1 /* 2 * Copyright (c) 1994, 2017, 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.nio.channels.FileChannel; 29 import java.util.concurrent.atomic.AtomicBoolean; 30 import jdk.internal.misc.JavaIORandomAccessFileAccess; 31 import jdk.internal.misc.SharedSecrets; 32 import sun.nio.ch.FileChannelImpl; 33 34 35 /** 36 * Instances of this class support both reading and writing to a 37 * random access file. A random access file behaves like a large 38 * array of bytes stored in the file system. There is a kind of cursor, 39 * or index into the implied array, called the <em>file pointer</em>; 40 * input operations read bytes starting at the file pointer and advance 41 * the file pointer past the bytes read. If the random access file is 42 * created in read/write mode, then output operations are also available; 43 * output operations write bytes starting at the file pointer and advance 44 * the file pointer past the bytes written. Output operations that write 45 * past the current end of the implied array cause the array to be 46 * extended. The file pointer can be read by the 47 * {@code getFilePointer} method and set by the {@code seek} 48 * method. 49 * <p> 50 * It is generally true of all the reading routines in this class that 51 * if end-of-file is reached before the desired number of bytes has been 52 * read, an {@code EOFException} (which is a kind of 53 * {@code IOException}) is thrown. If any byte cannot be read for 54 * any reason other than end-of-file, an {@code IOException} other 55 * than {@code EOFException} is thrown. In particular, an 56 * {@code IOException} may be thrown if the stream has been closed. 57 * 58 * @author unascribed 59 * @since 1.0 60 */ 61 62 public class RandomAccessFile implements DataOutput, DataInput, Closeable { 63 64 private FileDescriptor fd; 65 private volatile FileChannel channel; 66 private boolean rw; 67 68 /** 69 * The path of the referenced file 70 * (null if the stream is created with a file descriptor) 71 */ 72 private final String path; 73 74 private final AtomicBoolean closed = new AtomicBoolean(false); 75 76 private static final int O_RDONLY = 1; 77 private static final int O_RDWR = 2; 78 private static final int O_SYNC = 4; 79 private static final int O_DSYNC = 8; 80 private static final int O_TEMPORARY = 16; 81 82 /** 83 * Creates a random access file stream to read from, and optionally 84 * to write to, a file with the specified name. A new 85 * {@link FileDescriptor} object is created to represent the 86 * connection to the file. 87 * 88 * <p> The {@code mode} argument specifies the access mode with which the 89 * file is to be opened. The permitted values and their meanings are as 90 * specified for the <a 91 * href="#mode">{@code RandomAccessFile(File,String)}</a> constructor. 92 * 93 * <p> 94 * If there is a security manager, its {@code checkRead} method 95 * is called with the {@code name} argument 96 * as its argument to see if read access to the file is allowed. 97 * If the mode allows writing, the security manager's 98 * {@code checkWrite} method 99 * is also called with the {@code name} argument 100 * as its argument to see if write access to the file is allowed. 101 * 102 * @param name the system-dependent filename 103 * @param mode the access <a href="#mode">mode</a> 104 * @exception IllegalArgumentException if the mode argument is not equal 105 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or 106 * {@code "rwd"} 107 * @exception FileNotFoundException 108 * if the mode is {@code "r"} but the given string does not 109 * denote an existing regular file, or if the mode begins with 110 * {@code "rw"} but the given string does not denote an 111 * existing, writable regular file and a new regular file of 112 * that name cannot be created, or if some other error occurs 113 * while opening or creating the file 114 * @exception SecurityException if a security manager exists and its 115 * {@code checkRead} method denies read access to the file 116 * or the mode is {@code "rw"} and the security manager's 117 * {@code checkWrite} method denies write access to the file 118 * @see java.lang.SecurityException 119 * @see java.lang.SecurityManager#checkRead(java.lang.String) 120 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 121 * @revised 1.4 122 * @spec JSR-51 123 */ 124 public RandomAccessFile(String name, String mode) 125 throws FileNotFoundException 126 { 127 this(name != null ? new File(name) : null, mode); 128 } 129 130 /** 131 * Creates a random access file stream to read from, and optionally to 132 * write to, the file specified by the {@link File} argument. A new {@link 133 * FileDescriptor} object is created to represent this file connection. 134 * 135 * <p>The <a id="mode">{@code mode}</a> argument specifies the access mode 136 * in which the file is to be opened. The permitted values and their 137 * meanings are: 138 * 139 * <table class="striped"> 140 * <caption style="display:none">Access mode permitted values and meanings</caption> 141 * <thead> 142 * <tr><th scope="col" style="text-align:left">Value</th><th scope="col" style="text-align:left">Meaning</th></tr> 143 * </thead> 144 * <tbody> 145 * <tr><th scope="row" style="vertical-align:top">{@code "r"}</th> 146 * <td> Open for reading only. Invoking any of the {@code write} 147 * methods of the resulting object will cause an 148 * {@link java.io.IOException} to be thrown.