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 Object closeLock = new Object(); 75 76 private volatile boolean closed; 77 78 private static final int O_RDONLY = 1; 79 private static final int O_RDWR = 2; 80 private static final int O_SYNC = 4; 81 private static final int O_DSYNC = 8; 82 private static final int O_TEMPORARY = 16; 83 84 /** 85 * Creates a random access file stream to read from, and optionally 86 * to write to, a file with the specified name. A new 87 * {@link FileDescriptor} object is created to represent the 88 * connection to the file. 89 * 90 * <p> The {@code mode} argument specifies the access mode with which the 91 * file is to be opened. The permitted values and their meanings are as 92 * specified for the <a 93 * href="#mode">{@code RandomAccessFile(File,String)}</a> constructor. 94 * 95 * <p> 96 * If there is a security manager, its {@code checkRead} method 97 * is called with the {@code name} argument 98 * as its argument to see if read access to the file is allowed. 99 * If the mode allows writing, the security manager's 100 * {@code checkWrite} method 101 * is also called with the {@code name} argument 102 * as its argument to see if write access to the file is allowed. 103 * 104 * @param name the system-dependent filename 105 * @param mode the access <a href="#mode">mode</a> 106 * @exception IllegalArgumentException if the mode argument is not equal 107 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or 108 * {@code "rwd"} 109 * @exception FileNotFoundException 110 * if the mode is {@code "r"} but the given string does not 111 * denote an existing regular file, or if the mode begins with 112 * {@code "rw"} but the given string does not denote an 113 * existing, writable regular file and a new regular file of 114 * that name cannot be created, or if some other error occurs 115 * while opening or creating the file 116 * @exception SecurityException if a security manager exists and its 117 * {@code checkRead} method denies read access to the file 118 * or the mode is {@code "rw"} and the security manager's 119 * {@code checkWrite} method denies write access to the file 120 * @see java.lang.SecurityException 121 * @see java.lang.SecurityManager#checkRead(java.lang.String) 122 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 123 * @revised 1.4 124 * @spec JSR-51 125 */ 126 public RandomAccessFile(String name, String mode) 127 throws FileNotFoundException 128 { 129 this(name != null ? new File(name) : null, mode); 130 } 131 132 /** 133 * Creates a random access file stream to read from, and optionally to 134 * write to, the file specified by the {@link File} argument. A new {@link 135 * FileDescriptor} object is created to represent this file connection. 136 * 137 * <p>The <a id="mode">{@code mode}</a> argument specifies the access mode 138 * in which the file is to be opened. The permitted values and their 139 * meanings are: 140 * 141 * <table class="striped"> 142 * <caption style="display:none">Access mode permitted values and meanings</caption> 143 * <thead> 144 * <tr><th scope="col" style="text-align:left">Value</th><th scope="col" style="text-align:left">Meaning</th></tr> 145 * </thead> 146 * <tbody> 147 * <tr><th scope="row" style="vertical-align:top">{@code "r"}</th> 148 * <td> Open for reading only. Invoking any of the {@code write} 149 * methods of the resulting object will cause an 150 * {@link java.io.IOException} to be thrown.</td></tr> 151 * <tr><th scope="row" style="vertical-align:top">{@code "rw"}</th> 152 * <td> Open for reading and writing. If the file does not already 153 * exist then an attempt will be made to create it.</td></tr> 154 * <tr><th scope="row" style="vertical-align:top">{@code "rws"}</th> 155 * <td> Open for reading and writing, as with {@code "rw"}, and also 156 * require that every update to the file's content or metadata be 157 * written synchronously to the underlying storage device.</td></tr> 158 * <tr><th scope="row" style="vertical-align:top">{@code "rwd"}</th> 159 * <td> Open for reading and writing, as with {@code "rw"}, and also 160 * require that every update to the file's content be written 161 * synchronously to the underlying storage device.</td></tr> 162 * </tbody> 163 * </table> 164 * 165 * The {@code "rws"} and {@code "rwd"} modes work much like the {@link 166 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of 167 * the {@link java.nio.channels.FileChannel} class, passing arguments of 168 * {@code true} and {@code false}, respectively, except that they always 169 * apply to every I/O operation and are therefore often more efficient. If 170 * the file resides on a local storage device then when an invocation of a 171 * method of this class returns it is guaranteed that all changes made to 172 * the file by that invocation will have been written to that device. This 173 * is useful for ensuring that critical information is not lost in the 174 * event of a system crash. If the file does not reside on a local device 175 * then no such guarantee is made. 176 * 177 * <p>The {@code "rwd"} mode can be used to reduce the number of I/O 178 * operations performed. Using {@code "rwd"} only requires updates to the 179 * file's content to be written to storage; using {@code "rws"} requires 180 * updates to both the file's content and its metadata to be written, which 181 * generally requires at least one more low-level I/O operation. 