1 /* 2 * Copyright (c) 1994, 2016, 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 name="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 summary="Access mode permitted values and meanings"> 140 * <tr><th align="left">Value</th><th align="left">Meaning</th></tr> 141 * <tr><td valign="top">{@code "r"}</td> 142 * <td> Open for reading only. Invoking any of the {@code write} 143 * methods of the resulting object will cause an 144 * {@link java.io.IOException} to be thrown.</td></tr> 145 * <tr><td valign="top">{@code "rw"}</td> 146 * <td> Open for reading and writing. If the file does not already 147 * exist then an attempt will be made to create it.</td></tr> 148 * <tr><td valign="top">{@code "rws"}</td> 149 * <td> Open for reading and writing, as with {@code "rw"}, and also 150 * require that every update to the file's content or metadata be 151 * written synchronously to the underlying storage device.</td></tr> 152 * <tr><td valign="top">{@code "rwd"}</td> 153 * <td> Open for reading and writing, as with {@code "rw"}, and also 154 * require that every update to the file's content be written 155 * synchronously to the underlying storage device.</td></tr> 156 * </table> 157 * 158 * The {@code "rws"} and {@code "rwd"} modes work much like the {@link 159 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of 160 * the {@link java.nio.channels.FileChannel} class, passing arguments of 161 * {@code true} and {@code false}, respectively, except that they always 162 * apply to every I/O operation and are therefore often more efficient. If 163 * the file resides on a local storage device then when an invocation of a 164 * method of this class returns it is guaranteed that all changes made to 165 * the file by that invocation will have been written to that device. This 166 * is useful for ensuring that critical information is not lost in the 167 * event of a system crash. If the file does not reside on a local device 168 * then no such guarantee is made. 169 * 170 * <p>The {@code "rwd"} mode can be used to reduce the number of I/O 171 * operations performed. Using {@code "rwd"} only requires updates to the 172 * file's content to be written to storage; using {@code "rws"} requires 173 * updates to both the file's content and its metadata to be written, which 174 * generally requires at least one more low-level I/O operation. 175 * 176 * <p>If there is a security manager, its {@code checkRead} method is 177 * called with the pathname of the {@code file} argument as its 178 * argument to see if read access to the file is allowed. If the mode 179 * allows writing, the security manager's {@code checkWrite} method is 180 * also called with the path argument to see if write access to the file is 181 * allowed. 182 * 183 * @param file the file object 184 * @param mode the access mode, as described 185 * <a href="#mode">above</a> 186 * @exception IllegalArgumentException if the mode argument is not equal 187 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or 188 * {@code "rwd"} 189 * @exception FileNotFoundException 190 * if the mode is {@code "r"} but the given file object does 191 * not denote an existing regular file, or if the mode begins 192 * with {@code "rw"} but the given file object does not denote 193 * an existing, writable regular file and a new regular file of 194 * that name cannot be created, or if some other error occurs 195 * while opening or creating the file 196 * @exception SecurityException if a security manager exists and its 197 * {@code checkRead} method denies read access to the file 198 * or the mode is {@code "rw"} and the security manager's 199 * {@code checkWrite} method denies write access to the file 200 * @see java.lang.SecurityManager#checkRead(java.lang.String) 201 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 202 * @see java.nio.channels.FileChannel#force(boolean) 203 * @revised 1.4 204 * @spec JSR-51 205 */ 206 public RandomAccessFile(File file, String mode) 207 throws FileNotFoundException 208 { 209 this(file, mode, false); 210 } 211 212 private RandomAccessFile(File file, String mode, boolean openAndDelete) 213 throws FileNotFoundException 214 { 215 String name = (file != null ? file.getPath() : null); 216 int imode = -1; 217 if (mode.equals("r")) 218 imode = O_RDONLY; 219 else if (mode.startsWith("rw")) { 220 imode = O_RDWR; 221 rw = true; 222 if (mode.length() > 2) { 223 if (mode.equals("rws")) 224 imode |= O_SYNC; 225 else if (mode.equals("rwd")) 226 imode |= O_DSYNC; 227 else 228 imode = -1; 229 } 230 } 231 if (openAndDelete) 232 imode |= O_TEMPORARY; 233 if (imode < 0) 234 throw new IllegalArgumentException("Illegal mode \"" + mode 235 + "\" must be one of " 236 + "\"r\", \"rw\", \"rws\"," 237 + " or \"rwd\""); 238 SecurityManager security = System.getSecurityManager(); 239 if (security != null) { 240 security.checkRead(name); 241 if (rw) { 242 security.checkWrite(name); 243 } 244 } 245 if (name == null) { 246 throw new NullPointerException(); 247 } 248 if (file.isInvalid()) { 249 throw new FileNotFoundException("Invalid file path"); 250 } 251 fd = new FileDescriptor(); 252 fd.attach(this); 253 path = name; 254 open(name, imode); 255 } 256 257 /** 258 * Returns the opaque file descriptor object associated with this 259 * stream. 