1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. Oracle designates this 9 * particular file as subject to the "Classpath" exception as provided 10 * by Oracle in the LICENSE file that accompanied this code. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 * or visit www.oracle.com if you need additional information or have any 24 * questions. 25 */ 26 27 package java.io; 28 29 import java.nio.channels.FileChannel; 30 import sun.nio.ch.FileChannelImpl; 31 import android.system.ErrnoException; 32 import dalvik.system.CloseGuard; 33 import libcore.io.IoBridge; 34 import libcore.io.IoTracker; 35 import libcore.io.Libcore; 36 import static android.system.OsConstants.*; 37 38 39 /** 40 * Instances of this class support both reading and writing to a 41 * random access file. A random access file behaves like a large 42 * array of bytes stored in the file system. There is a kind of cursor, 43 * or index into the implied array, called the <em>file pointer</em>; 44 * input operations read bytes starting at the file pointer and advance 45 * the file pointer past the bytes read. If the random access file is 46 * created in read/write mode, then output operations are also available; 47 * output operations write bytes starting at the file pointer and advance 48 * the file pointer past the bytes written. Output operations that write 49 * past the current end of the implied array cause the array to be 50 * extended. The file pointer can be read by the 51 * {@code getFilePointer} method and set by the {@code seek} 52 * method. 53 * <p> 54 * It is generally true of all the reading routines in this class that 55 * if end-of-file is reached before the desired number of bytes has been 56 * read, an {@code EOFException} (which is a kind of 57 * {@code IOException}) is thrown. If any byte cannot be read for 58 * any reason other than end-of-file, an {@code IOException} other 59 * than {@code EOFException} is thrown. In particular, an 60 * {@code IOException} may be thrown if the stream has been closed. 61 * 62 * @author unascribed 63 * @since JDK1.0 64 */ 65 66 public class RandomAccessFile implements DataOutput, DataInput, Closeable { 67 68 private final CloseGuard guard = CloseGuard.get(); 69 private final byte[] scratch = new byte[8]; 70 private boolean syncMetadata = false; 71 private int mode; 72 73 private FileDescriptor fd; 74 private FileChannel channel = null; 75 private boolean rw; 76 77 /** 78 * The path of the referenced file 79 * (null if the stream is created with a file descriptor) 80 */ 81 private final String path; 82 83 private Object closeLock = new Object(); 84 private volatile boolean closed = false; 85 /** 86 * A single tracker to track both read and write. The tracker resets when the operation 87 * performed is different from the operation last performed. 88 */ 89 private final IoTracker ioTracker = new IoTracker(); 90 91 /** 92 * Creates a random access file stream to read from, and optionally 93 * to write to, a file with the specified name. A new 94 * {@link FileDescriptor} object is created to represent the 95 * connection to the file. 96 * 97 * <p> The <tt>mode</tt> argument specifies the access mode with which the 98 * file is to be opened. The permitted values and their meanings are as 99 * specified for the <a 100 * href="#mode"><tt>RandomAccessFile(File,String)</tt></a> constructor. 101 * 102 * <p> 103 * If there is a security manager, its {@code checkRead} method 104 * is called with the {@code name} argument 105 * as its argument to see if read access to the file is allowed. 106 * If the mode allows writing, the security manager's 107 * {@code checkWrite} method 108 * is also called with the {@code name} argument 109 * as its argument to see if write access to the file is allowed. 110 * 111 * @param name the system-dependent filename 112 * @param mode the access <a href="#mode">mode</a> 113 * @exception IllegalArgumentException if the mode argument is not equal 114 * to one of <tt>"r"</tt>, <tt>"rw"</tt>, <tt>"rws"</tt>, or 115 * <tt>"rwd"</tt> 116 * @exception FileNotFoundException 117 * if the mode is <tt>"r"</tt> but the given string does not 118 * denote an existing regular file, or if the mode begins with 119 * <tt>"rw"</tt> but the given string does not denote an 120 * existing, writable regular file and a new regular file of 121 * that name cannot be created, or if some other error occurs 122 * while opening or creating the file 123 * @exception SecurityException if a security manager exists and its 124 * {@code checkRead} method denies read access to the file 125 * or the mode is "rw" and the security manager's 126 * {@code checkWrite} method denies write access to the file 127 * @see java.lang.SecurityException 128 * @see java.lang.SecurityManager#checkRead(java.lang.String) 129 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 130 * @revised 1.4 131 * @spec JSR-51 132 */ 133 public RandomAccessFile(String name, String mode) 134 throws FileNotFoundException 135 { 136 this(name != null ? new File(name) : null, mode); 137 } 138 139 /** 140 * Creates a random access file stream to read from, and optionally to 141 * write to, the file specified by the {@link File} argument. A new {@link 142 * FileDescriptor} object is created to represent this file connection. 