1 /* 2 * Copyright (c) 1994, 2018, 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 * Returns a new {@code InputStream} that reads no bytes. The returned 60 * stream is initially open. The stream is closed by calling the 61 * {@code close()} method. Subsequent calls to {@code close()} have no 62 * effect. 63 * 64 * <p> While the stream is open, the {@code available()}, {@code read()}, 65 * {@code read(byte[])}, {@code read(byte[], int, int)}, 66 * {@code readAllBytes()}, {@code readNBytes(byte[], int, int)}, 67 * {@code readNBytes(int)}, {@code skip()}, and 68 * {@code transferTo()} methods all behave as if end of stream has been 69 * reached. After the stream has been closed, these methods all throw 70 * {@code IOException}. 71 * 72 * <p> The {@code markSupported()} method returns {@code false}. The 73 * {@code mark()} method does nothing, and the {@code reset()} method 74 * throws {@code IOException}. 75 * 76 * @return an {@code InputStream} which contains no bytes 77 * 78 * @since 11 79 */ 80 public static InputStream nullInputStream() { 81 return new InputStream() { 82 private volatile boolean closed; 83 84 private void ensureOpen() throws IOException { 85 if (closed) { 86 throw new IOException("Stream closed"); 87 } 88 } 89 90 @Override 91 public int available () throws IOException { 92 ensureOpen(); 93 return 0; 94 } 95 96 @Override 97 public int read() throws IOException { 98 ensureOpen(); 99 return -1; 100 } 101 102 @Override 103 public int read(byte[] b, int off, int len) throws IOException { 104 Objects.checkFromIndexSize(off, len, b.length); 105 if (len == 0) { 106 return 0; 107 } 108 ensureOpen(); 109 return -1; 110 } 111 112 @Override 113 public byte[] readAllBytes() throws IOException { 114 ensureOpen(); 115 return new byte[0]; 116 } 117 118 @Override 119 public int readNBytes(byte[] b, int off, int len) 120 throws IOException { 121 Objects.checkFromIndexSize(off, len, b.length); 122 ensureOpen(); 123 return 0; 124 } 125 126 @Override 127 public byte[] readNBytes(int len) 128 throws IOException { 129 if (len < 0) { 130 throw new IllegalArgumentException("len < 0"); 131 } 132 ensureOpen(); 133 return new byte[0]; 134 } 135 136 @Override 137 public long skip(long n) throws IOException { 138 ensureOpen(); 139 return 0L; 140 } 141 142 @Override 143 public long transferTo(OutputStream out) throws IOException { 144 Objects.requireNonNull(out); 145 ensureOpen(); 146 return 0L; 147 } 148 149 @Override 150 public void close() throws IOException { 151 closed = true; 152 } 153 }; 154 } 155 156 /** 157 * Reads the next byte of data from the input stream. The value byte is 158 * returned as an <code>int</code> in the range <code>0</code> to 159 * <code>255</code>. If no byte is available because the end of the stream 160 * has been reached, the value <code>-1</code> is returned. This method 161 * blocks until input data is available, the end of the stream is detected, 162 * or an exception is thrown. 163 * 164 * <p> A subclass must provide an implementation of this method. 165 * 166 * @return the next byte of data, or <code>-1</code> if the end of the 167 * stream is reached. 168 * @exception IOException if an I/O error occurs. 169 */ 170 public abstract int read() throws IOException; 171 172 /** 173 * Reads some number of bytes from the input stream and stores them into 174 * the buffer array <code>b</code>. The number of bytes actually read is 175 * returned as an integer. This method blocks until input data is 176 * available, end of file is detected, or an exception is thrown. 177 * 178 * <p> If the length of <code>b</code> is zero, then no bytes are read and 179 * <code>0</code> is returned; otherwise, there is an attempt to read at 180 * least one byte. If no byte is available because the stream is at the 181 * end of the file, the value <code>-1</code> is returned; otherwise, at 182 * least one byte is read and stored into <code>b</code>. 183 * 184 * <p> The first byte read is stored into element <code>b[0]</code>, the 185 * next one into <code>b[1]</code>, and so on. The number of bytes read is, 186 * at most, equal to the length of <code>b</code>. Let <i>k</i> be the 187 * number of bytes actually read; these bytes will be stored in elements 188 * <code>b[0]</code> through <code>b[</code><i>k</i><code>-1]</code>, 189 * leaving elements <code>b[</code><i>k</i><code>]</code> through 190 * <code>b[b.length-1]</code> unaffected. 191 * 192 * <p> The <code>read(b)</code> method for class <code>InputStream</code> 193 * has the same effect as: <pre><code> read(b, 0, b.length) </code></pre> 194 * 195 * @param b the buffer into which the data is read. 196 * @return the total number of bytes read into the buffer, or 197 * <code>-1</code> if there is no more data because the end of 198 * the stream has been reached. 