260 * 261 * @return the file descriptor object associated with this stream. 262 * @exception IOException if an I/O error occurs. 263 * @see java.io.FileDescriptor 264 */ 265 public final FileDescriptor getFD() throws IOException { 266 if (fd != null) { 267 return fd; 268 } 269 throw new IOException(); 270 } 271 272 /** 273 * Returns the unique {@link java.nio.channels.FileChannel FileChannel} 274 * object associated with this file. 275 * 276 * <p> The {@link java.nio.channels.FileChannel#position() 277 * position} of the returned channel will always be equal to 278 * this object's file-pointer offset as returned by the {@link 279 * #getFilePointer getFilePointer} method. Changing this object's 280 * file-pointer offset, whether explicitly or by reading or writing bytes, 281 * will change the position of the channel, and vice versa. Changing the 282 * file's length via this object will change the length seen via the file 283 * channel, and vice versa. 284 * 285 * @return the file channel associated with this file 286 * 287 * @since 1.4 288 * @spec JSR-51 289 */ 290 public final FileChannel getChannel() { 291 FileChannel fc = this.channel; 292 if (fc == null) { 293 synchronized (this) { 294 fc = this.channel; 295 if (fc == null) { 296 this.channel = fc = FileChannelImpl.open(fd, path, true, rw, this); 297 if (closed.get()) { 298 try { 299 fc.close(); 300 } catch (IOException ioe) { 301 throw new InternalError(ioe); // should not happen 302 } 303 } 304 } 305 } 306 } 307 return fc; 308 } 309 310 /** 311 * Opens a file and returns the file descriptor. The file is 312 * opened in read-write mode if the O_RDWR bit in {@code mode} 313 * is true, else the file is opened as read-only. 314 * If the {@code name} refers to a directory, an IOException 315 * is thrown. 316 * 317 * @param name the name of the file 318 * @param mode the mode flags, a combination of the O_ constants 319 * defined above 320 */ 321 private native void open0(String name, int mode) 322 throws FileNotFoundException; 323 324 // wrap native call to allow instrumentation 325 /** 326 * Opens a file and returns the file descriptor. The file is 327 * opened in read-write mode if the O_RDWR bit in {@code mode} 328 * is true, else the file is opened as read-only. 329 * If the {@code name} refers to a directory, an IOException 330 * is thrown. 331 * 332 * @param name the name of the file 333 * @param mode the mode flags, a combination of the O_ constants 334 * defined above 335 */ 336 private void open(String name, int mode) 337 throws FileNotFoundException { 338 open0(name, mode); 339 } 340 341 // 'Read' primitives 342 343 /** 344 * Reads a byte of data from this file. The byte is returned as an 345 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This 346 * method blocks if no input is yet available. 347 * <p> 348 * Although {@code RandomAccessFile} is not a subclass of 349 * {@code InputStream}, this method behaves in exactly the same 350 * way as the {@link InputStream#read()} method of 351 * {@code InputStream}. 352 * 353 * @return the next byte of data, or {@code -1} if the end of the 354 * file has been reached. 355 * @exception IOException if an I/O error occurs. Not thrown if 356 * end-of-file has been reached. 357 */ 358 public int read() throws IOException { 359 return read0(); 360 } 361 362 private native int read0() throws IOException; 363 364 /** 365 * Reads a sub array as a sequence of bytes. 366 * @param b the buffer into which the data is read. 367 * @param off the start offset of the data. 368 * @param len the number of bytes to read. 369 * @exception IOException If an I/O error has occurred. 370 */ 371 private native int readBytes(byte b[], int off, int len) throws IOException; 372 373 /** 374 * Reads up to {@code len} bytes of data from this file into an 375 * array of bytes. This method blocks until at least one byte of input 376 * is available. 377 * <p> 378 * Although {@code RandomAccessFile} is not a subclass of 379 * {@code InputStream}, this method behaves in exactly the 380 * same way as the {@link InputStream#read(byte[], int, int)} method of 381 * {@code InputStream}. 382 * 383 * @param b the buffer into which the data is read. 384 * @param off the start offset in array {@code b} 385 * at which the data is written. 