1 /* 2 * Copyright (c) 1994, 2019, 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.io; 27 28 import java.util.ArrayList; 29 import java.util.Arrays; 30 import java.util.List; 31 import java.util.Objects; 32 33 /** 34 * This abstract class is the superclass of all classes representing 35 * an input stream of bytes. 36 * 37 * <p> Applications that need to define a subclass of <code>InputStream</code> 38 * must always provide a method that returns the next byte of input. 39 * 40 * @author Arthur van Hoff 41 * @see java.io.BufferedInputStream 42 * @see java.io.ByteArrayInputStream 43 * @see java.io.DataInputStream 44 * @see java.io.FilterInputStream 45 * @see java.io.InputStream#read() 46 * @see java.io.OutputStream 47 * @see java.io.PushbackInputStream 48 * @since 1.0 49 */ 50 public abstract class InputStream implements Closeable { 51 52 // MAX_SKIP_BUFFER_SIZE is used to determine the maximum buffer size to 53 // use when skipping. 54 private static final int MAX_SKIP_BUFFER_SIZE = 2048; 55 56 private static final int DEFAULT_BUFFER_SIZE = 8192; 57 58 /** 59 * Constructor for subclasses to call. 60 */ 61 public InputStream() {} 62 63 /** 64 * Returns a new {@code InputStream} that reads no bytes. The returned 65 * stream is initially open. The stream is closed by calling the 66 * {@code close()} method. Subsequent calls to {@code close()} have no 67 * effect. 68 * 69 * <p> While the stream is open, the {@code available()}, {@code read()}, 70 * {@code read(byte[])}, {@code read(byte[], int, int)}, 71 * {@code readAllBytes()}, {@code readNBytes(byte[], int, int)}, 72 * {@code readNBytes(int)}, {@code skip(long)}, {@code skipNBytes(long)}, 73 * and {@code transferTo()} methods all behave as if end of stream has been 74 * reached. After the stream has been closed, these methods all throw 75 * {@code IOException}. 76 * 77 * <p> The {@code markSupported()} method returns {@code false}. The 78 * {@code mark()} method does nothing, and the {@code reset()} method 79 * throws {@code IOException}. 80 * 81 * @return an {@code InputStream} which contains no bytes 82 * 83 * @since 11 84 */ 85 public static InputStream nullInputStream() { 86 return new InputStream() { 87 private volatile boolean closed; 88 89 private void ensureOpen() throws IOException { 90 if (closed) { 91 throw new IOException("Stream closed"); 92 } 93 } 94 95 @Override 96 public int available () throws IOException { 97 ensureOpen(); 98 return 0; 99 } 100 101 @Override 102 public int read() throws IOException { 103 ensureOpen(); 104 return -1; 105 } 106 107 @Override 108 public int read(byte[] b, int off, int len) throws IOException { 109 Objects.checkFromIndexSize(off, len, b.length); 110 if (len == 0) { 111 return 0; 112 } 113 ensureOpen(); 114 return -1; 115 } 116 117 @Override 118 public byte[] readAllBytes() throws IOException { 119 ensureOpen(); 120 return new byte[0]; 121 } 122 123 @Override 124 public int readNBytes(byte[] b, int off, int len) 125 throws IOException { 126 Objects.checkFromIndexSize(off, len, b.length); 127 ensureOpen(); 128 return 0; 129 } 130 131 @Override 132 public byte[] readNBytes(int len) throws IOException { 133 if (len < 0) { 134 throw new IllegalArgumentException("len < 0"); 135 } 136 ensureOpen(); 137 return new byte[0]; 138 } 139 140 @Override 141 public long skip(long n) throws IOException { 142 ensureOpen(); 143 return 0L; 144 } 145 146 @Override 147 public void skipNBytes(long n) throws IOException { 148 ensureOpen(); 149 if (n > 0) { 150 throw new EOFException(); 151 } 152 } 153 154 @Override 155 public long transferTo(OutputStream out) throws IOException { 156 Objects.requireNonNull(out); 157 ensureOpen(); 158 return 0L; 159 } 160 161 @Override 162 public void close() throws IOException { 163 closed = true; 164 } 165 }; 166 } 167 168 /** 169 * Reads the next byte of data from the input stream. The value byte is 170 * returned as an <code>int</code> in the range <code>0</code> to 171 * <code>255</code>. If no byte is available because the end of the stream 172 * has been reached, the value <code>-1</code> is returned. This method 173 * blocks until input data is available, the end of the stream is detected, 174 * or an exception is thrown. 175 * 176 * <p> A subclass must provide an implementation of this method. 