199 * @exception IOException If the first byte cannot be read for any reason 200 * other than the end of the file, if the input stream has been closed, or 201 * if some other I/O error occurs. 202 * @exception NullPointerException if <code>b</code> is <code>null</code>. 203 * @see java.io.InputStream#read(byte[], int, int) 204 */ 205 public int read(byte b[]) throws IOException { 206 return read(b, 0, b.length); 207 } 208 209 /** 210 * Reads up to <code>len</code> bytes of data from the input stream into 211 * an array of bytes. An attempt is made to read as many as 212 * <code>len</code> bytes, but a smaller number may be read. 213 * The number of bytes actually read is returned as an integer. 214 * 215 * <p> This method blocks until input data is available, end of file is 216 * detected, or an exception is thrown. 217 * 218 * <p> If <code>len</code> is zero, then no bytes are read and 219 * <code>0</code> is returned; otherwise, there is an attempt to read at 220 * least one byte. If no byte is available because the stream is at end of 221 * file, the value <code>-1</code> is returned; otherwise, at least one 222 * byte is read and stored into <code>b</code>. 223 * 224 * <p> The first byte read is stored into element <code>b[off]</code>, the 225 * next one into <code>b[off+1]</code>, and so on. The number of bytes read 226 * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of 227 * bytes actually read; these bytes will be stored in elements 228 * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>, 229 * leaving elements <code>b[off+</code><i>k</i><code>]</code> through 230 * <code>b[off+len-1]</code> unaffected. 231 * 232 * <p> In every case, elements <code>b[0]</code> through 233 * <code>b[off]</code> and elements <code>b[off+len]</code> through 234 * <code>b[b.length-1]</code> are unaffected. 235 * 236 * <p> The <code>read(b,</code> <code>off,</code> <code>len)</code> method 237 * for class <code>InputStream</code> simply calls the method 238 * <code>read()</code> repeatedly. If the first such call results in an 239 * <code>IOException</code>, that exception is returned from the call to 240 * the <code>read(b,</code> <code>off,</code> <code>len)</code> method. If 241 * any subsequent call to <code>read()</code> results in a 242 * <code>IOException</code>, the exception is caught and treated as if it 243 * were end of file; the bytes read up to that point are stored into 244 * <code>b</code> and the number of bytes read before the exception 245 * occurred is returned. The default implementation of this method blocks 246 * until the requested amount of input data <code>len</code> has been read, 247 * end of file is detected, or an exception is thrown. Subclasses are 248 * encouraged to provide a more efficient implementation of this method. 249 * 250 * @param b the buffer into which the data is read. 251 * @param off the start offset in array <code>b</code> 252 * at which the data is written. 253 * @param len the maximum number of bytes to read. 254 * @return the total number of bytes read into the buffer, or 255 * <code>-1</code> if there is no more data because the end of 256 * the stream has been reached. 257 * @exception IOException If the first byte cannot be read for any reason 258 * other than end of file, or if the input stream has been closed, or if 259 * some other I/O error occurs. 260 * @exception NullPointerException If <code>b</code> is <code>null</code>. 261 * @exception IndexOutOfBoundsException If <code>off</code> is negative, 262 * <code>len</code> is negative, or <code>len</code> is greater than 263 * <code>b.length - off</code> 264 * @see java.io.InputStream#read() 265 */ 266 public int read(byte b[], int off, int len) throws IOException { 267 Objects.checkFromIndexSize(off, len, b.length); 268 if (len == 0) { 269 return 0; 270 } 271 272 int c = read(); 273 if (c == -1) { 274 return -1; 275 } 276 b[off] = (byte)c; 277 278 int i = 1; 279 try { 280 for (; i < len ; i++) { 281 c = read(); 282 if (c == -1) { 283 break; 284 } 285 b[off + i] = (byte)c; 286 } 287 } catch (IOException ee) { 288 } 289 return i; 290 } 291 292 /** 293 * The maximum size of array to allocate. 294 * Some VMs reserve some header words in an array. 