386 * @param len the maximum number of bytes read. 387 * @return the total number of bytes read into the buffer, or 388 * {@code -1} if there is no more data because the end of 389 * the file has been reached. 390 * @exception IOException If the first byte cannot be read for any reason 391 * other than end of file, or if the random access file has been closed, or if 392 * some other I/O error occurs. 393 * @exception NullPointerException If {@code b} is {@code null}. 394 * @exception IndexOutOfBoundsException If {@code off} is negative, 395 * {@code len} is negative, or {@code len} is greater than 396 * {@code b.length - off} 397 */ 398 public int read(byte b[], int off, int len) throws IOException { 399 return readBytes(b, off, len); 400 } 401 402 /** 403 * Reads up to {@code b.length} bytes of data from this file 404 * into an array of bytes. This method blocks until at least one byte 405 * of input is available. 406 * <p> 407 * Although {@code RandomAccessFile} is not a subclass of 408 * {@code InputStream}, this method behaves in exactly the 409 * same way as the {@link InputStream#read(byte[])} method of 410 * {@code InputStream}. 411 * 412 * @param b the buffer into which the data is read. 413 * @return the total number of bytes read into the buffer, or 414 * {@code -1} if there is no more data because the end of 415 * this file has been reached. 416 * @exception IOException If the first byte cannot be read for any reason 417 * other than end of file, or if the random access file has been closed, or if 418 * some other I/O error occurs. 419 * @exception NullPointerException If {@code b} is {@code null}. 420 */ 421 public int read(byte b[]) throws IOException { 422 return readBytes(b, 0, b.length); 423 } 424 425 /** 426 * Reads {@code b.length} bytes from this file into the byte 427 * array, starting at the current file pointer. This method reads 428 * repeatedly from the file until the requested number of bytes are 429 * read. This method blocks until the requested number of bytes are 430 * read, the end of the stream is detected, or an exception is thrown. 431 * 432 * @param b the buffer into which the data is read. 433 * @throws NullPointerException if {@code b} is {@code null}. 434 * @throws EOFException if this file reaches the end before reading 435 * all the bytes. 436 * @throws IOException if an I/O error occurs. 437 */ 438 public final void readFully(byte b[]) throws IOException { 439 readFully(b, 0, b.length); 440 } 441 442 /** 443 * Reads exactly {@code len} bytes from this file into the byte 444 * array, starting at the current file pointer. This method reads 445 * repeatedly from the file until the requested number of bytes are 446 * read. This method blocks until the requested number of bytes are 447 * read, the end of the stream is detected, or an exception is thrown. 448 * 449 * @param b the buffer into which the data is read. 450 * @param off the start offset into the data array {@code b}. 451 * @param len the number of bytes to read. 452 * @throws NullPointerException if {@code b} is {@code null}. 453 * @throws IndexOutOfBoundsException if {@code off} is negative, 454 * {@code len} is negative, or {@code len} is greater than 455 * {@code b.length - off}. 456 * @throws EOFException if this file reaches the end before reading 457 * all the bytes. 458 * @throws IOException if an I/O error occurs. 459 */ 460 public final void readFully(byte b[], int off, int len) throws IOException { 461 int n = 0; 462 do { 463 int count = this.read(b, off + n, len - n); 464 if (count < 0) 465 throw new EOFException(); 466 n += count; 467 } while (n < len); 468 } 469 470 /** 471 * Attempts to skip over {@code n} bytes of input discarding the 472 * skipped bytes. 473 * <p> 474 * 475 * This method may skip over some smaller number of bytes, possibly zero. 476 * This may result from any of a number of conditions; reaching end of 477 * file before {@code n} bytes have been skipped is only one 478 * possibility. This method never throws an {@code EOFException}. 479 * The actual number of bytes skipped is returned. If {@code n} 480 * is negative, no bytes are skipped. 481 * 482 * @param n the number of bytes to be skipped. 483 * @return the actual number of bytes skipped. 484 * @exception IOException if an I/O error occurs. 485 */ 486 public int skipBytes(int n) throws IOException { 487 long pos; 488 long len; 489 long newpos; 490 491 if (n <= 0) { 492 return 0; 493 } 494 pos = getFilePointer(); 495 len = length(); 496 newpos = pos + n; 497 if (newpos > len) { 498 newpos = len; 499 } 500 seek(newpos); 501 502 /* return the actual number of bytes skipped */ 503 return (int) (newpos - pos); 504 } 505 506 // 'Write' primitives 507 508 /** 509 * Writes the specified byte to this file. The write starts at 510 * the current file pointer. 