143 * 144 * <p>The <a name="mode"><tt>mode</tt></a> argument specifies the access mode 145 * in which the file is to be opened. The permitted values and their 146 * meanings are: 147 * 148 * <table summary="Access mode permitted values and meanings"> 149 * <tr><th align="left">Value</th><th align="left">Meaning</th></tr> 150 * <tr><td valign="top"><tt>"r"</tt></td> 151 * <td> Open for reading only. Invoking any of the <tt>write</tt> 152 * methods of the resulting object will cause an {@link 153 * java.io.IOException} to be thrown. </td></tr> 154 * <tr><td valign="top"><tt>"rw"</tt></td> 155 * <td> Open for reading and writing. If the file does not already 156 * exist then an attempt will be made to create it. </td></tr> 157 * <tr><td valign="top"><tt>"rws"</tt></td> 158 * <td> Open for reading and writing, as with <tt>"rw"</tt>, and also 159 * require that every update to the file's content or metadata be 160 * written synchronously to the underlying storage device. </td></tr> 161 * <tr><td valign="top"><tt>"rwd" </tt></td> 162 * <td> Open for reading and writing, as with <tt>"rw"</tt>, and also 163 * require that every update to the file's content be written 164 * synchronously to the underlying storage device. </td></tr> 165 * </table> 166 * 167 * The <tt>"rws"</tt> and <tt>"rwd"</tt> modes work much like the {@link 168 * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of 169 * the {@link java.nio.channels.FileChannel} class, passing arguments of 170 * <tt>true</tt> and <tt>false</tt>, respectively, except that they always 171 * apply to every I/O operation and are therefore often more efficient. If 172 * the file resides on a local storage device then when an invocation of a 173 * method of this class returns it is guaranteed that all changes made to 174 * the file by that invocation will have been written to that device. This 175 * is useful for ensuring that critical information is not lost in the 176 * event of a system crash. If the file does not reside on a local device 177 * then no such guarantee is made. 178 * 179 * <p>The <tt>"rwd"</tt> mode can be used to reduce the number of I/O 180 * operations performed. Using <tt>"rwd"</tt> only requires updates to the 181 * file's content to be written to storage; using <tt>"rws"</tt> requires 182 * updates to both the file's content and its metadata to be written, which 183 * generally requires at least one more low-level I/O operation. 184 * 185 * <p>If there is a security manager, its {@code checkRead} method is 186 * called with the pathname of the {@code file} argument as its 187 * argument to see if read access to the file is allowed. If the mode 188 * allows writing, the security manager's {@code checkWrite} method is 189 * also called with the path argument to see if write access to the file is 190 * allowed. 191 * 192 * @param file the file object 193 * @param mode the access mode, as described 194 * <a href="#mode">above</a> 195 * @exception IllegalArgumentException if the mode argument is not equal 196 * to one of <tt>"r"</tt>, <tt>"rw"</tt>, <tt>"rws"</tt>, or 197 * <tt>"rwd"</tt> 198 * @exception FileNotFoundException 199 * if the mode is <tt>"r"</tt> but the given file object does 200 * not denote an existing regular file, or if the mode begins 201 * with <tt>"rw"</tt> but the given file object does not denote 202 * an existing, writable regular file and a new regular file of 203 * that name cannot be created, or if some other error occurs 204 * while opening or creating the file 205 * @exception SecurityException if a security manager exists and its 206 * {@code checkRead} method denies read access to the file 207 * or the mode is "rw" and the security manager's 208 * {@code checkWrite} method denies write access to the file 209 * @see java.lang.SecurityManager#checkRead(java.lang.String) 210 * @see java.lang.SecurityManager#checkWrite(java.lang.String) 211 * @see java.nio.channels.FileChannel#force(boolean) 212 * @revised 1.4 213 * @spec JSR-51 214 */ 215 public RandomAccessFile(File file, String mode) 216 throws FileNotFoundException 217 { 218 String name = (file != null ? file.getPath() : null); 219 this.mode = -1; 220 if (mode.equals("r")) { 221 this.mode = O_RDONLY; 222 } else if (mode.startsWith("rw")) { 223 // Android-changed: Added. O_CREAT 224 this.mode = O_RDWR | O_CREAT; 225 rw = true; 226 if (mode.length() > 2) { 227 if (mode.equals("rws")) { 228 syncMetadata = true; 229 } else if (mode.equals("rwd")) { 230 // Android-changed: Should this be O_DSYNC and the above O_SYNC ? 