182 * 183 * <p>If there is a security manager, its {@code checkRead} method is 184 * called with the pathname of the {@code file} argument as its 185 * argument to see if read access to the file is allowed. If the mode 186 * allows writing, the security manager's {@code checkWrite} method is 187 * also called with the path argument to see if write access to the file is 188 * allowed. 189 * 190 * @param file the file object 191 * @param mode the access mode, as described 192 * <a href="#mode">above</a> 193 * @exception IllegalArgumentException if the mode argument is not equal 194 * to one of {@code "r"}, {@code "rw"}, {@code "rws"}, or 195 * {@code "rwd"} 196 * @exception FileNotFoundException 197 * if the mode is {@code "r"} but the given file object does 198 * not denote an existing regular file, or if the mode begins 199 * with {@code "rw"} but the given file object does not denote 200 * an existing, writable regular file and a new regular file of 201 * that name cannot be created, or if some other error occurs 202 * while opening or creating the file 203 * @exception SecurityException if a security manager exists and its 204 * {@code checkRead} method denies read access to the file 205 * or the mode is {@code "rw"} and the security manager's 206 * {@code checkWrite} method denies write access to the file 207 * @see java.lang.SecurityManager#checkRead(java.lang.String) 208 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 209 * @see java.nio.channels.FileChannel#force(boolean) 210 * @revised 1.4 211 * @spec JSR-51 212 */ 213 public RandomAccessFile(File file, String mode) 214 throws FileNotFoundException 215 { 216 this(file, mode, false); 217 } 218 219 private RandomAccessFile(File file, String mode, boolean openAndDelete) 220 throws FileNotFoundException 221 { 222 String name = (file != null ? file.getPath() : null); 223 int imode = -1; 224 if (mode.equals("r")) 225 imode = O_RDONLY; 226 else if (mode.startsWith("rw")) { 227 imode = O_RDWR; 228 rw = true; 229 if (mode.length() > 2) { 230 if (mode.equals("rws")) 231 imode |= O_SYNC; 232 else if (mode.equals("rwd")) 233 imode |= O_DSYNC; 234 else 235 imode = -1; 236 } 237 } 238 if (openAndDelete) 239 imode |= O_TEMPORARY; 240 if (imode < 0) 241 throw new IllegalArgumentException("Illegal mode \"" + mode 242 + "\" must be one of " 243 + "\"r\", \"rw\", \"rws\"," 244 + " or \"rwd\""); 245 SecurityManager security = System.getSecurityManager(); 246 if (security != null) { 247 security.checkRead(name); 248 if (rw) { 249 security.checkWrite(name); 250 } 251 } 252 if (name == null) { 253 throw new NullPointerException(); 254 } 255 if (file.isInvalid()) { 256 throw new FileNotFoundException("Invalid file path"); 257 } 258 fd = new FileDescriptor(); 259 fd.attach(this); 260 path = name; 261 open(name, imode); 262 FileCleanable.register(fd); // open sets the fd, register the cleanup 263 } 264 265 /** 266 * Returns the opaque file descriptor object associated with this 267 * stream. 268 * 269 * @return the file descriptor object associated with this stream. 270 * @exception IOException if an I/O error occurs. 271 * @see java.io.FileDescriptor 272 */ 273 public final FileDescriptor getFD() throws IOException { 274 if (fd != null) { 275 return fd; 276 } 277 throw new IOException(); 278 } 279 280 /** 281 * Returns the unique {@link java.nio.channels.FileChannel FileChannel} 282 * object associated with this file. 283 * 284 * <p> The {@link java.nio.channels.FileChannel#position() 285 * position} of the returned channel will always be equal to 286 * this object's file-pointer offset as returned by the {@link 287 * #getFilePointer getFilePointer} method. Changing this object's 288 * file-pointer offset, whether explicitly or by reading or writing bytes, 289 * will change the position of the channel, and vice versa. Changing the 290 * file's length via this object will change the length seen via the file 291 * channel, and vice versa. 292 * 293 * @return the file channel associated with this file 294 * 295 * @since 1.4 296 * @spec JSR-51 297 */ 298 public final FileChannel getChannel() { 299 FileChannel fc = this.channel; 300 if (fc == null) { 301 synchronized (this) { 302 fc = this.channel; 303 if (fc == null) { 304 this.channel = fc = FileChannelImpl.open(fd, path, true, 305 rw, false, this); 306 if (closed) { 307 try { 308 fc.close(); 309 } catch (IOException ioe) { 310 throw new InternalError(ioe); // should not happen 311 } 312 } 313 } 314 } 315 } 316 return fc; 317 } 318 319 /** 320 * Opens a file and returns the file descriptor. The file is 321 * opened in read-write mode if the O_RDWR bit in {@code mode} 322 * is true, else the file is opened as read-only. 323 * If the {@code name} refers to a directory, an IOException 324 * is thrown. 