511 * 512 * @param b the {@code byte} to be written. 513 * @exception IOException if an I/O error occurs. 514 */ 515 public void write(int b) throws IOException { 516 write0(b); 517 } 518 519 private native void write0(int b) throws IOException; 520 521 /** 522 * Writes a sub array as a sequence of bytes. 523 * @param b the data to be written 524 525 * @param off the start offset in the data 526 * @param len the number of bytes that are written 527 * @exception IOException If an I/O error has occurred. 528 */ 529 private native void writeBytes(byte b[], int off, int len) throws IOException; 530 531 /** 532 * Writes {@code b.length} bytes from the specified byte array 533 * to this file, starting at the current file pointer. 534 * 535 * @param b the data. 536 * @exception IOException if an I/O error occurs. 537 */ 538 public void write(byte b[]) throws IOException { 539 writeBytes(b, 0, b.length); 540 } 541 542 /** 543 * Writes {@code len} bytes from the specified byte array 544 * starting at offset {@code off} to this file. 545 * 546 * @param b the data. 547 * @param off the start offset in the data. 548 * @param len the number of bytes to write. 549 * @exception IOException if an I/O error occurs. 550 */ 551 public void write(byte b[], int off, int len) throws IOException { 552 writeBytes(b, off, len); 553 } 554 555 // 'Random access' stuff 556 557 /** 558 * Returns the current offset in this file. 559 * 560 * @return the offset from the beginning of the file, in bytes, 561 * at which the next read or write occurs. 562 * @exception IOException if an I/O error occurs. 563 */ 564 public native long getFilePointer() throws IOException; 565 566 /** 567 * Sets the file-pointer offset, measured from the beginning of this 568 * file, at which the next read or write occurs. The offset may be 569 * set beyond the end of the file. Setting the offset beyond the end 570 * of the file does not change the file length. The file length will 571 * change only by writing after the offset has been set beyond the end 572 * of the file. 573 * 574 * @param pos the offset position, measured in bytes from the 575 * beginning of the file, at which to set the file 576 * pointer. 577 * @exception IOException if {@code pos} is less than 578 * {@code 0} or if an I/O error occurs. 579 */ 580 public void seek(long pos) throws IOException { 581 if (pos < 0) { 582 throw new IOException("Negative seek offset"); 583 } else { 584 seek0(pos); 585 } 586 } 587 588 private native void seek0(long pos) throws IOException; 589 590 /** 591 * Returns the length of this file. 592 * 593 * @return the length of this file, measured in bytes. 594 * @exception IOException if an I/O error occurs. 595 */ 596 public native long length() throws IOException; 597 598 /** 599 * Sets the length of this file. 600 * 601 * <p> If the present length of the file as returned by the 602 * {@code length} method is greater than the {@code newLength} 603 * argument then the file will be truncated. In this case, if the file 604 * offset as returned by the {@code getFilePointer} method is greater 605 * than {@code newLength} then after this method returns the offset 606 * will be equal to {@code newLength}. 607 * 608 * <p> If the present length of the file as returned by the 609 * {@code length} method is smaller than the {@code newLength} 610 * argument then the file will be extended. In this case, the contents of 611 * the extended portion of the file are not defined. 612 * 613 * @param newLength The desired length of the file 614 * @exception IOException If an I/O error occurs 615 * @since 1.2 616 */ 617 public native void setLength(long newLength) throws IOException; 618 619 /** 620 * Closes this random access file stream and releases any system 621 * resources associated with the stream. A closed random access 622 * file cannot perform input or output operations and cannot be 623 * reopened. 624 * 625 * <p> If this file has an associated channel then the channel is closed 626 * as well. 627 * 628 * @exception IOException if an I/O error occurs. 629 * 630 * @revised 1.4 631 * @spec JSR-51 632 */ 633 public void close() throws IOException { 634 if (!closed.compareAndSet(false, true)) { 635 // if compareAndSet() returns false closed was already true 636 return; 637 } 638 639 FileChannel fc = channel; 640 if (fc != null) { 641 fc.close(); 642 } 643 644 fd.closeAll(new Closeable() { 645 public void close() throws IOException { 646 close0(); 647 } 648 }); 649 } 650 651 // 652 // Some "reading/writing Java data types" methods stolen from 653 // DataInputStream and DataOutputStream. 