception IOException |
| 343 | * in case of I/O error |
| 344 | */ |
| 345 | public synchronized void close(boolean includingSubStream) |
| 346 | throws IOException { |
| 347 | if (!closed) { |
| 348 | if (openCounter > 0) { |
| 349 | openCounter--; |
| 350 | } else { |
| 351 | closed = true; |
| 352 | if (includingSubStream && in != null) { |
| 353 | in.close(); |
| 354 | } |
| 355 | } |
| 356 | } |
| 357 | } |
| 358 | |
| 359 | /** |
| 360 | * Check if we still have some data in the buffer and, if not, fetch some. |
| 361 | * |
| 362 | * @return TRUE if we fetched some data, FALSE if there are still some in |
| 363 | * the buffer |
| 364 | * |
| 365 | * @throws IOException |
| 366 | * in case of I/O error |
| 367 | */ |
| 368 | private boolean preRead() throws IOException { |
| 369 | boolean hasRead = false; |
| 370 | if (!eof && in != null && pos >= len && !stopped) { |
| 371 | pos = 0; |
| 372 | if (buffer2 != null) { |
| 373 | buffer = buffer2; |
| 374 | pos = pos2; |
| 375 | len = len2; |
| 376 | |
| 377 | buffer2 = null; |
| 378 | pos2 = 0; |
| 379 | len2 = 0; |
| 380 | } else { |
| 381 | buffer = originalBuffer; |
| 382 | len = in.read(buffer); |
| 383 | if (len > 0) { |
| 384 | bytesRead += len; |
| 385 | } |
| 386 | } |
| 387 | |
| 388 | checkBuffer(true); |
| 389 | hasRead = true; |
| 390 | } |
| 391 | |
| 392 | if (pos >= len) { |
| 393 | eof = true; |
| 394 | } |
| 395 | |
| 396 | return hasRead; |
| 397 | } |
| 398 | |
| 399 | /** |
| 400 | * We have more data available in the buffer or we can fetch more. |
| 401 | * |
| 402 | * @return TRUE if it is the case, FALSE if not |
| 403 | */ |
| 404 | private boolean hasMoreData() { |
| 405 | return !closed && started && !(eof && pos >= len); |
| 406 | } |
| 407 | |
| 408 | /** |
| 409 | * Check that the buffer didn't overshot to the next item, and fix |
| 410 | * {@link NextableInputStream#len} if needed. |
| 411 | * <p> |
| 412 | * If {@link NextableInputStream#len} is fixed, |
| 413 | * {@link NextableInputStream#eof} and {@link NextableInputStream#stopped} |
| 414 | * are set to TRUE. |
| 415 | * |
| 416 | * @param newBuffer |
| 417 | * we changed the buffer, we need to clear some information in |
| 418 | * the {@link NextableInputStreamStep} |
| 419 | */ |
| 420 | private void checkBuffer(boolean newBuffer) { |
| 421 | if (step != null && len > 0) { |
| 422 | if (newBuffer) { |
| 423 | step.clearBuffer(); |
| 424 | } |
| 425 | |
| 426 | int stopAt = step.stop(buffer, pos, len); |
| 427 | if (stopAt >= 0) { |
| 428 | len = stopAt; |
| 429 | eof = true; |
| 430 | stopped = true; |
| 431 | } |
| 432 | } |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | * The implementation of {@link NextableInputStream#next()} and |
| 437 | * {@link NextableInputStream#nextAll()}. |
| 438 | * |
| 439 | * @param all |
| 440 | * TRUE for {@link NextableInputStream#nextAll()}, FALSE for |
| 441 | * {@link NextableInputStream#next()} |
| 442 | * |
| 443 | * @return TRUE if we unblocked the next sub-stream, FALSE if not |
| 444 | * |
| 445 | * @throws IOException |
| 446 | * in case of I/O error or if the stream is closed |
| 447 | */ |
| 448 | private boolean next(boolean all) throws IOException { |
| 449 | checkClose(); |
| 450 | |
| 451 | if (!started) { |
| 452 | // First call before being allowed to read |
| 453 | started = true; |
| 454 | |
| 455 | if (all) { |
| 456 | step = null; |
| 457 | } |
| 458 | |
| 459 | return true; |
| 460 | } |
| 461 | |
| 462 | if (step != null && !hasMoreData() && stopped) { |
| 463 | len = step.getResumeLen(); |
| 464 | pos += step.getResumeSkip(); |
| 465 | eof = false; |
| 466 | |
| 467 | if (all) { |
| 468 | step = null; |
| 469 | } |
| 470 | |
| 471 | if (!preRead()) { |
| 472 | checkBuffer(false); |
| 473 | } |
| 474 | |
| 475 | // consider that if EOF, there is no next |
| 476 | return hasMoreData(); |
| 477 | } |
| 478 | |
| 479 | return false; |
| 480 | } |
| 481 | |
| 482 | /** |
| 483 | * Check that the stream was not closed, and throw an {@link IOException} if |
| 484 | * it was. |
| 485 | * |
| 486 | * @throws IOException |
| 487 | * if it was closed |
| 488 | */ |
| 489 | private void checkClose() throws IOException { |
| 490 | if (closed) { |
| 491 | throw new IOException( |
| 492 | "This NextableInputStream was closed, you cannot use it anymore."); |
| 493 | } |
| 494 | } |
| 495 | |
| 496 | // buffer must be > search |
| 497 | static private boolean startsWith(byte[] search, byte[] buffer, |
| 498 | int offset) { |
| 499 | boolean same = true; |
| 500 | for (int i = 0; i < search.length; i++) { |
| 501 | if (search[i] != buffer[offset + i]) { |
| 502 | same = false; |
| 503 | break; |
| 504 | } |
| 505 | } |
| 506 | |
| 507 | return same; |
| 508 | } |
| 509 | } |