325 * 326 * @param name the name of the file 327 * @param mode the mode flags, a combination of the O_ constants 328 * defined above 329 */ 330 private native void open0(String name, int mode) 331 throws FileNotFoundException; 332 333 // wrap native call to allow instrumentation 334 /** 335 * Opens a file and returns the file descriptor. The file is 336 * opened in read-write mode if the O_RDWR bit in {@code mode} 337 * is true, else the file is opened as read-only. 338 * If the {@code name} refers to a directory, an IOException 339 * is thrown. 340 * 341 * @param name the name of the file 342 * @param mode the mode flags, a combination of the O_ constants 343 * defined above 344 */ 345 private void open(String name, int mode) 346 throws FileNotFoundException { 347 open0(name, mode); 348 } 349 350 // 'Read' primitives 351 352 /** 353 * Reads a byte of data from this file. The byte is returned as an 354 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This 355 * method blocks if no input is yet available. 356 * <p> 357 * Although {@code RandomAccessFile} is not a subclass of 358 * {@code InputStream}, this method behaves in exactly the same 359 * way as the {@link InputStream#read()} method of 360 * {@code InputStream}. 361 * 362 * @return the next byte of data, or {@code -1} if the end of the 363 * file has been reached. 364 * @exception IOException if an I/O error occurs. Not thrown if 365 * end-of-file has been reached. 366 */ 367 public int read() throws IOException { 368 return read0(); 369 } 370 371 private native int read0() throws IOException; 372 373 /** 374 * Reads a sub array as a sequence of bytes. 375 * @param b the buffer into which the data is read. 376 * @param off the start offset of the data. 377 * @param len the number of bytes to read. 378 * @exception IOException If an I/O error has occurred. 379 */ 380 private native int readBytes(byte b[], int off, int len) throws IOException; 381 382 /** 383 * Reads up to {@code len} bytes of data from this file into an 384 * array of bytes. This method blocks until at least one byte of input 385 * is available. 386 * <p> 387 * Although {@code RandomAccessFile} is not a subclass of 388 * {@code InputStream}, this method behaves in exactly the 389 * same way as the {@link InputStream#read(byte[], int, int)} method of 390 * {@code InputStream}. 391 * 392 * @param b the buffer into which the data is read. 393 * @param off the start offset in array {@code b} 394 * at which the data is written. 395 * @param len the maximum number of bytes read. 396 * @return the total number of bytes read into the buffer, or 397 * {@code -1} if there is no more data because the end of 398 * the file has been reached. 399 * @exception IOException If the first byte cannot be read for any reason 400 * other than end of file, or if the random access file has been closed, or if 401 * some other I/O error occurs. 402 * @exception NullPointerException If {@code b} is {@code null}. 403 * @exception IndexOutOfBoundsException If {@code off} is negative, 404 * {@code len} is negative, or {@code len} is greater than 405 * {@code b.length - off} 406 */ 407 public int read(byte b[], int off, int len) throws IOException { 408 return readBytes(b, off, len); 409 } 410 411 /** 412 * Reads up to {@code b.length} bytes of data from this file 413 * into an array of bytes. This method blocks until at least one byte 414 * of input is available. 415 * <p> 416 * Although {@code RandomAccessFile} is not a subclass of 417 * {@code InputStream}, this method behaves in exactly the 418 * same way as the {@link InputStream#read(byte[])} method of 419 * {@code InputStream}. 420 * 421 * @param b the buffer into which the data is read. 422 * @return the total number of bytes read into the buffer, or 423 * {@code -1} if there is no more data because the end of 424 * this file has been reached. 425 * @exception IOException If the first byte cannot be read for any reason 426 * other than end of file, or if the random access file has been closed, or if 427 * some other I/O error occurs. 428 * @exception NullPointerException If {@code b} is {@code null}. 429 */ 430 public int read(byte b[]) throws IOException { 431 return readBytes(b, 0, b.length); 432 } 433 434 /** 435 * Reads {@code b.length} bytes from this file into the byte 436 * array, starting at the current file pointer. This method reads 437 * repeatedly from the file until the requested number of bytes are 438 * read. This method blocks until the requested number of bytes are 439 * read, the end of the stream is detected, or an exception is thrown. 440 * 441 * @param b the buffer into which the data is read. 442 * @throws NullPointerException if {@code b} is {@code null}. 443 * @throws EOFException if this file reaches the end before reading 444 * all the bytes. 445 * @throws IOException if an I/O error occurs. 446 */ 447 public final void readFully(byte b[]) throws IOException { 448 readFully(b, 0, b.length); 449 } 450 451 /** 452 * Reads exactly {@code len} bytes from this file into the byte 453 * array, starting at the current file pointer. This method reads 454 * repeatedly from the file until the requested number of bytes are 455 * read. This method blocks until the requested number of bytes are 456 * read, the end of the stream is detected, or an exception is thrown. 