654 // 655 656 /** 657 * Reads a {@code boolean} from this file. This method reads a 658 * single byte from the file, starting at the current file pointer. 659 * A value of {@code 0} represents 660 * {@code false}. Any other value represents {@code true}. 661 * This method blocks until the byte is read, the end of the stream 662 * is detected, or an exception is thrown. 663 * 664 * @return the {@code boolean} value read. 665 * @exception EOFException if this file has reached the end. 666 * @exception IOException if an I/O error occurs. 667 */ 668 public final boolean readBoolean() throws IOException { 669 int ch = this.read(); 670 if (ch < 0) 671 throw new EOFException(); 672 return (ch != 0); 673 } 674 675 /** 676 * Reads a signed eight-bit value from this file. This method reads a 677 * byte from the file, starting from the current file pointer. 678 * If the byte read is {@code b}, where 679 * <code>0 <= b <= 255</code>, 680 * then the result is: 681 * <blockquote><pre> 682 * (byte)(b) 683 * </pre></blockquote> 684 * <p> 685 * This method blocks until the byte is read, the end of the stream 686 * is detected, or an exception is thrown. 687 * 688 * @return the next byte of this file as a signed eight-bit 689 * {@code byte}. 690 * @exception EOFException if this file has reached the end. 691 * @exception IOException if an I/O error occurs. 692 */ 693 public final byte readByte() throws IOException { 694 int ch = this.read(); 695 if (ch < 0) 696 throw new EOFException(); 697 return (byte)(ch); 698 } 699 700 /** 701 * Reads an unsigned eight-bit number from this file. This method reads 702 * a byte from this file, starting at the current file pointer, 703 * and returns that byte. 704 * <p> 705 * This method blocks until the byte is read, the end of the stream 706 * is detected, or an exception is thrown. 707 * 708 * @return the next byte of this file, interpreted as an unsigned 709 * eight-bit number. 710 * @exception EOFException if this file has reached the end. 711 * @exception IOException if an I/O error occurs. 712 */ 713 public final int readUnsignedByte() throws IOException { 714 int ch = this.read(); 715 if (ch < 0) 716 throw new EOFException(); 717 return ch; 718 } 719 720 /** 721 * Reads a signed 16-bit number from this file. The method reads two 722 * bytes from this file, starting at the current file pointer. 723 * If the two bytes read, in order, are 724 * {@code b1} and {@code b2}, where each of the two values is 725 * between {@code 0} and {@code 255}, inclusive, then the 726 * result is equal to: 727 * <blockquote><pre> 728 * (short)((b1 << 8) | b2) 729 * </pre></blockquote> 730 * <p> 731 * This method blocks until the two bytes are read, the end of the 732 * stream is detected, or an exception is thrown. 733 * 734 * @return the next two bytes of this file, interpreted as a signed 735 * 16-bit number. 736 * @exception EOFException if this file reaches the end before reading 737 * two bytes. 738 * @exception IOException if an I/O error occurs. 739 */ 740 public final short readShort() throws IOException { 741 int ch1 = this.read(); 742 int ch2 = this.read(); 743 if ((ch1 | ch2) < 0) 744 throw new EOFException(); 745 return (short)((ch1 << 8) + (ch2 << 0)); 746 } 747 748 /** 749 * Reads an unsigned 16-bit number from this file. This method reads 750 * two bytes from the file, starting at the current file pointer. 751 * If the bytes read, in order, are 752 * {@code b1} and {@code b2}, where 753 * <code>0 <= b1, b2 <= 255</code>, 754 * then the result is equal to: 755 * <blockquote><pre> 756 * (b1 << 8) | b2 757 * </pre></blockquote> 758 * <p> 759 * This method blocks until the two bytes are read, the end of the 760 * stream is detected, or an exception is thrown. 761 * 762 * @return the next two bytes of this file, interpreted as an unsigned 763 * 16-bit integer. 764 * @exception EOFException if this file reaches the end before reading 765 * two bytes. 766 * @exception IOException if an I/O error occurs. 767 */ 768 public final int readUnsignedShort() throws IOException { 769 int ch1 = this.read(); 770 int ch2 = this.read(); 771 if ((ch1 | ch2) < 0) 772 throw new EOFException(); 773 return (ch1 << 8) + (ch2 << 0); 774 } 775 776 /** 777 * Reads a character from this file. This method reads two 778 * bytes from the file, starting at the current file pointer. 779 * If the bytes read, in order, are 780 * {@code b1} and {@code b2}, where 781 * <code>0 <= b1, b2 <= 255</code>, 782 * then the result is equal to: 783 * <blockquote><pre> 784 * (char)((b1 << 8) | b2) 785 * </pre></blockquote> 786 * <p> 787 * This method blocks until the two bytes are read, the end of the 788 * stream is detected, or an exception is thrown. 789 * 790 * @return the next two bytes of this file, interpreted as a 791 * {@code char}. 