</td></tr> 149 * <tr><th scope="row" style="vertical-align:top">{@code "rw"}</th> 150 * <td> Open for reading and writing. If the file does not already 151 * exist then an attempt will be made to create it.</td></tr> 152 * <tr><th scope="row" style="vertical-align:top">{@code "rws"}</th> 153 * <td> Open for reading and writing, as with {@code "rw"}, and also 154 * require that every update to the file's content or metadata be 155 * written synchronously to the underlying storage device.</td></tr> 156 * <tr><th scope="row" style="vertical-align:top">{@code "rwd"}</th> 157 * <td> Open for reading and writing, as with {@code "rw"}, and also 158 * require that every update to the file's content be written 159 * synchronously to the underlying storage device.</td></tr> 160 * </tbody> 161 * </table> 162 * 163 * The {@code "rws"} and {@code "rwd"} modes work much like the {@link 164 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of 165 * the {@link java.nio.channels.FileChannel} class, passing arguments of 166 * {@code true} and {@code false}, respectively, except that they always 167 * apply to every I/O operation and are therefore often more efficient. If 168 * the file resides on a local storage device then when an invocation of a 169 * method of this class returns it is guaranteed that all changes made to 170 * the file by that invocation will have been written to that device. This 171 * is useful for ensuring that critical information is not lost in the 172 * event of a system crash. If the file does not reside on a local device 173 * then no such guarantee is made. 174 * 175 * <p>The {@code "rwd"} mode can be used to reduce the number of I/O 176 * operations performed. Using {@code "rwd"} only requires updates to the 177 * file's content to be written to storage; using {@code "rws"} requires 178 * updates to both the file's content and its metadata to be written, which 179 * generally requires at least one more low-level I/O operation. 180 * 181 * <p>If there is a security manager, its {@code checkRead} method is 182 * called with the pathname of the {@code file} argument as its 183 * argument to see if read access to the file is allowed. If the mode 184 * allows writing, the security manager's {@code checkWrite} method is 185 * also called with the path argument to see if write access to the file is 186 * allowed. 187 * 188 * @param file the file object 189 * @param mode the access mode, as described 190 * <a href="#mode">above</a> 191 * @exception IllegalArgumentException if the mode argument is not equal 192 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or 193 * {@code "rwd"} 194 * @exception FileNotFoundException 195 * if the mode is {@code "r"} but the given file object does 196 * not denote an existing regular file, or if the mode begins 197 * with {@code "rw"} but the given file object does not denote 198 * an existing, writable regular file and a new regular file of 199 * that name cannot be created, or if some other error occurs 200 * while opening or creating the file 201 * @exception SecurityException if a security manager exists and its 202 * {@code checkRead} method denies read access to the file 203 * or the mode is {@code "rw"} and the security manager's 204 * {@code checkWrite} method denies write access to the file 205 * @see java.lang.SecurityManager#checkRead(java.lang.String) 206 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 207 * @see java.nio.channels.FileChannel#force(boolean) 208 * @revised 1.4 209 * @spec JSR-51 210 */ 211 public RandomAccessFile(File file, String mode) 212 throws FileNotFoundException 213 { 214 this(file, mode, false); 215 } 216 217 private RandomAccessFile(File file, String mode, boolean openAndDelete) 218 throws FileNotFoundException 219 { 220 String name = (file != null ? file.getPath() : null); 221 int imode = -1; 222 if (mode.equals("r")) 223 imode = O_RDONLY; 224 else if (mode.startsWith("rw")) { 225 imode = O_RDWR; 226 rw = true; 227 if (mode.length() > 2) { 228 if (mode.equals("rws")) 229 imode |= O_SYNC; 230 else if (mode.equals("rwd")) 231 imode |= O_DSYNC; 232 else 233 imode = -1; 234 } 235 } 236 if (openAndDelete) 237 imode |= O_TEMPORARY; 238 if (imode < 0) 239 throw new IllegalArgumentException("Illegal mode \"" + mode 240 + "\" must be one of " 241 + "\"r\", \"rw\", \"rws\"," 242 + " or \"rwd\""); 243 SecurityManager security = System.getSecurityManager(); 244 if (security != null) { 245 security.checkRead(name); 246 if (rw) { 247 security.checkWrite(name); 248 } 249 } 250 if (name == null) { 251 throw new NullPointerException(); 252 } 253 if (file.isInvalid()) { 254 throw new FileNotFoundException("Invalid file path"); 255 } 256 fd = new FileDescriptor(); 257 fd.attach(this); 258 path = name; 259 open(name, imode); 260 FileCleanable.register(fd); // open sets the fd, register the cleanup 261 } 262 263 /** 264 * Returns the opaque file descriptor object associated with this 265 * stream. 266 * 267 * @return the file descriptor object associated with this stream. 268 * @exception IOException if an I/O error occurs. 