231 this.mode |= O_SYNC; 232 } else { 233 this.mode = -1; 234 } 235 } 236 } 237 238 if (this.mode < 0) { 239 throw new IllegalArgumentException("Illegal mode \"" + mode 240 + "\" must be one of " 241 + "\"r\", \"rw\", \"rws\"," 242 + " or \"rwd\""); 243 } 244 245 if (name == null) { 246 throw new NullPointerException("file == null"); 247 } 248 249 if (file.isInvalid()) { 250 throw new FileNotFoundException("Invalid file path"); 251 } 252 this.path = name; 253 254 // Android-changed: Use IoBridge.open() instead of open. 255 fd = IoBridge.open(file.getPath(), this.mode); 256 if (syncMetadata) { 257 try { 258 fd.sync(); 259 } catch (IOException e) { 260 // Ignored 261 } 262 } 263 guard.open("close"); 264 } 265 266 /** 267 * Returns the opaque file descriptor object associated with this 268 * stream. 269 * 270 * @return the file descriptor object associated with this stream. 271 * @exception IOException if an I/O error occurs. 272 * @see java.io.FileDescriptor 273 */ 274 public final FileDescriptor getFD() throws IOException { 275 if (fd != null) { 276 return fd; 277 } 278 throw new IOException(); 279 } 280 281 /** 282 * Returns the unique {@link java.nio.channels.FileChannel FileChannel} 283 * object associated with this file. 284 * 285 * <p> The {@link java.nio.channels.FileChannel#position() 286 * position} of the returned channel will always be equal to 287 * this object's file-pointer offset as returned by the {@link 288 * #getFilePointer getFilePointer} method. Changing this object's 289 * file-pointer offset, whether explicitly or by reading or writing bytes, 290 * will change the position of the channel, and vice versa. Changing the 291 * file's length via this object will change the length seen via the file 292 * channel, and vice versa. 293 * 294 * @return the file channel associated with this file 295 * 296 * @since 1.4 297 * @spec JSR-51 298 */ 299 public final FileChannel getChannel() { 300 synchronized (this) { 301 if (channel == null) { 302 channel = FileChannelImpl.open(fd, path, true, rw, this); 303 } 304 return channel; 305 } 306 } 307 308 /** 309 * Reads a byte of data from this file. The byte is returned as an 310 * integer in the range 0 to 255 ({@code 0x00-0x0ff}). This 311 * method blocks if no input is yet available. 312 * <p> 313 * Although {@code RandomAccessFile} is not a subclass of 314 * {@code InputStream}, this method behaves in exactly the same 315 * way as the {@link InputStream#read()} method of 316 * {@code InputStream}. 317 * 318 * @return the next byte of data, or {@code -1} if the end of the 319 * file has been reached. 320 * @exception IOException if an I/O error occurs. Not thrown if 321 * end-of-file has been reached. 322 */ 323 public int read() throws IOException { 324 return (read(scratch, 0, 1) != -1) ? scratch[0] & 0xff : -1; 325 } 326 327 /** 328 * Reads a sub array as a sequence of bytes. 329 * @param b the buffer into which the data is read. 330 * @param off the start offset of the data. 331 * @param len the number of bytes to read. 332 * @exception IOException If an I/O error has occurred. 333 */ 334 private int readBytes(byte b[], int off, int len) throws IOException { 335 ioTracker.trackIo(len, IoTracker.Mode.READ); 336 return IoBridge.read(fd, b, off, len); 337 } 338 339 /** 340 * Reads up to {@code len} bytes of data from this file into an 341 * array of bytes. This method blocks until at least one byte of input 342 * is available. 343 * <p> 344 * Although {@code RandomAccessFile} is not a subclass of 345 * {@code InputStream}, this method behaves in exactly the 346 * same way as the {@link InputStream#read(byte[], int, int)} method of 347 * {@code InputStream}. 348 * 349 * @param b the buffer into which the data is read. 350 * @param off the start offset in array {@code b} 351 * at which the data is written. 352 * @param len the maximum number of bytes read. 353 * @return the total number of bytes read into the buffer, or 354 * {@code -1} if there is no more data because the end of 355 * the file has been reached. 356 * @exception IOException If the first byte cannot be read for any reason 357 * other than end of file, or if the random access file has been closed, or if 358 * some other I/O error occurs. 