792 * @exception EOFException if this file reaches the end before reading 793 * two bytes. 794 * @exception IOException if an I/O error occurs. 795 */ 796 public final char readChar() throws IOException { 797 int ch1 = this.read(); 798 int ch2 = this.read(); 799 if ((ch1 | ch2) < 0) 800 throw new EOFException(); 801 return (char)((ch1 << 8) + (ch2 << 0)); 802 } 803 804 /** 805 * Reads a signed 32-bit integer from this file. This method reads 4 806 * bytes from the file, starting at the current file pointer. 807 * If the bytes read, in order, are {@code b1}, 808 * {@code b2}, {@code b3}, and {@code b4}, where 809 * <code>0 <= b1, b2, b3, b4 <= 255</code>, 810 * then the result is equal to: 811 * <blockquote><pre> 812 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4 813 * </pre></blockquote> 814 * <p> 815 * This method blocks until the four bytes are read, the end of the 816 * stream is detected, or an exception is thrown. 817 * 818 * @return the next four bytes of this file, interpreted as an 819 * {@code int}. 820 * @exception EOFException if this file reaches the end before reading 821 * four bytes. 822 * @exception IOException if an I/O error occurs. 823 */ 824 public final int readInt() throws IOException { 825 int ch1 = this.read(); 826 int ch2 = this.read(); 827 int ch3 = this.read(); 828 int ch4 = this.read(); 829 if ((ch1 | ch2 | ch3 | ch4) < 0) 830 throw new EOFException(); 831 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); 832 } 833 834 /** 835 * Reads a signed 64-bit integer from this file. This method reads eight 836 * bytes from the file, starting at the current file pointer. 837 * If the bytes read, in order, are 838 * {@code b1}, {@code b2}, {@code b3}, 839 * {@code b4}, {@code b5}, {@code b6}, 840 * {@code b7}, and {@code b8,} where: 841 * <blockquote><pre> 842 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255, 843 * </pre></blockquote> 844 * <p> 845 * then the result is equal to: 846 * <blockquote><pre> 847 * ((long)b1 << 56) + ((long)b2 << 48) 848 * + ((long)b3 << 40) + ((long)b4 << 32) 849 * + ((long)b5 << 24) + ((long)b6 << 16) 850 * + ((long)b7 << 8) + b8 851 * </pre></blockquote> 852 * <p> 853 * This method blocks until the eight bytes are read, the end of the 854 * stream is detected, or an exception is thrown. 855 * 856 * @return the next eight bytes of this file, interpreted as a 857 * {@code long}. 858 * @exception EOFException if this file reaches the end before reading 859 * eight bytes. 860 * @exception IOException if an I/O error occurs. 861 */ 862 public final long readLong() throws IOException { 863 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL); 864 } 865 866 /** 867 * Reads a {@code float} from this file. This method reads an 868 * {@code int} value, starting at the current file pointer, 869 * as if by the {@code readInt} method 870 * and then converts that {@code int} to a {@code float} 871 * using the {@code intBitsToFloat} method in class 872 * {@code Float}. 873 * <p> 874 * This method blocks until the four bytes are read, the end of the 875 * stream is detected, or an exception is thrown. 876 * 877 * @return the next four bytes of this file, interpreted as a 878 * {@code float}. 879 * @exception EOFException if this file reaches the end before reading 880 * four bytes. 881 * @exception IOException if an I/O error occurs. 882 * @see java.io.RandomAccessFile#readInt() 883 * @see java.lang.Float#intBitsToFloat(int) 884 */ 885 public final float readFloat() throws IOException { 886 return Float.intBitsToFloat(readInt()); 887 } 888 889 /** 890 * Reads a {@code double} from this file. This method reads a 891 * {@code long} value, starting at the current file pointer, 892 * as if by the {@code readLong} method 893 * and then converts that {@code long} to a {@code double} 894 * using the {@code longBitsToDouble} method in 895 * class {@code Double}. 896 * <p> 897 * This method blocks until the eight bytes are read, the end of the 898 * stream is detected, or an exception is thrown. 899 * 900 * @return the next eight bytes of this file, interpreted as a 901 * {@code double}. 902 * @exception EOFException if this file reaches the end before reading 903 * eight bytes. 904 * @exception IOException if an I/O error occurs. 905 * @see java.io.RandomAccessFile#readLong() 906 * @see java.lang.Double#longBitsToDouble(long) 907 */ 908 public final double readDouble() throws IOException { 909 return Double.longBitsToDouble(readLong()); 910 } 911 912 /** 913 * Reads the next line of text from this file. This method successively 914 * reads bytes from the file, starting at the current file pointer, 915 * until it reaches a line terminator or the end 916 * of the file. Each byte is converted into a character by taking the 917 * byte's value for the lower eight bits of the character and setting the 918 * high eight bits of the character to zero. This method does not, 919 * therefore, support the full Unicode character set. 920 * 921 * <p> A line of text is terminated by a carriage-return character 922 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a 923 * carriage-return character immediately followed by a newline character, 924 * or the end of the file. Line-terminating characters are discarded and 925 * are not included as part of the string returned. 