269 * @see java.io.FileDescriptor 270 */ 271 public final FileDescriptor getFD() throws IOException { 272 if (fd != null) { 273 return fd; 274 } 275 throw new IOException(); 276 } 277 278 /** 279 * Returns the unique {@link java.nio.channels.FileChannel FileChannel} 280 * object associated with this file. 281 * 282 * <p> The {@link java.nio.channels.FileChannel#position() 283 * position} of the returned channel will always be equal to 284 * this object's file-pointer offset as returned by the {@link 285 * #getFilePointer getFilePointer} method. Changing this object's 286 * file-pointer offset, whether explicitly or by reading or writing bytes, 287 * will change the position of the channel, and vice versa. Changing the 288 * file's length via this object will change the length seen via the file 289 * channel, and vice versa. 290 * 291 * @return the file channel associated with this file 292 * 293 * @since 1.4 294 * @spec JSR-51 295 */ 296 public final FileChannel getChannel() { 297 FileChannel fc = this.channel; 298 if (fc == null) { 299 synchronized (this) { 300 fc = this.channel; 301 if (fc == null) { 302 this.channel = fc = FileChannelImpl.open(fd, path, true, 303 rw, false, this); 304 if (closed.get()) { 305 try { 306 fc.close(); 307 } catch (IOException ioe) { 308 throw new InternalError(ioe); // should not happen 309 } 310 } 311 } 312 } 313 } 314 return fc; 315 } 316 317 /** 318 * Opens a file and returns the file descriptor. The file is 319 * opened in read-write mode if the O_RDWR bit in {@code mode} 320 * is true, else the file is opened as read-only. 321 * If the {@code name} refers to a directory, an IOException 322 * is thrown. 323 * 324 * @param name the name of the file 325 * @param mode the mode flags, a combination of the O_ constants 326 * defined above 327 */ 328 private native void open0(String name, int mode) 329 throws FileNotFoundException; 330 331 // wrap native call to allow instrumentation 332 /** 333 * Opens a file and returns the file descriptor. The file is 334 * opened in read-write mode if the O_RDWR bit in {@code mode} 335 * is true, else the file is opened as read-only. 336 * If the {@code name} refers to a directory, an IOException 337 * is thrown. 338 * 339 * @param name the name of the file 340 * @param mode the mode flags, a combination of the O_ constants 341 * defined above 342 */ 343 private void open(String name, int mode) 344 throws FileNotFoundException { 345 open0(name, mode); 346 } 347 348 // 'Read' primitives 349 350 /** 351 * Reads a byte of data from this file. The byte is returned as an 352 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This 353 * method blocks if no input is yet available. 354 * <p> 355 * Although {@code RandomAccessFile} is not a subclass of 356 * {@code InputStream}, this method behaves in exactly the same 357 * way as the {@link InputStream#read()} method of 358 * {@code InputStream}. 359 * 360 * @return the next byte of data, or {@code -1} if the end of the 361 * file has been reached. 362 * @exception IOException if an I/O error occurs. Not thrown if 363 * end-of-file has been reached. 364 */ 365 public int read() throws IOException { 366 return read0(); 367 } 368 369 private native int read0() throws IOException; 370 371 /** 372 * Reads a sub array as a sequence of bytes. 373 * @param b the buffer into which the data is read. 374 * @param off the start offset of the data. 375 * @param len the number of bytes to read. 376 * @exception IOException If an I/O error has occurred. 377 */ 378 private native int readBytes(byte[] b, int off, int len) throws IOException; 379 380 /** 381 * Reads up to {@code len} bytes of data from this file into an 382 * array of bytes. This method blocks until at least one byte of input 383 * is available. 384 * <p> 385 * Although {@code RandomAccessFile} is not a subclass of 386 * {@code InputStream}, this method behaves in exactly the 387 * same way as the {@link InputStream#read(byte[], int, int)} method of 388 * {@code InputStream}. 389 * 390 * @param b the buffer into which the data is read. 391 * @param off the start offset in array {@code b} 392 * at which the data is written. 393 * @param len the maximum number of bytes read. 394 * @return the total number of bytes read into the buffer, or 395 * {@code -1} if there is no more data because the end of 396 * the file has been reached. 397 * @exception IOException If the first byte cannot be read for any reason 398 * other than end of file, or if the random access file has been closed, or if 399 * some other I/O error occurs. 400 * @exception NullPointerException If {@code b} is {@code null}. 401 * @exception IndexOutOfBoundsException If {@code off} is negative, 402 * {@code len} is negative, or {@code len} is greater than 403 * {@code b.length - off} 404 */ 405 public int read(byte[] b, int off, int len) throws IOException { 406 return readBytes(b, off, len); 407 } 408 409 /** 410 * Reads up to {@code b.length} bytes of data from this file 411 * into an array of bytes. This method blocks until at least one byte 412 * of input is available. 413 * <p> 414 * Although {@code RandomAccessFile} is not a subclass of 415 * {@code InputStream}, this method behaves in exactly the 416 * same way as the {@link InputStream#read(byte[])} method of 417 * {@code InputStream}. 418 * 419 * @param b the buffer into which the data is read. 420 * @return the total number of bytes read into the buffer, or 421 * {@code -1} if there is no more data because the end of 422 * this file has been reached. 423 * @exception IOException If the first byte cannot be read for any reason 424 * other than end of file, or if the random access file has been closed, or if 425 * some other I/O error occurs. 