295 * Attempts to allocate larger arrays may result in 296 * OutOfMemoryError: Requested array size exceeds VM limit 297 */ 298 private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8; 299 300 /** 301 * Reads a number of bytes from the input stream. The number of bytes to 302 * read is specified by the {@code len} parameter which is interpreted as 303 * an inclusive upper bound on the number to read. This method blocks 304 * until the requested number of bytes have been read, end of stream is 305 * detected, or an exception is thrown. This method does not close the 306 * input stream. 307 * 308 * <p> If {@code len} is zero, then no bytes are read and an empty byte 309 * array is returned. 310 * 311 * <p> When this stream reaches end of stream, further invocations of this 312 * method will return an empty byte array. 313 * 314 * <p> Note that this method is intended for simple cases where it is 315 * convenient to read the specified number of bytes into a byte array. It 316 * is not intended for reading large amounts of data. 317 * 318 * <p> The behavior for the case where the input stream is <i>asynchronously 319 * closed</i>, or the thread interrupted during the read, is highly input 320 * stream specific, and therefore not specified. 321 * 322 * <p> If an I/O error occurs reading from the input stream, then it may do 323 * so after some, but not all, bytes have been read. Consequently the input 324 * stream may not be at end of stream and may be in an inconsistent state. 325 * It is strongly recommended that the stream be promptly closed if an I/O 326 * error occurs. 327 * 328 * @param len the maximum number of bytes to read 329 * @return a byte array containing the bytes read from this input stream 330 * @throws IllegalArgumentException if {@code len} is negative 331 * @throws IOException if an I/O error occurs 332 * @throws OutOfMemoryError if an array of the required size cannot be 333 * allocated. For example, if an array larger than {@code 2GB} would 334 * be required to store the bytes. 335 * 336 * @since 11 337 */ 338 private byte[] readAtMostNBytes(int len) 339 throws IOException { 340 if (len < 0) { 341 throw new IllegalArgumentException("len < 0"); 342 } 343 344 List<byte[]> bufs = null; 345 byte[] result = null; 346 int total = 0; 347 int remaining = len; 348 int n; 349 do { 350 byte[] buf = new byte[Math.min(len, DEFAULT_BUFFER_SIZE)]; 351 int nread = 0; 352 353 // read to EOF which may read more or less than buffer size 354 while ((n = read(buf, nread, 355 Math.min(buf.length - nread, remaining))) > 0) { 356 nread += n; 357 remaining -= n; 358 } 359 360 if (nread > 0) { 361 if (MAX_BUFFER_SIZE - total < nread) { 362 throw new OutOfMemoryError("Required array size too large"); 363 } 364 total += nread; 365 if (result == null) { 366 result = buf; 367 } else { 368 if (bufs == null) { 369 bufs = new ArrayList<>(); 370 bufs.add(result); 371 } 372 bufs.add(buf); 373 } 374 } 375 // if the last call to read returned -1 or the number of bytes 376 // requested have been read then break 377 } while (n >= 0 && remaining > 0); 378 379 if (bufs == null) { 380 if (result == null) { 381 return new byte[0]; 382 } 383 return result.length == total ? 384 result : Arrays.copyOf(result, total); 385 } 386 387 result = new byte[total]; 388 int offset = 0; 389 remaining = total; 390 for (byte[] b : bufs) { 391 int count = Math.min(b.length, remaining); 392 System.arraycopy(b, 0, result, offset, count); 393 offset += count; 394 remaining -= count; 395 } 396 397 return result; 398 } 399 400 /** 401 * Reads all remaining bytes from the input stream. This method blocks until 402 * all remaining bytes have been read and end of stream is detected, or an 403 * exception is thrown. This method does not close the input stream. 404 * 405 * <p> When this stream reaches end of stream, further invocations of this 406 * method will return an empty byte array. 407 * 408 * <p> Note that this method is intended for simple cases where it is 409 * convenient to read all bytes into a byte array. It is not intended for 410 * reading input streams with large amounts of data. 411 * 412 * <p> The behavior for the case where the input stream is <i>asynchronously 413 * closed</i>, or the thread interrupted during the read, is highly input 414 * stream specific, and therefore not specified. 415 * 416 * <p> If an I/O error occurs reading from the input stream, then it may do 417 * so after some, but not all, bytes have been read. Consequently the input 418 * stream may not be at end of stream and may be in an inconsistent state. 419 * It is strongly recommended that the stream be promptly closed if an I/O 420 * error occurs. 421 * 422 * @return a byte array containing the bytes read from this input stream 423 * @throws IOException if an I/O error occurs 424 * @throws OutOfMemoryError if an array of the required size cannot be 425 * allocated. For example, if an array larger than {@code 2GB} would 426 * be required to store the bytes. 