177 * 178 * @return the next byte of data, or <code>-1</code> if the end of the 179 * stream is reached. 180 * @throws IOException if an I/O error occurs. 181 */ 182 public abstract int read() throws IOException; 183 184 /** 185 * Reads some number of bytes from the input stream and stores them into 186 * the buffer array <code>b</code>. The number of bytes actually read is 187 * returned as an integer. This method blocks until input data is 188 * available, end of file is detected, or an exception is thrown. 189 * 190 * <p> If the length of <code>b</code> is zero, then no bytes are read and 191 * <code>0</code> is returned; otherwise, there is an attempt to read at 192 * least one byte. If no byte is available because the stream is at the 193 * end of the file, the value <code>-1</code> is returned; otherwise, at 194 * least one byte is read and stored into <code>b</code>. 195 * 196 * <p> The first byte read is stored into element <code>b[0]</code>, the 197 * next one into <code>b[1]</code>, and so on. The number of bytes read is, 198 * at most, equal to the length of <code>b</code>. Let <i>k</i> be the 199 * number of bytes actually read; these bytes will be stored in elements 200 * <code>b[0]</code> through <code>b[</code><i>k</i><code>-1]</code>, 201 * leaving elements <code>b[</code><i>k</i><code>]</code> through 202 * <code>b[b.length-1]</code> unaffected. 203 * 204 * <p> The <code>read(b)</code> method for class <code>InputStream</code> 205 * has the same effect as: <pre><code> read(b, 0, b.length) </code></pre> 206 * 207 * @param b the buffer into which the data is read. 208 * @return the total number of bytes read into the buffer, or 209 * <code>-1</code> if there is no more data because the end of 210 * the stream has been reached. 211 * @throws IOException If the first byte cannot be read for any reason 212 * other than the end of the file, if the input stream has been 213 * closed, or if some other I/O error occurs. 214 * @throws NullPointerException if <code>b</code> is <code>null</code>. 215 * @see java.io.InputStream#read(byte[], int, int) 216 */ 217 public int read(byte b[]) throws IOException { 218 return read(b, 0, b.length); 219 } 220 221 /** 222 * Reads up to <code>len</code> bytes of data from the input stream into 223 * an array of bytes. An attempt is made to read as many as 224 * <code>len</code> bytes, but a smaller number may be read. 225 * The number of bytes actually read is returned as an integer. 226 * 227 * <p> This method blocks until input data is available, end of file is 228 * detected, or an exception is thrown. 229 * 230 * <p> If <code>len</code> is zero, then no bytes are read and 231 * <code>0</code> is returned; otherwise, there is an attempt to read at 232 * least one byte. If no byte is available because the stream is at end of 233 * file, the value <code>-1</code> is returned; otherwise, at least one 234 * byte is read and stored into <code>b</code>. 235 * 236 * <p> The first byte read is stored into element <code>b[off]</code>, the 237 * next one into <code>b[off+1]</code>, and so on. The number of bytes read 238 * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of 239 * bytes actually read; these bytes will be stored in elements 240 * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>, 241 * leaving elements <code>b[off+</code><i>k</i><code>]</code> through 242 * <code>b[off+len-1]</code> unaffected. 243 * 244 * <p> In every case, elements <code>b[0]</code> through 245 * <code>b[off-1]</code> and elements <code>b[off+len]</code> through 246 * <code>b[b.length-1]</code> are unaffected. 247 * 248 * <p> The <code>read(b,</code> <code>off,</code> <code>len)</code> method 249 * for class <code>InputStream</code> simply calls the method 250 * <code>read()</code> repeatedly. If the first such call results in an 251 * <code>IOException</code>, that exception is returned from the call to 252 * the <code>read(b,</code> <code>off,</code> <code>len)</code> method. If 253 * any subsequent call to <code>read()</code> results in a 254 * <code>IOException</code>, the exception is caught and treated as if it 255 * were end of file; the bytes read up to that point are stored into 256 * <code>b</code> and the number of bytes read before the exception 257 * occurred is returned. The default implementation of this method blocks 258 * until the requested amount of input data <code>len</code> has been read, 259 * end of file is detected, or an exception is thrown. Subclasses are 260 * encouraged to provide a more efficient implementation of this method. 