426 * @exception NullPointerException If {@code b} is {@code null}. 427 */ 428 public int read(byte[] b) throws IOException { 429 return readBytes(b, 0, b.length); 430 } 431 432 /** 433 * Reads {@code b.length} bytes from this file into the byte 434 * array, starting at the current file pointer. This method reads 435 * repeatedly from the file until the requested number of bytes are 436 * read. This method blocks until the requested number of bytes are 437 * read, the end of the stream is detected, or an exception is thrown. 438 * 439 * @param b the buffer into which the data is read. 440 * @throws NullPointerException if {@code b} is {@code null}. 441 * @throws EOFException if this file reaches the end before reading 442 * all the bytes. 443 * @throws IOException if an I/O error occurs. 444 */ 445 public final void readFully(byte[] b) throws IOException { 446 readFully(b, 0, b.length); 447 } 448 449 /** 450 * Reads exactly {@code len} bytes from this file into the byte 451 * array, starting at the current file pointer. This method reads 452 * repeatedly from the file until the requested number of bytes are 453 * read. This method blocks until the requested number of bytes are 454 * read, the end of the stream is detected, or an exception is thrown. 455 * 456 * @param b the buffer into which the data is read. 457 * @param off the start offset into the data array {@code b}. 458 * @param len the number of bytes to read. 459 * @throws NullPointerException if {@code b} is {@code null}. 460 * @throws IndexOutOfBoundsException if {@code off} is negative, 461 * {@code len} is negative, or {@code len} is greater than 462 * {@code b.length - off}. 463 * @throws EOFException if this file reaches the end before reading 464 * all the bytes. 465 * @throws IOException if an I/O error occurs. 466 */ 467 public final void readFully(byte[] b, int off, int len) throws IOException { 468 int n = 0; 469 do { 470 int count = this.read(b, off + n, len - n); 471 if (count < 0) 472 throw new EOFException(); 473 n += count; 474 } while (n < len); 475 } 476 477 /** 478 * Attempts to skip over {@code n} bytes of input discarding the 479 * skipped bytes. 480 * <p> 481 * 482 * This method may skip over some smaller number of bytes, possibly zero. 483 * This may result from any of a number of conditions; reaching end of 484 * file before {@code n} bytes have been skipped is only one 485 * possibility. This method never throws an {@code EOFException}. 486 * The actual number of bytes skipped is returned. If {@code n} 487 * is negative, no bytes are skipped. 488 * 489 * @param n the number of bytes to be skipped. 490 * @return the actual number of bytes skipped. 491 * @exception IOException if an I/O error occurs. 492 */ 493 public int skipBytes(int n) throws IOException { 494 long pos; 495 long len; 496 long newpos; 497 498 if (n <= 0) { 499 return 0; 500 } 501 pos = getFilePointer(); 502 len = length(); 503 newpos = pos + n; 504 if (newpos > len) { 505 newpos = len; 506 } 507 seek(newpos); 508 509 /* return the actual number of bytes skipped */ 510 return (int) (newpos - pos); 511 } 512 513 // 'Write' primitives 514 515 /** 516 * Writes the specified byte to this file. The write starts at 517 * the current file pointer. 518 * 519 * @param b the {@code byte} to be written. 520 * @exception IOException if an I/O error occurs. 521 */ 522 public void write(int b) throws IOException { 523 write0(b); 524 } 525 526 private native void write0(int b) throws IOException; 527 528 /** 529 * Writes a sub array as a sequence of bytes. 530 * @param b the data to be written 531 532 * @param off the start offset in the data 533 * @param len the number of bytes that are written 534 * @exception IOException If an I/O error has occurred. 535 */ 536 private native void writeBytes(byte[] b, int off, int len) throws IOException; 537 538 /** 539 * Writes {@code b.length} bytes from the specified byte array 540 * to this file, starting at the current file pointer. 541 * 542 * @param b the data. 543 * @exception IOException if an I/O error occurs. 544 */ 545 public void write(byte[] b) throws IOException { 546 writeBytes(b, 0, b.length); 547 } 548 549 /** 550 * Writes {@code len} bytes from the specified byte array 551 * starting at offset {@code off} to this file. 552 * 553 * @param b the data. 554 * @param off the start offset in the data. 555 * @param len the number of bytes to write. 556 * @exception IOException if an I/O error occurs. 557 */ 558 public void write(byte[] b, int off, int len) throws IOException { 559 writeBytes(b, off, len); 560 } 561 562 // 'Random access' stuff 563 564 /** 565 * Returns the current offset in this file. 566 * 567 * @return the offset from the beginning of the file, in bytes, 568 * at which the next read or write occurs. 569 * @exception IOException if an I/O error occurs. 570 */ 571 public native long getFilePointer() throws IOException; 572 573 /** 574 * Sets the file-pointer offset, measured from the beginning of this 575 * file, at which the next read or write occurs. The offset may be 576 * set beyond the end of the file. Setting the offset beyond the end 577 * of the file does not change the file length. The file length will 578 * change only by writing after the offset has been set beyond the end 579 * of the file. 580 * 581 * @param pos the offset position, measured in bytes from the 582 * beginning of the file, at which to set the file 583 * pointer. 