359 * @exception NullPointerException If {@code b} is {@code null}. 360 * @exception IndexOutOfBoundsException If {@code off} is negative, 361 * {@code len} is negative, or {@code len} is greater than 362 * {@code b.length - off} 363 */ 364 public int read(byte b[], int off, int len) throws IOException { 365 return readBytes(b, off, len); 366 } 367 368 /** 369 * Reads up to {@code b.length} bytes of data from this file 370 * into an array of bytes. This method blocks until at least one byte 371 * of input is available. 372 * <p> 373 * Although {@code RandomAccessFile} is not a subclass of 374 * {@code InputStream}, this method behaves in exactly the 375 * same way as the {@link InputStream#read(byte[])} method of 376 * {@code InputStream}. 377 * 378 * @param b the buffer into which the data is read. 379 * @return the total number of bytes read into the buffer, or 380 * {@code -1} if there is no more data because the end of 381 * this file has been reached. 382 * @exception IOException If the first byte cannot be read for any reason 383 * other than end of file, or if the random access file has been closed, or if 384 * some other I/O error occurs. 385 * @exception NullPointerException If {@code b} is {@code null}. 386 */ 387 public int read(byte b[]) throws IOException { 388 return readBytes(b, 0, b.length); 389 } 390 391 /** 392 * Reads {@code b.length} bytes from this file into the byte 393 * array, starting at the current file pointer. This method reads 394 * repeatedly from the file until the requested number of bytes are 395 * read. This method blocks until the requested number of bytes are 396 * read, the end of the stream is detected, or an exception is thrown. 397 * 398 * @param b the buffer into which the data is read. 399 * @exception EOFException if this file reaches the end before reading 400 * all the bytes. 401 * @exception IOException if an I/O error occurs. 402 */ 403 public final void readFully(byte b[]) throws IOException { 404 readFully(b, 0, b.length); 405 } 406 407 /** 408 * Reads exactly {@code len} bytes from this file into the byte 409 * array, starting at the current file pointer. This method reads 410 * repeatedly from the file until the requested number of bytes are 411 * read. This method blocks until the requested number of bytes are 412 * read, the end of the stream is detected, or an exception is thrown. 413 * 414 * @param b the buffer into which the data is read. 415 * @param off the start offset of the data. 416 * @param len the number of bytes to read. 417 * @exception EOFException if this file reaches the end before reading 418 * all the bytes. 419 * @exception IOException if an I/O error occurs. 420 */ 421 public final void readFully(byte b[], int off, int len) throws IOException { 422 int n = 0; 423 do { 424 int count = this.read(b, off + n, len - n); 425 if (count < 0) 426 throw new EOFException(); 427 n += count; 428 } while (n < len); 429 } 430 431 /** 432 * Attempts to skip over {@code n} bytes of input discarding the 433 * skipped bytes. 434 * <p> 435 * 436 * This method may skip over some smaller number of bytes, possibly zero. 437 * This may result from any of a number of conditions; reaching end of 438 * file before {@code n} bytes have been skipped is only one 439 * possibility. This method never throws an {@code EOFException}. 440 * The actual number of bytes skipped is returned. If {@code n} 441 * is negative, no bytes are skipped. 442 * 443 * @param n the number of bytes to be skipped. 444 * @return the actual number of bytes skipped. 445 * @exception IOException if an I/O error occurs. 446 */ 447 public int skipBytes(int n) throws IOException { 448 long pos; 449 long len; 450 long newpos; 451 452 if (n <= 0) { 453 return 0; 454 } 455 pos = getFilePointer(); 456 len = length(); 457 newpos = pos + n; 458 if (newpos > len) { 459 newpos = len; 460 } 461 seek(newpos); 462 463 /* return the actual number of bytes skipped */ 464 return (int) (newpos - pos); 465 } 466 467 // 'Write' primitives 468 469 /** 470 * Writes the specified byte to this file. The write starts at 471 * the current file pointer. 472 * 473 * @param b the {@code byte} to be written. 474 * @exception IOException if an I/O error occurs. 475 */ 476 public void write(int b) throws IOException { 477 scratch[0] = (byte) (b & 0xff); 478 write(scratch, 0, 1); 479 } 480 481 /** 482 * Writes a sub array as a sequence of bytes. 483 * @param b the data to be written 484 * @param off the start offset in the data 485 * @param len the number of bytes that are written 486 * @exception IOException If an I/O error has occurred. 