261 * 262 * @param b the buffer into which the data is read. 263 * @param off the start offset in array <code>b</code> 264 * at which the data is written. 265 * @param len the maximum number of bytes to read. 266 * @return the total number of bytes read into the buffer, or 267 * <code>-1</code> if there is no more data because the end of 268 * the stream has been reached. 269 * @throws IOException If the first byte cannot be read for any reason 270 * other than end of file, or if the input stream has been closed, 271 * or if some other I/O error occurs. 272 * @throws NullPointerException If <code>b</code> is <code>null</code>. 273 * @throws IndexOutOfBoundsException If <code>off</code> is negative, 274 * <code>len</code> is negative, or <code>len</code> is greater than 275 * <code>b.length - off</code> 276 * @see java.io.InputStream#read() 277 */ 278 public int read(byte b[], int off, int len) throws IOException { 279 Objects.checkFromIndexSize(off, len, b.length); 280 if (len == 0) { 281 return 0; 282 } 283 284 int c = read(); 285 if (c == -1) { 286 return -1; 287 } 288 b[off] = (byte)c; 289 290 int i = 1; 291 try { 292 for (; i < len ; i++) { 293 c = read(); 294 if (c == -1) { 295 break; 296 } 297 b[off + i] = (byte)c; 298 } 299 } catch (IOException ee) { 300 } 301 return i; 302 } 303 304 /** 305 * The maximum size of array to allocate. 306 * Some VMs reserve some header words in an array. 307 * Attempts to allocate larger arrays may result in 308 * OutOfMemoryError: Requested array size exceeds VM limit 309 */ 310 private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8; 311 312 /** 313 * Reads all remaining bytes from the input stream. This method blocks until 314 * all remaining bytes have been read and end of stream is detected, or an 315 * exception is thrown. This method does not close the input stream. 316 * 317 * <p> When this stream reaches end of stream, further invocations of this 318 * method will return an empty byte array. 319 * 320 * <p> Note that this method is intended for simple cases where it is 321 * convenient to read all bytes into a byte array. It is not intended for 322 * reading input streams with large amounts of data. 323 * 324 * <p> The behavior for the case where the input stream is <i>asynchronously 325 * closed</i>, or the thread interrupted during the read, is highly input 326 * stream specific, and therefore not specified. 327 * 328 * <p> If an I/O error occurs reading from the input stream, then it may do 329 * so after some, but not all, bytes have been read. Consequently the input 330 * stream may not be at end of stream and may be in an inconsistent state. 331 * It is strongly recommended that the stream be promptly closed if an I/O 332 * error occurs. 333 * 334 * @implSpec 335 * This method invokes {@link #readNBytes(int)} with a length of 336 * {@link Integer#MAX_VALUE}. 337 * 338 * @return a byte array containing the bytes read from this input stream 339 * @throws IOException if an I/O error occurs 340 * @throws OutOfMemoryError if an array of the required size cannot be 341 * allocated. 342 * 343 * @since 9 344 */ 345 public byte[] readAllBytes() throws IOException { 346 return readNBytes(Integer.MAX_VALUE); 347 } 348 349 /** 350 * Reads up to a specified number of bytes from the input stream. This 351 * method blocks until the requested number of bytes have been read, end 352 * of stream is detected, or an exception is thrown. This method does not 353 * close the input stream. 354 * 355 * <p> The length of the returned array equals the number of bytes read 356 * from the stream. If {@code len} is zero, then no bytes are read and 357 * an empty byte array is returned. Otherwise, up to {@code len} bytes 358 * are read from the stream. Fewer than {@code len} bytes may be read if 359 * end of stream is encountered. 360 * 361 * <p> When this stream reaches end of stream, further invocations of this 362 * method will return an empty byte array. 