584 * @exception IOException if {@code pos} is less than 585 * {@code 0} or if an I/O error occurs. 586 */ 587 public void seek(long pos) throws IOException { 588 if (pos < 0) { 589 throw new IOException("Negative seek offset"); 590 } else { 591 seek0(pos); 592 } 593 } 594 595 private native void seek0(long pos) throws IOException; 596 597 /** 598 * Returns the length of this file. 599 * 600 * @return the length of this file, measured in bytes. 601 * @exception IOException if an I/O error occurs. 602 */ 603 public native long length() throws IOException; 604 605 /** 606 * Sets the length of this file. 607 * 608 * <p> If the present length of the file as returned by the 609 * {@code length} method is greater than the {@code newLength} 610 * argument then the file will be truncated. In this case, if the file 611 * offset as returned by the {@code getFilePointer} method is greater 612 * than {@code newLength} then after this method returns the offset 613 * will be equal to {@code newLength}. 614 * 615 * <p> If the present length of the file as returned by the 616 * {@code length} method is smaller than the {@code newLength} 617 * argument then the file will be extended. In this case, the contents of 618 * the extended portion of the file are not defined. 619 * 620 * @param newLength The desired length of the file 621 * @exception IOException If an I/O error occurs 622 * @since 1.2 623 */ 624 public native void setLength(long newLength) throws IOException; 625 626 /** 627 * Closes this random access file stream and releases any system 628 * resources associated with the stream. A closed random access 629 * file cannot perform input or output operations and cannot be 630 * reopened. 631 * 632 * <p> If this file has an associated channel then the channel is closed 633 * as well. 634 * 635 * @exception IOException if an I/O error occurs. 636 * 637 * @revised 1.4 638 * @spec JSR-51 639 */ 640 public void close() throws IOException { 641 if (!closed.compareAndSet(false, true)) { 642 // if compareAndSet() returns false closed was already true 643 return; 644 } 645 646 FileChannel fc = channel; 647 if (fc != null) { 648 fc.close(); 649 } 650 651 fd.closeAll(new Closeable() { 652 public void close() throws IOException { 653 fd.close(); 654 } 655 }); 656 } 657 658 // 659 // Some "reading/writing Java data types" methods stolen from 660 // DataInputStream and DataOutputStream. 661 // 662 663 /** 664 * Reads a {@code boolean} from this file. This method reads a 665 * single byte from the file, starting at the current file pointer. 666 * A value of {@code 0} represents 667 * {@code false}. Any other value represents {@code true}. 668 * This method blocks until the byte is read, the end of the stream 669 * is detected, or an exception is thrown. 670 * 671 * @return the {@code boolean} value read. 672 * @exception EOFException if this file has reached the end. 673 * @exception IOException if an I/O error occurs. 674 */ 675 public final boolean readBoolean() throws IOException { 676 int ch = this.read(); 677 if (ch < 0) 678 throw new EOFException(); 679 return (ch != 0); 680 } 681 682 /** 683 * Reads a signed eight-bit value from this file. This method reads a 684 * byte from the file, starting from the current file pointer. 685 * If the byte read is {@code b}, where 686 * <code>0 <= b <= 255</code>, 687 * then the result is: 688 * <blockquote><pre> 689 * (byte)(b) 690 * </pre></blockquote> 691 * <p> 692 * This method blocks until the byte is read, the end of the stream 693 * is detected, or an exception is thrown. 694 * 695 * @return the next byte of this file as a signed eight-bit 696 * {@code byte}. 697 * @exception EOFException if this file has reached the end. 698 * @exception IOException if an I/O error occurs. 699 */ 700 public final byte readByte() throws IOException { 701 int ch = this.read(); 702 if (ch < 0) 703 throw new EOFException(); 704 return (byte)(ch); 705 } 706 707 /** 708 * Reads an unsigned eight-bit number from this file. This method reads 709 * a byte from this file, starting at the current file pointer, 710 * and returns that byte. 711 * <p> 712 * This method blocks until the byte is read, the end of the stream 713 * is detected, or an exception is thrown. 714 * 715 * @return the next byte of this file, interpreted as an unsigned 716 * eight-bit number. 717 * @exception EOFException if this file has reached the end. 718 * @exception IOException if an I/O error occurs. 719 */ 720 public final int readUnsignedByte() throws IOException { 721 int ch = this.read(); 722 if (ch < 0) 723 throw new EOFException(); 724 return ch; 725 } 726 727 /** 728 * Reads a signed 16-bit number from this file. The method reads two 729 * bytes from this file, starting at the current file pointer. 730 * If the two bytes read, in order, are 731 * {@code b1} and {@code b2}, where each of the two values is 732 * between {@code 0} and {@code 255}, inclusive, then the 733 * result is equal to: 734 * <blockquote><pre> 735 * (short)((b1 << 8) | b2) 736 * </pre></blockquote> 737 * <p> 738 * This method blocks until the two bytes are read, the end of the 739 * stream is detected, or an exception is thrown. 740 * 741 * @return the next two bytes of this file, interpreted as a signed 742 * 16-bit number. 