427 * 428 * @since 9 429 */ 430 public byte[] readAllBytes() throws IOException { 431 return readAtMostNBytes(Integer.MAX_VALUE); 432 } 433 434 /** 435 * Reads up to a specified number of bytes from the input stream. This 436 * method blocks until the requested number of bytes have been read, end 437 * of stream is detected, or an exception is thrown. This method does not 438 * close the input stream. 439 * 440 * <p> The length of the returned array equals the number of bytes read 441 * from the stream. If {@code len} is zero, then no bytes are read and 442 * an empty byte array is returned. Otherwise, up to {@code len} bytes 443 * are read from the stream. Fewer than {@code len} bytes may be read if 444 * end of stream is encountered. 445 * 446 * <p> When this stream reaches end of stream, further invocations of this 447 * method will return an empty byte array. 448 * 449 * <p> Note that this method is intended for simple cases where it is 450 * convenient to read the specified number of bytes into a byte array. It 451 * is not intended for reading large amounts of data. 452 * 453 * <p> The behavior for the case where the input stream is <i>asynchronously 454 * closed</i>, or the thread interrupted during the read, is highly input 455 * stream specific, and therefore not specified. 456 * 457 * <p> If an I/O error occurs reading from the input stream, then it may do 458 * so after some, but not all, bytes have been read. Consequently the input 459 * stream may not be at end of stream and may be in an inconsistent state. 460 * It is strongly recommended that the stream be promptly closed if an I/O 461 * error occurs. 462 * 463 * @param len the maximum number of bytes to read 464 * @return a byte array containing the bytes read from this input stream 465 * @throws IllegalArgumentException if {@code length} is negative 466 * @throws IOException if an I/O error occurs 467 * @throws OutOfMemoryError if an array of the required size cannot be 468 * allocated. For example, if an array larger than {@code 2GB} would 469 * be required to store the bytes. 470 * 471 * @since 11 472 */ 473 public byte[] readNBytes(int len) throws IOException { 474 return readAtMostNBytes(len); 475 } 476 477 /** 478 * Reads the requested number of bytes from the input stream into the given 479 * byte array. This method blocks until {@code len} bytes of input data have 480 * been read, end of stream is detected, or an exception is thrown. The 481 * number of bytes actually read, possibly zero, is returned. This method 482 * does not close the input stream. 483 * 484 * <p> In the case where end of stream is reached before {@code len} bytes 485 * have been read, then the actual number of bytes read will be returned. 486 * When this stream reaches end of stream, further invocations of this 487 * method will return zero. 488 * 489 * <p> If {@code len} is zero, then no bytes are read and {@code 0} is 490 * returned; otherwise, there is an attempt to read up to {@code len} bytes. 491 * 492 * <p> The first byte read is stored into element {@code b[off]}, the next 493 * one in to {@code b[off+1]}, and so on. The number of bytes read is, at 494 * most, equal to {@code len}. Let <i>k</i> be the number of bytes actually 495 * read; these bytes will be stored in elements {@code b[off]} through 496 * {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code b[off+}<i>k</i> 497 * {@code ]} through {@code b[off+len-1]} unaffected. 498 * 499 * <p> The behavior for the case where the input stream is <i>asynchronously 500 * closed</i>, or the thread interrupted during the read, is highly input 501 * stream specific, and therefore not specified. 502 * 503 * <p> If an I/O error occurs reading from the input stream, then it may do 504 * so after some, but not all, bytes of {@code b} have been updated with 505 * data from the input stream. Consequently the input stream and {@code b} 506 * may be in an inconsistent state. It is strongly recommended that the 507 * stream be promptly closed if an I/O error occurs. 508 * 509 * @param b the byte array into which the data is read 510 * @param off the start offset in {@code b} at which the data is written 511 * @param len the maximum number of bytes to read 512 * @return the actual number of bytes read into the buffer 513 * @throws IOException if an I/O error occurs 514 * @throws NullPointerException if {@code b} is {@code null} 515 * @throws IndexOutOfBoundsException If {@code off} is negative, {@code len} 516 * is negative, or {@code len} is greater than {@code b.length - off} 517 * 518 * @since 9 519 */ 520 public int readNBytes(byte[] b, int off, int len) throws IOException { 521 Objects.checkFromIndexSize(off, len, b.length); 522 523 int n = 0; 524 while (n < len) { 525 int count = read(b, off + n, len - n); 526 if (count < 0) 527 break; 528 n += count; 529 } 530 return n; 531 } 532 533 /** 534 * Skips over and discards <code>n</code> bytes of data from this input 535 * stream. The <code>skip</code> method may, for a variety of reasons, end 536 * up skipping over some smaller number of bytes, possibly <code>0</code>. 