363 * 364 * <p> Note that this method is intended for simple cases where it is 365 * convenient to read the specified number of bytes into a byte array. The 366 * total amount of memory allocated by this method is proportional to the 367 * number of bytes read from the stream which is bounded by {@code len}. 368 * Therefore, the method may be safely called with very large values of 369 * {@code len} provided sufficient memory is available. 370 * 371 * <p> The behavior for the case where the input stream is <i>asynchronously 372 * closed</i>, or the thread interrupted during the read, is highly input 373 * stream specific, and therefore not specified. 374 * 375 * <p> If an I/O error occurs reading from the input stream, then it may do 376 * so after some, but not all, bytes have been read. Consequently the input 377 * stream may not be at end of stream and may be in an inconsistent state. 378 * It is strongly recommended that the stream be promptly closed if an I/O 379 * error occurs. 380 * 381 * @implNote 382 * The number of bytes allocated to read data from this stream and return 383 * the result is bounded by {@code 2*(long)len}, inclusive. 384 * 385 * @param len the maximum number of bytes to read 386 * @return a byte array containing the bytes read from this input stream 387 * @throws IllegalArgumentException if {@code length} is negative 388 * @throws IOException if an I/O error occurs 389 * @throws OutOfMemoryError if an array of the required size cannot be 390 * allocated. 391 * 392 * @since 11 393 */ 394 public byte[] readNBytes(int len) throws IOException { 395 if (len < 0) { 396 throw new IllegalArgumentException("len < 0"); 397 } 398 399 List<byte[]> bufs = null; 400 byte[] result = null; 401 int total = 0; 402 int remaining = len; 403 int n; 404 do { 405 byte[] buf = new byte[Math.min(remaining, DEFAULT_BUFFER_SIZE)]; 406 int nread = 0; 407 408 // read to EOF which may read more or less than buffer size 409 while ((n = read(buf, nread, 410 Math.min(buf.length - nread, remaining))) > 0) { 411 nread += n; 412 remaining -= n; 413 } 414 415 if (nread > 0) { 416 if (MAX_BUFFER_SIZE - total < nread) { 417 throw new OutOfMemoryError("Required array size too large"); 418 } 419 total += nread; 420 if (result == null) { 421 result = buf; 422 } else { 423 if (bufs == null) { 424 bufs = new ArrayList<>(); 425 bufs.add(result); 426 } 427 bufs.add(buf); 428 } 429 } 430 // if the last call to read returned -1 or the number of bytes 431 // requested have been read then break 432 } while (n >= 0 && remaining > 0); 433 434 if (bufs == null) { 435 if (result == null) { 436 return new byte[0]; 437 } 438 return result.length == total ? 439 result : Arrays.copyOf(result, total); 440 } 441 442 result = new byte[total]; 443 int offset = 0; 444 remaining = total; 445 for (byte[] b : bufs) { 446 int count = Math.min(b.length, remaining); 447 System.arraycopy(b, 0, result, offset, count); 448 offset += count; 449 remaining -= count; 450 } 451 452 return result; 453 } 454 455 /** 456 * Reads the requested number of bytes from the input stream into the given 457 * byte array. This method blocks until {@code len} bytes of input data have 458 * been read, end of stream is detected, or an exception is thrown. The 459 * number of bytes actually read, possibly zero, is returned. This method 460 * does not close the input stream. 461 * 462 * <p> In the case where end of stream is reached before {@code len} bytes 463 * have been read, then the actual number of bytes read will be returned. 464 * When this stream reaches end of stream, further invocations of this 465 * method will return zero. 466 * 467 * <p> If {@code len} is zero, then no bytes are read and {@code 0} is 468 * returned; otherwise, there is an attempt to read up to {@code len} bytes. 469 * 470 * <p> The first byte read is stored into element {@code b[off]}, the next 471 * one in to {@code b[off+1]}, and so on. The number of bytes read is, at 472 * most, equal to {@code len}. Let <i>k</i> be the number of bytes actually 473 * read; these bytes will be stored in elements {@code b[off]} through 474 * {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code b[off+}<i>k</i> 475 * {@code ]} through {@code b[off+len-1]} unaffected. 