743 * @exception EOFException if this file reaches the end before reading 744 * two bytes. 745 * @exception IOException if an I/O error occurs. 746 */ 747 public final short readShort() throws IOException { 748 int ch1 = this.read(); 749 int ch2 = this.read(); 750 if ((ch1 | ch2) < 0) 751 throw new EOFException(); 752 return (short)((ch1 << 8) + (ch2 << 0)); 753 } 754 755 /** 756 * Reads an unsigned 16-bit number from this file. This method reads 757 * two bytes from the file, starting at the current file pointer. 758 * If the bytes read, in order, are 759 * {@code b1} and {@code b2}, where 760 * <code>0 <= b1, b2 <= 255</code>, 761 * then the result is equal to: 762 * <blockquote><pre> 763 * (b1 << 8) | b2 764 * </pre></blockquote> 765 * <p> 766 * This method blocks until the two bytes are read, the end of the 767 * stream is detected, or an exception is thrown. 768 * 769 * @return the next two bytes of this file, interpreted as an unsigned 770 * 16-bit integer. 771 * @exception EOFException if this file reaches the end before reading 772 * two bytes. 773 * @exception IOException if an I/O error occurs. 774 */ 775 public final int readUnsignedShort() throws IOException { 776 int ch1 = this.read(); 777 int ch2 = this.read(); 778 if ((ch1 | ch2) < 0) 779 throw new EOFException(); 780 return (ch1 << 8) + (ch2 << 0); 781 } 782 783 /** 784 * Reads a character from this file. This method reads two 785 * bytes from the file, starting at the current file pointer. 786 * If the bytes read, in order, are 787 * {@code b1} and {@code b2}, where 788 * <code>0 <= b1, b2 <= 255</code>, 789 * then the result is equal to: 790 * <blockquote><pre> 791 * (char)((b1 << 8) | b2) 792 * </pre></blockquote> 793 * <p> 794 * This method blocks until the two bytes are read, the end of the 795 * stream is detected, or an exception is thrown. 796 * 797 * @return the next two bytes of this file, interpreted as a 798 * {@code char}. 799 * @exception EOFException if this file reaches the end before reading 800 * two bytes. 801 * @exception IOException if an I/O error occurs. 802 */ 803 public final char readChar() throws IOException { 804 int ch1 = this.read(); 805 int ch2 = this.read(); 806 if ((ch1 | ch2) < 0) 807 throw new EOFException(); 808 return (char)((ch1 << 8) + (ch2 << 0)); 809 } 810 811 /** 812 * Reads a signed 32-bit integer from this file. This method reads 4 813 * bytes from the file, starting at the current file pointer. 814 * If the bytes read, in order, are {@code b1}, 815 * {@code b2}, {@code b3}, and {@code b4}, where 816 * <code>0 <= b1, b2, b3, b4 <= 255</code>, 817 * then the result is equal to: 818 * <blockquote><pre> 819 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4 820 * </pre></blockquote> 821 * <p> 822 * This method blocks until the four bytes are read, the end of the 823 * stream is detected, or an exception is thrown. 824 * 825 * @return the next four bytes of this file, interpreted as an 826 * {@code int}. 827 * @exception EOFException if this file reaches the end before reading 828 * four bytes. 829 * @exception IOException if an I/O error occurs. 830 */ 831 public final int readInt() throws IOException { 832 int ch1 = this.read(); 833 int ch2 = this.read(); 834 int ch3 = this.read(); 835 int ch4 = this.read(); 836 if ((ch1 | ch2 | ch3 | ch4) < 0) 837 throw new EOFException(); 838 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); 839 } 840 841 /** 842 * Reads a signed 64-bit integer from this file. This method reads eight 843 * bytes from the file, starting at the current file pointer. 844 * If the bytes read, in order, are 845 * {@code b1}, {@code b2}, {@code b3}, 846 * {@code b4}, {@code b5}, {@code b6}, 847 * {@code b7}, and {@code b8,} where: 848 * <blockquote><pre> 849 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255, 850 * </pre></blockquote> 851 * <p> 852 * then the result is equal to: 853 * <blockquote><pre> 854 * ((long)b1 << 56) + ((long)b2 << 48) 855 * + ((long)b3 << 40) + ((long)b4 << 32) 856 * + ((long)b5 << 24) + ((long)b6 << 16) 857 * + ((long)b7 << 8) + b8 858 * </pre></blockquote> 859 * <p> 860 * This method blocks until the eight bytes are read, the end of the 861 * stream is detected, or an exception is thrown. 862 * 863 * @return the next eight bytes of this file, interpreted as a 864 * {@code long}. 865 * @exception EOFException if this file reaches the end before reading 866 * eight bytes. 867 * @exception IOException if an I/O error occurs. 868 */ 869 public final long readLong() throws IOException { 870 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL); 871 } 872 873 /** 874 * Reads a {@code float} from this file. This method reads an 875 * {@code int} value, starting at the current file pointer, 876 * as if by the {@code readInt} method 877 * and then converts that {@code int} to a {@code float} 878 * using the {@code intBitsToFloat} method in class 879 * {@code Float}. 880 * <p> 881 * This method blocks until the four bytes are read, the end of the 882 * stream is detected, or an exception is thrown. 883 * 884 * @return the next four bytes of this file, interpreted as a 885 * {@code float}. 886 * @exception EOFException if this file reaches the end before reading 887 * four bytes. 888 * @exception IOException if an I/O error occurs. 