537 * This may result from any of a number of conditions; reaching end of file 538 * before <code>n</code> bytes have been skipped is only one possibility. 539 * The actual number of bytes skipped is returned. If {@code n} is 540 * negative, the {@code skip} method for class {@code InputStream} always 541 * returns 0, and no bytes are skipped. Subclasses may handle the negative 542 * value differently. 543 * 544 * <p> The <code>skip</code> method implementation of this class creates a 545 * byte array and then repeatedly reads into it until <code>n</code> bytes 546 * have been read or the end of the stream has been reached. Subclasses are 547 * encouraged to provide a more efficient implementation of this method. 548 * For instance, the implementation may depend on the ability to seek. 549 * 550 * @param n the number of bytes to be skipped. 551 * @return the actual number of bytes skipped. 552 * @throws IOException if an I/O error occurs. 553 */ 554 public long skip(long n) throws IOException { 555 556 long remaining = n; 557 int nr; 558 559 if (n <= 0) { 560 return 0; 561 } 562 563 int size = (int)Math.min(MAX_SKIP_BUFFER_SIZE, remaining); 564 byte[] skipBuffer = new byte[size]; 565 while (remaining > 0) { 566 nr = read(skipBuffer, 0, (int)Math.min(size, remaining)); 567 if (nr < 0) { 568 break; 569 } 570 remaining -= nr; 571 } 572 573 return n - remaining; 574 } 575 576 /** 577 * Returns an estimate of the number of bytes that can be read (or 578 * skipped over) from this input stream without blocking by the next 579 * invocation of a method for this input stream. The next invocation 580 * might be the same thread or another thread. A single read or skip of this 581 * many bytes will not block, but may read or skip fewer bytes. 582 * 583 * <p> Note that while some implementations of {@code InputStream} will return 584 * the total number of bytes in the stream, many will not. It is 585 * never correct to use the return value of this method to allocate 586 * a buffer intended to hold all data in this stream. 587 * 588 * <p> A subclass' implementation of this method may choose to throw an 589 * {@link IOException} if this input stream has been closed by 590 * invoking the {@link #close()} method. 591 * 592 * <p> The {@code available} method for class {@code InputStream} always 593 * returns {@code 0}. 594 * 595 * <p> This method should be overridden by subclasses. 596 * 597 * @return an estimate of the number of bytes that can be read (or skipped 598 * over) from this input stream without blocking or {@code 0} when 599 * it reaches the end of the input stream. 600 * @exception IOException if an I/O error occurs. 601 */ 602 public int available() throws IOException { 603 return 0; 604 } 605 606 /** 607 * Closes this input stream and releases any system resources associated 608 * with the stream. 609 * 610 * <p> The <code>close</code> method of <code>InputStream</code> does 611 * nothing. 612 * 613 * @exception IOException if an I/O error occurs. 614 */ 615 public void close() throws IOException {} 616 617 /** 618 * Marks the current position in this input stream. A subsequent call to 619 * the <code>reset</code> method repositions this stream at the last marked 620 * position so that subsequent reads re-read the same bytes. 621 * 622 * <p> The <code>readlimit</code> arguments tells this input stream to 623 * allow that many bytes to be read before the mark position gets 624 * invalidated. 625 * 626 * <p> The general contract of <code>mark</code> is that, if the method 627 * <code>markSupported</code> returns <code>true</code>, the stream somehow 628 * remembers all the bytes read after the call to <code>mark</code> and 629 * stands ready to supply those same bytes again if and whenever the method 630 * <code>reset</code> is called. However, the stream is not required to 631 * remember any data at all if more than <code>readlimit</code> bytes are 632 * read from the stream before <code>reset</code> is called. 633 * 634 * <p> Marking a closed stream should not have any effect on the stream. 635 * 636 * <p> The <code>mark</code> method of <code>InputStream</code> does 637 * nothing. 