476 * 477 * <p> The behavior for the case where the input stream is <i>asynchronously 478 * closed</i>, or the thread interrupted during the read, is highly input 479 * stream specific, and therefore not specified. 480 * 481 * <p> If an I/O error occurs reading from the input stream, then it may do 482 * so after some, but not all, bytes of {@code b} have been updated with 483 * data from the input stream. Consequently the input stream and {@code b} 484 * may be in an inconsistent state. It is strongly recommended that the 485 * stream be promptly closed if an I/O error occurs. 486 * 487 * @param b the byte array into which the data is read 488 * @param off the start offset in {@code b} at which the data is written 489 * @param len the maximum number of bytes to read 490 * @return the actual number of bytes read into the buffer 491 * @throws IOException if an I/O error occurs 492 * @throws NullPointerException if {@code b} is {@code null} 493 * @throws IndexOutOfBoundsException If {@code off} is negative, {@code len} 494 * is negative, or {@code len} is greater than {@code b.length - off} 495 * 496 * @since 9 497 */ 498 public int readNBytes(byte[] b, int off, int len) throws IOException { 499 Objects.checkFromIndexSize(off, len, b.length); 500 501 int n = 0; 502 while (n < len) { 503 int count = read(b, off + n, len - n); 504 if (count < 0) 505 break; 506 n += count; 507 } 508 return n; 509 } 510 511 /** 512 * Skips over and discards <code>n</code> bytes of data from this input 513 * stream. The <code>skip</code> method may, for a variety of reasons, end 514 * up skipping over some smaller number of bytes, possibly <code>0</code>. 515 * This may result from any of a number of conditions; reaching end of file 516 * before <code>n</code> bytes have been skipped is only one possibility. 517 * The actual number of bytes skipped is returned. If {@code n} is 518 * negative, the {@code skip} method for class {@code InputStream} always 519 * returns 0, and no bytes are skipped. Subclasses may handle the negative 520 * value differently. 521 * 522 * <p> The <code>skip</code> method implementation of this class creates a 523 * byte array and then repeatedly reads into it until <code>n</code> bytes 524 * have been read or the end of the stream has been reached. Subclasses are 525 * encouraged to provide a more efficient implementation of this method. 526 * For instance, the implementation may depend on the ability to seek. 527 * 528 * @param n the number of bytes to be skipped. 529 * @return the actual number of bytes skipped which might be zero. 530 * @throws IOException if an I/O error occurs. 531 * @see java.io.InputStream#skipNBytes(long) 532 */ 533 public long skip(long n) throws IOException { 534 long remaining = n; 535 int nr; 536 537 if (n <= 0) { 538 return 0; 539 } 540 541 int size = (int)Math.min(MAX_SKIP_BUFFER_SIZE, remaining); 542 byte[] skipBuffer = new byte[size]; 543 while (remaining > 0) { 544 nr = read(skipBuffer, 0, (int)Math.min(size, remaining)); 545 if (nr < 0) { 546 break; 547 } 548 remaining -= nr; 549 } 550 551 return n - remaining; 552 } 553 554 /** 555 * Skips over and discards exactly {@code n} bytes of data from this input 556 * stream. If {@code n} is zero, then no bytes are skipped. 557 * If {@code n} is negative, then no bytes are skipped. 558 * Subclasses may handle the negative value differently. 559 * 560 * <p> This method blocks until the requested number of bytes have been 561 * skipped, end of file is reached, or an exception is thrown. 562 * 563 * <p> If end of stream is reached before the stream is at the desired 564 * position, then an {@code EOFException} is thrown. 565 * 566 * <p> If an I/O error occurs, then the input stream may be 567 * in an inconsistent state. It is strongly recommended that the 568 * stream be promptly closed if an I/O error occurs. 569 * 570 * @implNote 571 * Subclasses are encouraged to provide a more efficient implementation 572 * of this method. 573 * 574 * @implSpec 575 * If {@code n} is zero or negative, then no bytes are skipped. 576 * If {@code n} is positive, the default implementation of this method 577 * invokes {@link #skip(long) skip()} with parameter {@code n}. If the 578 * return value of {@code skip(n)} is non-negative and less than {@code n}, 579 * then {@link #read()} is invoked repeatedly until the stream is {@code n} 580 * bytes beyond its position when this method was invoked or end of stream 581 * is reached. If the return value of {@code skip(n)} is negative or 582 * greater than {@code n}, then an {@code IOException} is thrown. Any 583 * exception thrown by {@code skip()} or {@code read()} will be propagated. 