926 * 927 * <p> This method blocks until a newline character is read, a carriage 928 * return and the byte following it are read (to see if it is a newline), 929 * the end of the file is reached, or an exception is thrown. 930 * 931 * @return the next line of text from this file, or null if end 932 * of file is encountered before even one byte is read. 933 * @exception IOException if an I/O error occurs. 934 */ 935 936 public final String readLine() throws IOException { 937 StringBuilder input = new StringBuilder(); 938 int c = -1; 939 boolean eol = false; 940 941 while (!eol) { 942 switch (c = read()) { 943 case -1: 944 case '\n': 945 eol = true; 946 break; 947 case '\r': 948 eol = true; 949 long cur = getFilePointer(); 950 if ((read()) != '\n') { 951 seek(cur); 952 } 953 break; 954 default: 955 input.append((char)c); 956 break; 957 } 958 } 959 960 if ((c == -1) && (input.length() == 0)) { 961 return null; 962 } 963 return input.toString(); 964 } 965 966 /** 967 * Reads in a string from this file. The string has been encoded 968 * using a 969 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 970 * format. 971 * <p> 972 * The first two bytes are read, starting from the current file 973 * pointer, as if by 974 * {@code readUnsignedShort}. This value gives the number of 975 * following bytes that are in the encoded string, not 976 * the length of the resulting string. The following bytes are then 977 * interpreted as bytes encoding characters in the modified UTF-8 format 978 * and are converted into characters. 979 * <p> 980 * This method blocks until all the bytes are read, the end of the 981 * stream is detected, or an exception is thrown. 982 * 983 * @return a Unicode string. 984 * @exception EOFException if this file reaches the end before 985 * reading all the bytes. 986 * @exception IOException if an I/O error occurs. 987 * @exception UTFDataFormatException if the bytes do not represent 988 * valid modified UTF-8 encoding of a Unicode string. 989 * @see java.io.RandomAccessFile#readUnsignedShort() 990 */ 991 public final String readUTF() throws IOException { 992 return DataInputStream.readUTF(this); 993 } 994 995 /** 996 * Writes a {@code boolean} to the file as a one-byte value. The 997 * value {@code true} is written out as the value 998 * {@code (byte)1}; the value {@code false} is written out 999 * as the value {@code (byte)0}. The write starts at 1000 * the current position of the file pointer. 1001 * 1002 * @param v a {@code boolean} value to be written. 1003 * @exception IOException if an I/O error occurs. 1004 */ 1005 public final void writeBoolean(boolean v) throws IOException { 1006 write(v ? 1 : 0); 1007 //written++; 1008 } 1009 1010 /** 1011 * Writes a {@code byte} to the file as a one-byte value. The 1012 * write starts at the current position of the file pointer. 1013 * 1014 * @param v a {@code byte} value to be written. 1015 * @exception IOException if an I/O error occurs. 1016 */ 1017 public final void writeByte(int v) throws IOException { 1018 write(v); 1019 //written++; 1020 } 1021 1022 /** 1023 * Writes a {@code short} to the file as two bytes, high byte first. 1024 * The write starts at the current position of the file pointer. 1025 * 1026 * @param v a {@code short} to be written. 1027 * @exception IOException if an I/O error occurs. 1028 */ 1029 public final void writeShort(int v) throws IOException { 1030 write((v >>> 8) & 0xFF); 1031 write((v >>> 0) & 0xFF); 1032 //written += 2; 1033 } 1034 1035 /** 1036 * Writes a {@code char} to the file as a two-byte value, high 1037 * byte first. The write starts at the current position of the 1038 * file pointer. 1039 * 1040 * @param v a {@code char} value to be written. 1041 * @exception IOException if an I/O error occurs. 1042 */ 1043 public final void writeChar(int v) throws IOException { 1044 write((v >>> 8) & 0xFF); 1045 write((v >>> 0) & 0xFF); 1046 //written += 2; 1047 } 1048 1049 /** 1050 * Writes an {@code int} to the file as four bytes, high byte first. 1051 * The write starts at the current position of the file pointer. 1052 * 1053 * @param v an {@code int} to be written. 1054 * @exception IOException if an I/O error occurs. 