457 * 458 * @param b the buffer into which the data is read. 459 * @param off the start offset into the data array {@code b}. 460 * @param len the number of bytes to read. 461 * @throws NullPointerException if {@code b} is {@code null}. 462 * @throws IndexOutOfBoundsException if {@code off} is negative, 463 * {@code len} is negative, or {@code len} is greater than 464 * {@code b.length - off}. 465 * @throws EOFException if this file reaches the end before reading 466 * all the bytes. 467 * @throws IOException if an I/O error occurs. 468 */ 469 public final void readFully(byte b[], int off, int len) throws IOException { 470 int n = 0; 471 do { 472 int count = this.read(b, off + n, len - n); 473 if (count < 0) 474 throw new EOFException(); 475 n += count; 476 } while (n < len); 477 } 478 479 /** 480 * Attempts to skip over {@code n} bytes of input discarding the 481 * skipped bytes. 482 * <p> 483 * 484 * This method may skip over some smaller number of bytes, possibly zero. 485 * This may result from any of a number of conditions; reaching end of 486 * file before {@code n} bytes have been skipped is only one 487 * possibility. This method never throws an {@code EOFException}. 488 * The actual number of bytes skipped is returned. If {@code n} 489 * is negative, no bytes are skipped. 490 * 491 * @param n the number of bytes to be skipped. 492 * @return the actual number of bytes skipped. 493 * @exception IOException if an I/O error occurs. 494 */ 495 public int skipBytes(int n) throws IOException { 496 long pos; 497 long len; 498 long newpos; 499 500 if (n <= 0) { 501 return 0; 502 } 503 pos = getFilePointer(); 504 len = length(); 505 newpos = pos + n; 506 if (newpos > len) { 507 newpos = len; 508 } 509 seek(newpos); 510 511 /* return the actual number of bytes skipped */ 512 return (int) (newpos - pos); 513 } 514 515 // 'Write' primitives 516 517 /** 518 * Writes the specified byte to this file. The write starts at 519 * the current file pointer. 520 * 521 * @param b the {@code byte} to be written. 522 * @exception IOException if an I/O error occurs. 523 */ 524 public void write(int b) throws IOException { 525 write0(b); 526 } 527 528 private native void write0(int b) throws IOException; 529 530 /** 531 * Writes a sub array as a sequence of bytes. 532 * @param b the data to be written 533 534 * @param off the start offset in the data 535 * @param len the number of bytes that are written 536 * @exception IOException If an I/O error has occurred. 537 */ 538 private native void writeBytes(byte b[], int off, int len) throws IOException; 539 540 /** 541 * Writes {@code b.length} bytes from the specified byte array 542 * to this file, starting at the current file pointer. 543 * 544 * @param b the data. 545 * @exception IOException if an I/O error occurs. 546 */ 547 public void write(byte b[]) throws IOException { 548 writeBytes(b, 0, b.length); 549 } 550 551 /** 552 * Writes {@code len} bytes from the specified byte array 553 * starting at offset {@code off} to this file. 554 * 555 * @param b the data. 556 * @param off the start offset in the data. 557 * @param len the number of bytes to write. 558 * @exception IOException if an I/O error occurs. 559 */ 560 public void write(byte b[], int off, int len) throws IOException { 561 writeBytes(b, off, len); 562 } 563 564 // 'Random access' stuff 565 566 /** 567 * Returns the current offset in this file. 568 * 569 * @return the offset from the beginning of the file, in bytes, 570 * at which the next read or write occurs. 571 * @exception IOException if an I/O error occurs. 572 */ 573 public native long getFilePointer() throws IOException; 574 575 /** 576 * Sets the file-pointer offset, measured from the beginning of this 577 * file, at which the next read or write occurs. The offset may be 578 * set beyond the end of the file. Setting the offset beyond the end 579 * of the file does not change the file length. The file length will 580 * change only by writing after the offset has been set beyond the end 581 * of the file. 582 * 583 * @param pos the offset position, measured in bytes from the 584 * beginning of the file, at which to set the file 585 * pointer. 586 * @exception IOException if {@code pos} is less than 587 * {@code 0} or if an I/O error occurs. 588 */ 589 public void seek(long pos) throws IOException { 590 if (pos < 0) { 591 throw new IOException("Negative seek offset"); 592 } else { 593 seek0(pos); 594 } 595 } 596 597 private native void seek0(long pos) throws IOException; 598 599 /** 600 * Returns the length of this file. 601 * 602 * @return the length of this file, measured in bytes. 603 * @exception IOException if an I/O error occurs. 604 */ 605 public native long length() throws IOException; 606 607 /** 608 * Sets the length of this file. 609 * 610 * <p> If the present length of the file as returned by the 611 * {@code length} method is greater than the {@code newLength} 612 * argument then the file will be truncated. In this case, if the file 613 * offset as returned by the {@code getFilePointer} method is greater 614 * than {@code newLength} then after this method returns the offset 615 * will be equal to {@code newLength}. 