584 * 585 * @param n the number of bytes to be skipped. 586 * @throws EOFException if end of stream is encountered before the 587 * stream can be positioned {@code n} bytes beyond its position 588 * when this method was invoked. 589 * @throws IOException if the stream cannot be positioned properly or 590 * if an I/O error occurs. 591 * @see java.io.InputStream#skip(long) 592 */ 593 public void skipNBytes(long n) throws IOException { 594 if (n > 0) { 595 long ns = skip(n); 596 if (ns >= 0 && ns < n) { // skipped too few bytes 597 // adjust number to skip 598 n -= ns; 599 // read until requested number skipped or EOS reached 600 while (n > 0 && read() != -1) { 601 n--; 602 } 603 // if not enough skipped, then EOFE 604 if (n != 0) { 605 throw new EOFException(); 606 } 607 } else if (ns != n) { // skipped negative or too many bytes 608 throw new IOException("Unable to skip exactly"); 609 } 610 } 611 } 612 613 /** 614 * Returns an estimate of the number of bytes that can be read (or skipped 615 * over) from this input stream without blocking, which may be 0, or 0 when 616 * end of stream is detected. The read might be on the same thread or 617 * another thread. A single read or skip of this many bytes will not block, 618 * but may read or skip fewer bytes. 619 * 620 * <p> Note that while some implementations of {@code InputStream} will 621 * return the total number of bytes in the stream, many will not. It is 622 * never correct to use the return value of this method to allocate 623 * a buffer intended to hold all data in this stream. 624 * 625 * <p> A subclass's implementation of this method may choose to throw an 626 * {@link IOException} if this input stream has been closed by invoking the 627 * {@link #close()} method. 628 * 629 * <p> The {@code available} method of {@code InputStream} always returns 630 * {@code 0}. 631 * 632 * <p> This method should be overridden by subclasses. 633 * 634 * @return an estimate of the number of bytes that can be read (or 635 * skipped over) from this input stream without blocking or 636 * {@code 0} when it reaches the end of the input stream. 637 * @throws IOException if an I/O error occurs. 638 */ 639 public int available() throws IOException { 640 return 0; 641 } 642 643 /** 644 * Closes this input stream and releases any system resources associated 645 * with the stream. 646 * 647 * <p> The <code>close</code> method of <code>InputStream</code> does 648 * nothing. 649 * 650 * @throws IOException if an I/O error occurs. 651 */ 652 public void close() throws IOException {} 653 654 /** 655 * Marks the current position in this input stream. A subsequent call to 656 * the <code>reset</code> method repositions this stream at the last marked 657 * position so that subsequent reads re-read the same bytes. 658 * 659 * <p> The <code>readlimit</code> arguments tells this input stream to 660 * allow that many bytes to be read before the mark position gets 661 * invalidated. 662 * 663 * <p> The general contract of <code>mark</code> is that, if the method 664 * <code>markSupported</code> returns <code>true</code>, the stream somehow 665 * remembers all the bytes read after the call to <code>mark</code> and 666 * stands ready to supply those same bytes again if and whenever the method 667 * <code>reset</code> is called. However, the stream is not required to 668 * remember any data at all if more than <code>readlimit</code> bytes are 669 * read from the stream before <code>reset</code> is called. 670 * 671 * <p> Marking a closed stream should not have any effect on the stream. 672 * 673 * <p> The <code>mark</code> method of <code>InputStream</code> does 674 * nothing. 675 * 676 * @param readlimit the maximum limit of bytes that can be read before 677 * the mark position becomes invalid. 678 * @see java.io.InputStream#reset() 679 */ 680 public synchronized void mark(int readlimit) {} 681 682 /** 683 * Repositions this stream to the position at the time the 684 * <code>mark</code> method was last called on this input stream. 