889 * @see java.io.RandomAccessFile#readInt() 890 * @see java.lang.Float#intBitsToFloat(int) 891 */ 892 public final float readFloat() throws IOException { 893 return Float.intBitsToFloat(readInt()); 894 } 895 896 /** 897 * Reads a {@code double} from this file. This method reads a 898 * {@code long} value, starting at the current file pointer, 899 * as if by the {@code readLong} method 900 * and then converts that {@code long} to a {@code double} 901 * using the {@code longBitsToDouble} method in 902 * class {@code Double}. 903 * <p> 904 * This method blocks until the eight bytes are read, the end of the 905 * stream is detected, or an exception is thrown. 906 * 907 * @return the next eight bytes of this file, interpreted as a 908 * {@code double}. 909 * @exception EOFException if this file reaches the end before reading 910 * eight bytes. 911 * @exception IOException if an I/O error occurs. 912 * @see java.io.RandomAccessFile#readLong() 913 * @see java.lang.Double#longBitsToDouble(long) 914 */ 915 public final double readDouble() throws IOException { 916 return Double.longBitsToDouble(readLong()); 917 } 918 919 /** 920 * Reads the next line of text from this file. This method successively 921 * reads bytes from the file, starting at the current file pointer, 922 * until it reaches a line terminator or the end 923 * of the file. Each byte is converted into a character by taking the 924 * byte's value for the lower eight bits of the character and setting the 925 * high eight bits of the character to zero. This method does not, 926 * therefore, support the full Unicode character set. 927 * 928 * <p> A line of text is terminated by a carriage-return character 929 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a 930 * carriage-return character immediately followed by a newline character, 931 * or the end of the file. Line-terminating characters are discarded and 932 * are not included as part of the string returned. 933 * 934 * <p> This method blocks until a newline character is read, a carriage 935 * return and the byte following it are read (to see if it is a newline), 936 * the end of the file is reached, or an exception is thrown. 937 * 938 * @return the next line of text from this file, or null if end 939 * of file is encountered before even one byte is read. 940 * @exception IOException if an I/O error occurs. 941 */ 942 943 public final String readLine() throws IOException { 944 StringBuilder input = new StringBuilder(); 945 int c = -1; 946 boolean eol = false; 947 948 while (!eol) { 949 switch (c = read()) { 950 case -1: 951 case '\n': 952 eol = true; 953 break; 954 case '\r': 955 eol = true; 956 long cur = getFilePointer(); 957 if ((read()) != '\n') { 958 seek(cur); 959 } 960 break; 961 default: 962 input.append((char)c); 963 break; 964 } 965 } 966 967 if ((c == -1) && (input.length() == 0)) { 968 return null; 969 } 970 return input.toString(); 971 } 972 973 /** 974 * Reads in a string from this file. The string has been encoded 975 * using a 976 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 977 * format. 978 * <p> 979 * The first two bytes are read, starting from the current file 980 * pointer, as if by 981 * {@code readUnsignedShort}. This value gives the number of 982 * following bytes that are in the encoded string, not 983 * the length of the resulting string. The following bytes are then 984 * interpreted as bytes encoding characters in the modified UTF-8 format 985 * and are converted into characters. 986 * <p> 987 * This method blocks until all the bytes are read, the end of the 988 * stream is detected, or an exception is thrown. 989 * 990 * @return a Unicode string. 991 * @exception EOFException if this file reaches the end before 992 * reading all the bytes. 993 * @exception IOException if an I/O error occurs. 994 * @exception UTFDataFormatException if the bytes do not represent 995 * valid modified UTF-8 encoding of a Unicode string. 996 * @see java.io.RandomAccessFile#readUnsignedShort() 997 */ 998 public final String readUTF() throws IOException { 999 return DataInputStream.readUTF(this); 1000 } 1001 1002 /** 1003 * Writes a {@code boolean} to the file as a one-byte value. The 1004 * value {@code true} is written out as the value 1005 * {@code (byte)1}; the value {@code false} is written out 1006 * as the value {@code (byte)0}. The write starts at 1007 * the current position of the file pointer. 1008 * 1009 * @param v a {@code boolean} value to be written. 1010 * @exception IOException if an I/O error occurs. 1011 */ 1012 public final void writeBoolean(boolean v) throws IOException { 1013 write(v ? 1 : 0); 1014 //written++; 1015 } 1016 1017 /** 1018 * Writes a {@code byte} to the file as a one-byte value. The 1019 * write starts at the current position of the file pointer. 1020 * 1021 * @param v a {@code byte} value to be written. 1022 * @exception IOException if an I/O error occurs. 1023 */ 1024 public final void writeByte(int v) throws IOException { 1025 write(v); 1026 //written++; 1027 } 1028 1029 /** 1030 * Writes a {@code short} to the file as two bytes, high byte first. 1031 * The write starts at the current position of the file pointer. 1032 * 1033 * @param v a {@code short} to be written. 1034 * @exception IOException if an I/O error occurs. 1035 */ 1036 public final void writeShort(int v) throws IOException { 1037 write((v >>> 8) & 0xFF); 1038 write((v >>> 0) & 0xFF); 1039 //written += 2; 1040 } 1041 1042 /** 1043 * Writes a {@code char} to the file as a two-byte value, high 1044 * byte first. The write starts at the current position of the 1045 * file pointer. 