616 * 617 * <p> If the present length of the file as returned by the 618 * {@code length} method is smaller than the {@code newLength} 619 * argument then the file will be extended. In this case, the contents of 620 * the extended portion of the file are not defined. 621 * 622 * @param newLength The desired length of the file 623 * @exception IOException If an I/O error occurs 624 * @since 1.2 625 */ 626 public native void setLength(long newLength) throws IOException; 627 628 /** 629 * Closes this random access file stream and releases any system 630 * resources associated with the stream. A closed random access 631 * file cannot perform input or output operations and cannot be 632 * reopened. 633 * 634 * <p> If this file has an associated channel then the channel is closed 635 * as well. 636 * 637 * @exception IOException if an I/O error occurs. 638 * 639 * @revised 1.4 640 * @spec JSR-51 641 */ 642 public void close() throws IOException { 643 if (closed) { 644 return; 645 } 646 synchronized (closeLock) { 647 if (closed) { 648 return; 649 } 650 closed = true; 651 } 652 653 FileChannel fc = channel; 654 if (fc != null) { 655 // possible race with getChannel(), benign since 656 // FileChannel.close is final and idempotent 657 fc.close(); 658 } 659 660 fd.closeAll(new Closeable() { 661 public void close() throws IOException { 662 fd.close(); 663 } 664 }); 665 } 666 667 // 668 // Some "reading/writing Java data types" methods stolen from 669 // DataInputStream and DataOutputStream. 670 // 671 672 /** 673 * Reads a {@code boolean} from this file. This method reads a 674 * single byte from the file, starting at the current file pointer. 675 * A value of {@code 0} represents 676 * {@code false}. Any other value represents {@code true}. 677 * This method blocks until the byte is read, the end of the stream 678 * is detected, or an exception is thrown. 679 * 680 * @return the {@code boolean} value read. 681 * @exception EOFException if this file has reached the end. 682 * @exception IOException if an I/O error occurs. 683 */ 684 public final boolean readBoolean() throws IOException { 685 int ch = this.read(); 686 if (ch < 0) 687 throw new EOFException(); 688 return (ch != 0); 689 } 690 691 /** 692 * Reads a signed eight-bit value from this file. This method reads a 693 * byte from the file, starting from the current file pointer. 694 * If the byte read is {@code b}, where 695 * <code>0 <= b <= 255</code>, 696 * then the result is: 697 * <blockquote><pre> 698 * (byte)(b) 699 * </pre></blockquote> 700 * <p> 701 * This method blocks until the byte is read, the end of the stream 702 * is detected, or an exception is thrown. 703 * 704 * @return the next byte of this file as a signed eight-bit 705 * {@code byte}. 706 * @exception EOFException if this file has reached the end. 707 * @exception IOException if an I/O error occurs. 708 */ 709 public final byte readByte() throws IOException { 710 int ch = this.read(); 711 if (ch < 0) 712 throw new EOFException(); 713 return (byte)(ch); 714 } 715 716 /** 717 * Reads an unsigned eight-bit number from this file. This method reads 718 * a byte from this file, starting at the current file pointer, 719 * and returns that byte. 720 * <p> 721 * This method blocks until the byte is read, the end of the stream 722 * is detected, or an exception is thrown. 723 * 724 * @return the next byte of this file, interpreted as an unsigned 725 * eight-bit number. 726 * @exception EOFException if this file has reached the end. 727 * @exception IOException if an I/O error occurs. 728 */ 729 public final int readUnsignedByte() throws IOException { 730 int ch = this.read(); 731 if (ch < 0) 732 throw new EOFException(); 733 return ch; 734 } 735 736 /** 737 * Reads a signed 16-bit number from this file. The method reads two 738 * bytes from this file, starting at the current file pointer. 739 * If the two bytes read, in order, are 740 * {@code b1} and {@code b2}, where each of the two values is 741 * between {@code 0} and {@code 255}, inclusive, then the 742 * result is equal to: 743 * <blockquote><pre> 744 * (short)((b1 << 8) | b2) 745 * </pre></blockquote> 746 * <p> 747 * This method blocks until the two bytes are read, the end of the 748 * stream is detected, or an exception is thrown. 749 * 750 * @return the next two bytes of this file, interpreted as a signed 751 * 16-bit number. 752 * @exception EOFException if this file reaches the end before reading 753 * two bytes. 754 * @exception IOException if an I/O error occurs. 755 */ 756 public final short readShort() throws IOException { 757 int ch1 = this.read(); 758 int ch2 = this.read(); 759 if ((ch1 | ch2) < 0) 760 throw new EOFException(); 761 return (short)((ch1 << 8) + (ch2 << 0)); 762 } 763 764 /** 765 * Reads an unsigned 16-bit number from this file. This method reads 766 * two bytes from the file, starting at the current file pointer. 767 * If the bytes read, in order, are 768 * {@code b1} and {@code b2}, where 769 * <code>0 <= b1, b2 <= 255</code>, 770 * then the result is equal to: 771 * <blockquote><pre> 772 * (b1 << 8) | b2 773 * </pre></blockquote> 774 * <p> 775 * This method blocks until the two bytes are read, the end of the 776 * stream is detected, or an exception is thrown. 