1055 */ 1056 public final void writeInt(int v) throws IOException { 1057 write((v >>> 24) & 0xFF); 1058 write((v >>> 16) & 0xFF); 1059 write((v >>> 8) & 0xFF); 1060 write((v >>> 0) & 0xFF); 1061 //written += 4; 1062 } 1063 1064 /** 1065 * Writes a {@code long} to the file as eight bytes, high byte first. 1066 * The write starts at the current position of the file pointer. 1067 * 1068 * @param v a {@code long} to be written. 1069 * @exception IOException if an I/O error occurs. 1070 */ 1071 public final void writeLong(long v) throws IOException { 1072 write((int)(v >>> 56) & 0xFF); 1073 write((int)(v >>> 48) & 0xFF); 1074 write((int)(v >>> 40) & 0xFF); 1075 write((int)(v >>> 32) & 0xFF); 1076 write((int)(v >>> 24) & 0xFF); 1077 write((int)(v >>> 16) & 0xFF); 1078 write((int)(v >>> 8) & 0xFF); 1079 write((int)(v >>> 0) & 0xFF); 1080 //written += 8; 1081 } 1082 1083 /** 1084 * Converts the float argument to an {@code int} using the 1085 * {@code floatToIntBits} method in class {@code Float}, 1086 * and then writes that {@code int} value to the file as a 1087 * four-byte quantity, high byte first. The write starts at the 1088 * current position of the file pointer. 1089 * 1090 * @param v a {@code float} value to be written. 1091 * @exception IOException if an I/O error occurs. 1092 * @see java.lang.Float#floatToIntBits(float) 1093 */ 1094 public final void writeFloat(float v) throws IOException { 1095 writeInt(Float.floatToIntBits(v)); 1096 } 1097 1098 /** 1099 * Converts the double argument to a {@code long} using the 1100 * {@code doubleToLongBits} method in class {@code Double}, 1101 * and then writes that {@code long} value to the file as an 1102 * eight-byte quantity, high byte first. The write starts at the current 1103 * position of the file pointer. 1104 * 1105 * @param v a {@code double} value to be written. 1106 * @exception IOException if an I/O error occurs. 1107 * @see java.lang.Double#doubleToLongBits(double) 1108 */ 1109 public final void writeDouble(double v) throws IOException { 1110 writeLong(Double.doubleToLongBits(v)); 1111 } 1112 1113 /** 1114 * Writes the string to the file as a sequence of bytes. Each 1115 * character in the string is written out, in sequence, by discarding 1116 * its high eight bits. The write starts at the current position of 1117 * the file pointer. 1118 * 1119 * @param s a string of bytes to be written. 1120 * @exception IOException if an I/O error occurs. 1121 */ 1122 @SuppressWarnings("deprecation") 1123 public final void writeBytes(String s) throws IOException { 1124 int len = s.length(); 1125 byte[] b = new byte[len]; 1126 s.getBytes(0, len, b, 0); 1127 writeBytes(b, 0, len); 1128 } 1129 1130 /** 1131 * Writes a string to the file as a sequence of characters. Each 1132 * character is written to the data output stream as if by the 1133 * {@code writeChar} method. The write starts at the current 1134 * position of the file pointer. 1135 * 1136 * @param s a {@code String} value to be written. 1137 * @exception IOException if an I/O error occurs. 1138 * @see java.io.RandomAccessFile#writeChar(int) 1139 */ 1140 public final void writeChars(String s) throws IOException { 1141 int clen = s.length(); 1142 int blen = 2*clen; 1143 byte[] b = new byte[blen]; 1144 char[] c = new char[clen]; 1145 s.getChars(0, clen, c, 0); 1146 for (int i = 0, j = 0; i < clen; i++) { 1147 b[j++] = (byte)(c[i] >>> 8); 1148 b[j++] = (byte)(c[i] >>> 0); 1149 } 1150 writeBytes(b, 0, blen); 1151 } 1152 1153 /** 1154 * Writes a string to the file using 1155 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 1156 * encoding in a machine-independent manner. 1157 * <p> 1158 * First, two bytes are written to the file, starting at the 1159 * current file pointer, as if by the 1160 * {@code writeShort} method giving the number of bytes to 1161 * follow. This value is the number of bytes actually written out, 1162 * not the length of the string. Following the length, each character 1163 * of the string is output, in sequence, using the modified UTF-8 encoding 1164 * for each character. 1165 * 1166 * @param str a string to be written. 1167 * @exception IOException if an I/O error occurs. 1168 */ 1169 public final void writeUTF(String str) throws IOException { 1170 DataOutputStream.writeUTF(str, this); 1171 } 1172 1173 private static native void initIDs(); 1174 1175 private native void close0() throws IOException; 1176 1177 static { 1178 initIDs(); 1179 SharedSecrets.setJavaIORandomAccessFileAccess(new JavaIORandomAccessFileAccess() 1180 { 1181 // This is for j.u.z.ZipFile.OPEN_DELETE. The O_TEMPORARY flag 1182 // is only implemented/supported on windows. 1183 public RandomAccessFile openAndDelete(File file, String mode) 1184 throws IOException 1185 { 1186 return new RandomAccessFile(file, mode, true); 1187 } 1188 }); 1189 } 1190 }