685 * 686 * <p> The general contract of <code>reset</code> is: 687 * 688 * <ul> 689 * <li> If the method <code>markSupported</code> returns 690 * <code>true</code>, then: 691 * 692 * <ul><li> If the method <code>mark</code> has not been called since 693 * the stream was created, or the number of bytes read from the stream 694 * since <code>mark</code> was last called is larger than the argument 695 * to <code>mark</code> at that last call, then an 696 * <code>IOException</code> might be thrown. 697 * 698 * <li> If such an <code>IOException</code> is not thrown, then the 699 * stream is reset to a state such that all the bytes read since the 700 * most recent call to <code>mark</code> (or since the start of the 701 * file, if <code>mark</code> has not been called) will be resupplied 702 * to subsequent callers of the <code>read</code> method, followed by 703 * any bytes that otherwise would have been the next input data as of 704 * the time of the call to <code>reset</code>. </ul> 705 * 706 * <li> If the method <code>markSupported</code> returns 707 * <code>false</code>, then: 708 * 709 * <ul><li> The call to <code>reset</code> may throw an 710 * <code>IOException</code>. 711 * 712 * <li> If an <code>IOException</code> is not thrown, then the stream 713 * is reset to a fixed state that depends on the particular type of the 714 * input stream and how it was created. The bytes that will be supplied 715 * to subsequent callers of the <code>read</code> method depend on the 716 * particular type of the input stream. </ul></ul> 717 * 718 * <p>The method <code>reset</code> for class <code>InputStream</code> 719 * does nothing except throw an <code>IOException</code>. 720 * 721 * @throws IOException if this stream has not been marked or if the 722 * mark has been invalidated. 723 * @see java.io.InputStream#mark(int) 724 * @see java.io.IOException 725 */ 726 public synchronized void reset() throws IOException { 727 throw new IOException("mark/reset not supported"); 728 } 729 730 /** 731 * Tests if this input stream supports the <code>mark</code> and 732 * <code>reset</code> methods. Whether or not <code>mark</code> and 733 * <code>reset</code> are supported is an invariant property of a 734 * particular input stream instance. The <code>markSupported</code> method 735 * of <code>InputStream</code> returns <code>false</code>. 736 * 737 * @return <code>true</code> if this stream instance supports the mark 738 * and reset methods; <code>false</code> otherwise. 739 * @see java.io.InputStream#mark(int) 740 * @see java.io.InputStream#reset() 741 */ 742 public boolean markSupported() { 743 return false; 744 } 745 746 /** 747 * Reads all bytes from this input stream and writes the bytes to the 748 * given output stream in the order that they are read. On return, this 749 * input stream will be at end of stream. This method does not close either 750 * stream. 751 * <p> 752 * This method may block indefinitely reading from the input stream, or 753 * writing to the output stream. The behavior for the case where the input 754 * and/or output stream is <i>asynchronously closed</i>, or the thread 755 * interrupted during the transfer, is highly input and output stream 756 * specific, and therefore not specified. 757 * <p> 758 * If an I/O error occurs reading from the input stream or writing to the 759 * output stream, then it may do so after some bytes have been read or 760 * written. Consequently the input stream may not be at end of stream and 761 * one, or both, streams may be in an inconsistent state. It is strongly 762 * recommended that both streams be promptly closed if an I/O error occurs. 763 * 764 * @param out the output stream, non-null 765 * @return the number of bytes transferred 766 * @throws IOException if an I/O error occurs when reading or writing 767 * @throws NullPointerException if {@code out} is {@code null} 768 * 769 * @since 9 770 */ 771 public long transferTo(OutputStream out) throws IOException { 772 Objects.requireNonNull(out, "out"); 773 long transferred = 0; 774 byte[] buffer = new byte[DEFAULT_BUFFER_SIZE]; 775 int read; 776 while ((read = this.read(buffer, 0, DEFAULT_BUFFER_SIZE)) >= 0) { 777 out.write(buffer, 0, read); 778 transferred += read; 779 } 780 return transferred; 781 } 782 }