777 * 778 * @return the next two bytes of this file, interpreted as an unsigned 779 * 16-bit integer. 780 * @exception EOFException if this file reaches the end before reading 781 * two bytes. 782 * @exception IOException if an I/O error occurs. 783 */ 784 public final int readUnsignedShort() throws IOException { 785 int ch1 = this.read(); 786 int ch2 = this.read(); 787 if ((ch1 | ch2) < 0) 788 throw new EOFException(); 789 return (ch1 << 8) + (ch2 << 0); 790 } 791 792 /** 793 * Reads a character from this file. This method reads two 794 * bytes from the file, starting at the current file pointer. 795 * If the bytes read, in order, are 796 * {@code b1} and {@code b2}, where 797 * <code>0 <= b1, b2 <= 255</code>, 798 * then the result is equal to: 799 * <blockquote><pre> 800 * (char)((b1 << 8) | b2) 801 * </pre></blockquote> 802 * <p> 803 * This method blocks until the two bytes are read, the end of the 804 * stream is detected, or an exception is thrown. 805 * 806 * @return the next two bytes of this file, interpreted as a 807 * {@code char}. 808 * @exception EOFException if this file reaches the end before reading 809 * two bytes. 810 * @exception IOException if an I/O error occurs. 811 */ 812 public final char readChar() throws IOException { 813 int ch1 = this.read(); 814 int ch2 = this.read(); 815 if ((ch1 | ch2) < 0) 816 throw new EOFException(); 817 return (char)((ch1 << 8) + (ch2 << 0)); 818 } 819 820 /** 821 * Reads a signed 32-bit integer from this file. This method reads 4 822 * bytes from the file, starting at the current file pointer. 823 * If the bytes read, in order, are {@code b1}, 824 * {@code b2}, {@code b3}, and {@code b4}, where 825 * <code>0 <= b1, b2, b3, b4 <= 255</code>, 826 * then the result is equal to: 827 * <blockquote><pre> 828 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4 829 * </pre></blockquote> 830 * <p> 831 * This method blocks until the four bytes are read, the end of the 832 * stream is detected, or an exception is thrown. 833 * 834 * @return the next four bytes of this file, interpreted as an 835 * {@code int}. 836 * @exception EOFException if this file reaches the end before reading 837 * four bytes. 838 * @exception IOException if an I/O error occurs. 839 */ 840 public final int readInt() throws IOException { 841 int ch1 = this.read(); 842 int ch2 = this.read(); 843 int ch3 = this.read(); 844 int ch4 = this.read(); 845 if ((ch1 | ch2 | ch3 | ch4) < 0) 846 throw new EOFException(); 847 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); 848 } 849 850 /** 851 * Reads a signed 64-bit integer from this file. This method reads eight 852 * bytes from the file, starting at the current file pointer. 853 * If the bytes read, in order, are 854 * {@code b1}, {@code b2}, {@code b3}, 855 * {@code b4}, {@code b5}, {@code b6}, 856 * {@code b7}, and {@code b8,} where: 857 * <blockquote><pre> 858 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255, 859 * </pre></blockquote> 860 * <p> 861 * then the result is equal to: 862 * <blockquote><pre> 863 * ((long)b1 << 56) + ((long)b2 << 48) 864 * + ((long)b3 << 40) + ((long)b4 << 32) 865 * + ((long)b5 << 24) + ((long)b6 << 16) 866 * + ((long)b7 << 8) + b8 867 * </pre></blockquote> 868 * <p> 869 * This method blocks until the eight bytes are read, the end of the 870 * stream is detected, or an exception is thrown. 871 * 872 * @return the next eight bytes of this file, interpreted as a 873 * {@code long}. 874 * @exception EOFException if this file reaches the end before reading 875 * eight bytes. 876 * @exception IOException if an I/O error occurs. 877 */ 878 public final long readLong() throws IOException { 879 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL); 880 } 881 882 /** 883 * Reads a {@code float} from this file. This method reads an 884 * {@code int} value, starting at the current file pointer, 885 * as if by the {@code readInt} method 886 * and then converts that {@code int} to a {@code float} 887 * using the {@code intBitsToFloat} method in class 888 * {@code Float}. 889 * <p> 890 * This method blocks until the four bytes are read, the end of the 891 * stream is detected, or an exception is thrown. 892 * 893 * @return the next four bytes of this file, interpreted as a 894 * {@code float}. 895 * @exception EOFException if this file reaches the end before reading 896 * four bytes. 897 * @exception IOException if an I/O error occurs. 898 * @see java.io.RandomAccessFile#readInt() 899 * @see java.lang.Float#intBitsToFloat(int) 900 */ 901 public final float readFloat() throws IOException { 902 return Float.intBitsToFloat(readInt()); 903 } 904 905 /** 906 * Reads a {@code double} from this file. This method reads a 907 * {@code long} value, starting at the current file pointer, 908 * as if by the {@code readLong} method 909 * and then converts that {@code long} to a {@code double} 910 * using the {@code longBitsToDouble} method in 911 * class {@code Double}. 