638 * 639 * @param readlimit the maximum limit of bytes that can be read before 640 * the mark position becomes invalid. 641 * @see java.io.InputStream#reset() 642 */ 643 public synchronized void mark(int readlimit) {} 644 645 /** 646 * Repositions this stream to the position at the time the 647 * <code>mark</code> method was last called on this input stream. 648 * 649 * <p> The general contract of <code>reset</code> is: 650 * 651 * <ul> 652 * <li> If the method <code>markSupported</code> returns 653 * <code>true</code>, then: 654 * 655 * <ul><li> If the method <code>mark</code> has not been called since 656 * the stream was created, or the number of bytes read from the stream 657 * since <code>mark</code> was last called is larger than the argument 658 * to <code>mark</code> at that last call, then an 659 * <code>IOException</code> might be thrown. 660 * 661 * <li> If such an <code>IOException</code> is not thrown, then the 662 * stream is reset to a state such that all the bytes read since the 663 * most recent call to <code>mark</code> (or since the start of the 664 * file, if <code>mark</code> has not been called) will be resupplied 665 * to subsequent callers of the <code>read</code> method, followed by 666 * any bytes that otherwise would have been the next input data as of 667 * the time of the call to <code>reset</code>. </ul> 668 * 669 * <li> If the method <code>markSupported</code> returns 670 * <code>false</code>, then: 671 * 672 * <ul><li> The call to <code>reset</code> may throw an 673 * <code>IOException</code>. 674 * 675 * <li> If an <code>IOException</code> is not thrown, then the stream 676 * is reset to a fixed state that depends on the particular type of the 677 * input stream and how it was created. The bytes that will be supplied 678 * to subsequent callers of the <code>read</code> method depend on the 679 * particular type of the input stream. </ul></ul> 680 * 681 * <p>The method <code>reset</code> for class <code>InputStream</code> 682 * does nothing except throw an <code>IOException</code>. 683 * 684 * @exception IOException if this stream has not been marked or if the 685 * mark has been invalidated. 686 * @see java.io.InputStream#mark(int) 687 * @see java.io.IOException 688 */ 689 public synchronized void reset() throws IOException { 690 throw new IOException("mark/reset not supported"); 691 } 692 693 /** 694 * Tests if this input stream supports the <code>mark</code> and 695 * <code>reset</code> methods. Whether or not <code>mark</code> and 696 * <code>reset</code> are supported is an invariant property of a 697 * particular input stream instance. The <code>markSupported</code> method 698 * of <code>InputStream</code> returns <code>false</code>. 699 * 700 * @return <code>true</code> if this stream instance supports the mark 701 * and reset methods; <code>false</code> otherwise. 702 * @see java.io.InputStream#mark(int) 703 * @see java.io.InputStream#reset() 704 */ 705 public boolean markSupported() { 706 return false; 707 } 708 709 /** 710 * Reads all bytes from this input stream and writes the bytes to the 711 * given output stream in the order that they are read. On return, this 712 * input stream will be at end of stream. This method does not close either 713 * stream. 714 * <p> 715 * This method may block indefinitely reading from the input stream, or 716 * writing to the output stream. The behavior for the case where the input 717 * and/or output stream is <i>asynchronously closed</i>, or the thread 718 * interrupted during the transfer, is highly input and output stream 719 * specific, and therefore not specified. 720 * <p> 721 * If an I/O error occurs reading from the input stream or writing to the 722 * output stream, then it may do so after some bytes have been read or 723 * written. Consequently the input stream may not be at end of stream and 724 * one, or both, streams may be in an inconsistent state. It is strongly 725 * recommended that both streams be promptly closed if an I/O error occurs. 726 * 727 * @param out the output stream, non-null 728 * @return the number of bytes transferred 729 * @throws IOException if an I/O error occurs when reading or writing 730 * @throws NullPointerException if {@code out} is {@code null} 731 * 732 * @since 9 733 */ 734 public long transferTo(OutputStream out) throws IOException { 735 Objects.requireNonNull(out, "out"); 736 long transferred = 0; 737 byte[] buffer = new byte[DEFAULT_BUFFER_SIZE]; 738 int read; 739 while ((read = this.read(buffer, 0, DEFAULT_BUFFER_SIZE)) >= 0) { 740 out.write(buffer, 0, read); 741 transferred += read; 742 } 743 return transferred; 744 } 745 }