1046 * 1047 * @param v a {@code char} value to be written. 1048 * @exception IOException if an I/O error occurs. 1049 */ 1050 public final void writeChar(int v) throws IOException { 1051 write((v >>> 8) & 0xFF); 1052 write((v >>> 0) & 0xFF); 1053 //written += 2; 1054 } 1055 1056 /** 1057 * Writes an {@code int} to the file as four bytes, high byte first. 1058 * The write starts at the current position of the file pointer. 1059 * 1060 * @param v an {@code int} to be written. 1061 * @exception IOException if an I/O error occurs. 1062 */ 1063 public final void writeInt(int v) throws IOException { 1064 write((v >>> 24) & 0xFF); 1065 write((v >>> 16) & 0xFF); 1066 write((v >>> 8) & 0xFF); 1067 write((v >>> 0) & 0xFF); 1068 //written += 4; 1069 } 1070 1071 /** 1072 * Writes a {@code long} to the file as eight bytes, high byte first. 1073 * The write starts at the current position of the file pointer. 1074 * 1075 * @param v a {@code long} to be written. 1076 * @exception IOException if an I/O error occurs. 1077 */ 1078 public final void writeLong(long v) throws IOException { 1079 write((int)(v >>> 56) & 0xFF); 1080 write((int)(v >>> 48) & 0xFF); 1081 write((int)(v >>> 40) & 0xFF); 1082 write((int)(v >>> 32) & 0xFF); 1083 write((int)(v >>> 24) & 0xFF); 1084 write((int)(v >>> 16) & 0xFF); 1085 write((int)(v >>> 8) & 0xFF); 1086 write((int)(v >>> 0) & 0xFF); 1087 //written += 8; 1088 } 1089 1090 /** 1091 * Converts the float argument to an {@code int} using the 1092 * {@code floatToIntBits} method in class {@code Float}, 1093 * and then writes that {@code int} value to the file as a 1094 * four-byte quantity, high byte first. The write starts at the 1095 * current position of the file pointer. 1096 * 1097 * @param v a {@code float} value to be written. 1098 * @exception IOException if an I/O error occurs. 1099 * @see java.lang.Float#floatToIntBits(float) 1100 */ 1101 public final void writeFloat(float v) throws IOException { 1102 writeInt(Float.floatToIntBits(v)); 1103 } 1104 1105 /** 1106 * Converts the double argument to a {@code long} using the 1107 * {@code doubleToLongBits} method in class {@code Double}, 1108 * and then writes that {@code long} value to the file as an 1109 * eight-byte quantity, high byte first. The write starts at the current 1110 * position of the file pointer. 1111 * 1112 * @param v a {@code double} value to be written. 1113 * @exception IOException if an I/O error occurs. 1114 * @see java.lang.Double#doubleToLongBits(double) 1115 */ 1116 public final void writeDouble(double v) throws IOException { 1117 writeLong(Double.doubleToLongBits(v)); 1118 } 1119 1120 /** 1121 * Writes the string to the file as a sequence of bytes. Each 1122 * character in the string is written out, in sequence, by discarding 1123 * its high eight bits. The write starts at the current position of 1124 * the file pointer. 1125 * 1126 * @param s a string of bytes to be written. 1127 * @exception IOException if an I/O error occurs. 1128 */ 1129 @SuppressWarnings("deprecation") 1130 public final void writeBytes(String s) throws IOException { 1131 int len = s.length(); 1132 byte[] b = new byte[len]; 1133 s.getBytes(0, len, b, 0); 1134 writeBytes(b, 0, len); 1135 } 1136 1137 /** 1138 * Writes a string to the file as a sequence of characters. Each 1139 * character is written to the data output stream as if by the 1140 * {@code writeChar} method. The write starts at the current 1141 * position of the file pointer. 1142 * 1143 * @param s a {@code String} value to be written. 1144 * @exception IOException if an I/O error occurs. 1145 * @see java.io.RandomAccessFile#writeChar(int) 1146 */ 1147 public final void writeChars(String s) throws IOException { 1148 int clen = s.length(); 1149 int blen = 2*clen; 1150 byte[] b = new byte[blen]; 1151 char[] c = new char[clen]; 1152 s.getChars(0, clen, c, 0); 1153 for (int i = 0, j = 0; i < clen; i++) { 1154 b[j++] = (byte)(c[i] >>> 8); 1155 b[j++] = (byte)(c[i] >>> 0); 1156 } 1157 writeBytes(b, 0, blen); 1158 } 1159 1160 /** 1161 * Writes a string to the file using 1162 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 1163 * encoding in a machine-independent manner. 1164 * <p> 1165 * First, two bytes are written to the file, starting at the 1166 * current file pointer, as if by the 1167 * {@code writeShort} method giving the number of bytes to 1168 * follow. This value is the number of bytes actually written out, 1169 * not the length of the string. Following the length, each character 1170 * of the string is output, in sequence, using the modified UTF-8 encoding 1171 * for each character. 1172 * 1173 * @param str a string to be written. 1174 * @exception IOException if an I/O error occurs. 1175 */ 1176 public final void writeUTF(String str) throws IOException { 1177 DataOutputStream.writeUTF(str, this); 1178 } 1179 1180 private static native void initIDs(); 1181 1182 static { 1183 initIDs(); 1184 SharedSecrets.setJavaIORandomAccessFileAccess(new JavaIORandomAccessFileAccess() 1185 { 1186 // This is for j.u.z.ZipFile.OPEN_DELETE. The O_TEMPORARY flag 1187 // is only implemented/supported on windows. 1188 public RandomAccessFile openAndDelete(File file, String mode) 1189 throws IOException 1190 { 1191 return new RandomAccessFile(file, mode, true); 1192 } 1193 }); 1194 } 1195 }