912 * <p> 913 * This method blocks until the eight bytes are read, the end of the 914 * stream is detected, or an exception is thrown. 915 * 916 * @return the next eight bytes of this file, interpreted as a 917 * {@code double}. 918 * @exception EOFException if this file reaches the end before reading 919 * eight bytes. 920 * @exception IOException if an I/O error occurs. 921 * @see java.io.RandomAccessFile#readLong() 922 * @see java.lang.Double#longBitsToDouble(long) 923 */ 924 public final double readDouble() throws IOException { 925 return Double.longBitsToDouble(readLong()); 926 } 927 928 /** 929 * Reads the next line of text from this file. This method successively 930 * reads bytes from the file, starting at the current file pointer, 931 * until it reaches a line terminator or the end 932 * of the file. Each byte is converted into a character by taking the 933 * byte's value for the lower eight bits of the character and setting the 934 * high eight bits of the character to zero. This method does not, 935 * therefore, support the full Unicode character set. 936 * 937 * <p> A line of text is terminated by a carriage-return character 938 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a 939 * carriage-return character immediately followed by a newline character, 940 * or the end of the file. Line-terminating characters are discarded and 941 * are not included as part of the string returned. 942 * 943 * <p> This method blocks until a newline character is read, a carriage 944 * return and the byte following it are read (to see if it is a newline), 945 * the end of the file is reached, or an exception is thrown. 946 * 947 * @return the next line of text from this file, or null if end 948 * of file is encountered before even one byte is read. 949 * @exception IOException if an I/O error occurs. 950 */ 951 952 public final String readLine() throws IOException { 953 StringBuilder input = new StringBuilder(); 954 int c = -1; 955 boolean eol = false; 956 957 while (!eol) { 958 switch (c = read()) { 959 case -1: 960 case '\n': 961 eol = true; 962 break; 963 case '\r': 964 eol = true; 965 long cur = getFilePointer(); 966 if ((read()) != '\n') { 967 seek(cur); 968 } 969 break; 970 default: 971 input.append((char)c); 972 break; 973 } 974 } 975 976 if ((c == -1) && (input.length() == 0)) { 977 return null; 978 } 979 return input.toString(); 980 } 981 982 /** 983 * Reads in a string from this file. The string has been encoded 984 * using a 985 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 986 * format. 987 * <p> 988 * The first two bytes are read, starting from the current file 989 * pointer, as if by 990 * {@code readUnsignedShort}. This value gives the number of 991 * following bytes that are in the encoded string, not 992 * the length of the resulting string. The following bytes are then 993 * interpreted as bytes encoding characters in the modified UTF-8 format 994 * and are converted into characters. 995 * <p> 996 * This method blocks until all the bytes are read, the end of the 997 * stream is detected, or an exception is thrown. 998 * 999 * @return a Unicode string. 1000 * @exception EOFException if this file reaches the end before 1001 * reading all the bytes. 1002 * @exception IOException if an I/O error occurs. 1003 * @exception UTFDataFormatException if the bytes do not represent 1004 * valid modified UTF-8 encoding of a Unicode string. 1005 * @see java.io.RandomAccessFile#readUnsignedShort() 1006 */ 1007 public final String readUTF() throws IOException { 1008 return DataInputStream.readUTF(this); 1009 } 1010 1011 /** 1012 * Writes a {@code boolean} to the file as a one-byte value. The 1013 * value {@code true} is written out as the value 1014 * {@code (byte)1}; the value {@code false} is written out 1015 * as the value {@code (byte)0}. The write starts at 1016 * the current position of the file pointer. 1017 * 1018 * @param v a {@code boolean} value to be written. 1019 * @exception IOException if an I/O error occurs. 1020 */ 1021 public final void writeBoolean(boolean v) throws IOException { 1022 write(v ? 1 : 0); 1023 //written++; 1024 } 1025 1026 /** 1027 * Writes a {@code byte} to the file as a one-byte value. The 1028 * write starts at the current position of the file pointer. 1029 * 1030 * @param v a {@code byte} value to be written. 1031 * @exception IOException if an I/O error occurs. 1032 */ 1033 public final void writeByte(int v) throws IOException { 1034 write(v); 1035 //written++; 1036 } 1037 1038 /** 1039 * Writes a {@code short} to the file as two bytes, high byte first. 1040 * The write starts at the current position of the file pointer. 1041 * 1042 * @param v a {@code short} to be written. 1043 * @exception IOException if an I/O error occurs. 1044 */ 1045 public final void writeShort(int v) throws IOException { 1046 write((v >>> 8) & 0xFF); 1047 write((v >>> 0) & 0xFF); 1048 //written += 2; 1049 } 1050 1051 /** 1052 * Writes a {@code char} to the file as a two-byte value, high 1053 * byte first. The write starts at the current position of the 1054 * file pointer. 1055 * 1056 * @param v a {@code char} value to be written. 1057 * @exception IOException if an I/O error occurs. 1058 */ 1059 public final void writeChar(int v) throws IOException { 1060 write((v >>> 8) & 0xFF); 1061 write((v >>> 0) & 0xFF); 1062 //written += 2; 1063 } 1064 1065 /** 1066 * Writes an {@code int} to the file as four bytes, high byte first. 1067 * The write starts at the current position of the file pointer. 1068 * 1069 * @param v an {@code int} to be written. 1070 * @exception IOException if an I/O error occurs. 1071 */ 1072 public final void writeInt(int v) throws IOException { 1073 write((v >>> 24) & 0xFF); 1074 write((v >>> 16) & 0xFF); 1075 write((v >>> 8) & 0xFF); 1076 write((v >>> 0) & 0xFF); 1077 //written += 4; 1078 } 1079 1080 /** 1081 * Writes a {@code long} to the file as eight bytes, high byte first. 1082 * The write starts at the current position of the file pointer. 1083 * 1084 * @param v a {@code long} to be written. 1085 * @exception IOException if an I/O error occurs. 1086 */ 1087 public final void writeLong(long v) throws IOException { 1088 write((int)(v >>> 56) & 0xFF); 1089 write((int)(v >>> 48) & 0xFF); 1090 write((int)(v >>> 40) & 0xFF); 1091 write((int)(v >>> 32) & 0xFF); 1092 write((int)(v >>> 24) & 0xFF); 1093 write((int)(v >>> 16) & 0xFF); 1094 write((int)(v >>> 8) & 0xFF); 1095 write((int)(v >>> 0) & 0xFF); 1096 //written += 8; 1097 } 1098 1099 /** 1100 * Converts the float argument to an {@code int} using the 1101 * {@code floatToIntBits} method in class {@code Float}, 1102 * and then writes that {@code int} value to the file as a 1103 * four-byte quantity, high byte first. The write starts at the 1104 * current position of the file pointer. 1105 * 1106 * @param v a {@code float} value to be written. 1107 * @exception IOException if an I/O error occurs. 1108 * @see java.lang.Float#floatToIntBits(float) 1109 */ 1110 public final void writeFloat(float v) throws IOException { 1111 writeInt(Float.floatToIntBits(v)); 1112 } 1113 1114 /** 1115 * Converts the double argument to a {@code long} using the 1116 * {@code doubleToLongBits} method in class {@code Double}, 1117 * and then writes that {@code long} value to the file as an 1118 * eight-byte quantity, high byte first. The write starts at the current 1119 * position of the file pointer. 1120 * 1121 * @param v a {@code double} value to be written. 1122 * @exception IOException if an I/O error occurs. 1123 * @see java.lang.Double#doubleToLongBits(double) 1124 */ 1125 public final void writeDouble(double v) throws IOException { 1126 writeLong(Double.doubleToLongBits(v)); 1127 } 1128 1129 /** 1130 * Writes the string to the file as a sequence of bytes. Each 1131 * character in the string is written out, in sequence, by discarding 1132 * its high eight bits. The write starts at the current position of 1133 * the file pointer. 1134 * 1135 * @param s a string of bytes to be written. 1136 * @exception IOException if an I/O error occurs. 1137 */ 1138 @SuppressWarnings("deprecation") 1139 public final void writeBytes(String s) throws IOException { 1140 int len = s.length(); 1141 byte[] b = new byte[len]; 1142 s.getBytes(0, len, b, 0); 1143 writeBytes(b, 0, len); 1144 } 1145 1146 /** 1147 * Writes a string to the file as a sequence of characters. Each 1148 * character is written to the data output stream as if by the 1149 * {@code writeChar} method. The write starts at the current 1150 * position of the file pointer. 1151 * 1152 * @param s a {@code String} value to be written. 1153 * @exception IOException if an I/O error occurs. 1154 * @see java.io.RandomAccessFile#writeChar(int) 1155 */ 1156 public final void writeChars(String s) throws IOException { 1157 int clen = s.length(); 1158 int blen = 2*clen; 1159 byte[] b = new byte[blen]; 1160 char[] c = new char[clen]; 1161 s.getChars(0, clen, c, 0); 1162 for (int i = 0, j = 0; i < clen; i++) { 1163 b[j++] = (byte)(c[i] >>> 8); 1164 b[j++] = (byte)(c[i] >>> 0); 1165 } 1166 writeBytes(b, 0, blen); 1167 } 1168 1169 /** 1170 * Writes a string to the file using 1171 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 1172 * encoding in a machine-independent manner. 1173 * <p> 1174 * First, two bytes are written to the file, starting at the 1175 * current file pointer, as if by the 1176 * {@code writeShort} method giving the number of bytes to 1177 * follow. This value is the number of bytes actually written out, 1178 * not the length of the string. Following the length, each character 1179 * of the string is output, in sequence, using the modified UTF-8 encoding 1180 * for each character. 1181 * 1182 * @param str a string to be written. 1183 * @exception IOException if an I/O error occurs. 1184 */ 1185 public final void writeUTF(String str) throws IOException { 1186 DataOutputStream.writeUTF(str, this); 1187 } 1188 1189 private static native void initIDs(); 1190 1191 static { 1192 initIDs(); 1193 SharedSecrets.setJavaIORandomAccessFileAccess(new JavaIORandomAccessFileAccess() 1194 { 1195 // This is for j.u.z.ZipFile.OPEN_DELETE. The O_TEMPORARY flag 1196 // is only implemented/supported on windows. 1197 public RandomAccessFile openAndDelete(File file, String mode) 1198 throws IOException 1199 { 1200 return new RandomAccessFile(file, mode, true); 1201 } 1202 }); 1203 } 1204 }