487 */ 488 private void writeBytes(byte b[], int off, int len) throws IOException { 489 ioTracker.trackIo(len, IoTracker.Mode.WRITE); 490 IoBridge.write(fd, b, off, len); 491 // if we are in "rws" mode, attempt to sync file+metadata 492 if (syncMetadata) { 493 fd.sync(); 494 } 495 } 496 497 /** 498 * Writes {@code b.length} bytes from the specified byte array 499 * to this file, starting at the current file pointer. 500 * 501 * @param b the data. 502 * @exception IOException if an I/O error occurs. 503 */ 504 public void write(byte b[]) throws IOException { 505 writeBytes(b, 0, b.length); 506 } 507 508 /** 509 * Writes {@code len} bytes from the specified byte array 510 * starting at offset {@code off} to this file. 511 * 512 * @param b the data. 513 * @param off the start offset in the data. 514 * @param len the number of bytes to write. 515 * @exception IOException if an I/O error occurs. 516 */ 517 public void write(byte b[], int off, int len) throws IOException { 518 writeBytes(b, off, len); 519 } 520 521 // 'Random access' stuff 522 523 /** 524 * Returns the current offset in this file. 525 * 526 * @return the offset from the beginning of the file, in bytes, 527 * at which the next read or write occurs. 528 * @exception IOException if an I/O error occurs. 529 */ 530 public long getFilePointer() throws IOException { 531 try { 532 return Libcore.os.lseek(fd, 0L, SEEK_CUR); 533 } catch (ErrnoException errnoException) { 534 throw errnoException.rethrowAsIOException(); 535 } 536 } 537 538 /** 539 * Sets the file-pointer offset, measured from the beginning of this 540 * file, at which the next read or write occurs. The offset may be 541 * set beyond the end of the file. Setting the offset beyond the end 542 * of the file does not change the file length. The file length will 543 * change only by writing after the offset has been set beyond the end 544 * of the file. 545 * 546 * @param offset the offset position, measured in bytes from the 547 * beginning of the file, at which to set the file 548 * pointer. 549 * @exception IOException if {@code pos} is less than 550 * {@code 0} or if an I/O error occurs. 551 */ 552 public void seek(long offset) throws IOException { 553 if (offset < 0) { 554 throw new IOException("offset < 0: " + offset); 555 } 556 try { 557 Libcore.os.lseek(fd, offset, SEEK_SET); 558 ioTracker.reset(); 559 } catch (ErrnoException errnoException) { 560 throw errnoException.rethrowAsIOException(); 561 } 562 } 563 564 /** 565 * Returns the length of this file. 566 * 567 * @return the length of this file, measured in bytes. 568 * @exception IOException if an I/O error occurs. 569 */ 570 public long length() throws IOException { 571 try { 572 return Libcore.os.fstat(fd).st_size; 573 } catch (ErrnoException errnoException) { 574 throw errnoException.rethrowAsIOException(); 575 } 576 } 577 578 /** 579 * Sets the length of this file. 580 * 581 * <p> If the present length of the file as returned by the 582 * {@code length} method is greater than the {@code newLength} 583 * argument then the file will be truncated. In this case, if the file 584 * offset as returned by the {@code getFilePointer} method is greater 585 * than {@code newLength} then after this method returns the offset 586 * will be equal to {@code newLength}. 587 * 588 * <p> If the present length of the file as returned by the 589 * {@code length} method is smaller than the {@code newLength} 590 * argument then the file will be extended. In this case, the contents of 591 * the extended portion of the file are not defined. 592 * 593 * @param newLength The desired length of the file 594 * @exception IOException If an I/O error occurs 595 * @since 1.2 596 */ 597 public void setLength(long newLength) throws IOException { 598 if (newLength < 0) { 599 throw new IllegalArgumentException("newLength < 0"); 600 } 601 try { 602 Libcore.os.ftruncate(fd, newLength); 603 } catch (ErrnoException errnoException) { 604 throw errnoException.rethrowAsIOException(); 605 } 606 607 long filePointer = getFilePointer(); 608 if (filePointer > newLength) { 609 seek(newLength); 610 } 611 // if we are in "rws" mode, attempt to sync file+metadata 612 if (syncMetadata) { 613 fd.sync(); 614 } 615 } 616 617 618 /** 619 * Closes this random access file stream and releases any system 620 * resources associated with the stream. A closed random access 621 * file cannot perform input or output operations and cannot be 622 * reopened. 623 * 624 * <p> If this file has an associated channel then the channel is closed 625 * as well. 626 * 627 * @exception IOException if an I/O error occurs. 628 * 629 * @revised 1.4 630 * @spec JSR-51 631 */ 632 public void close() throws IOException { 633 guard.close(); 634 synchronized (closeLock) { 635 if (closed) { 636 return; 637 } 638 closed = true; 639 } 640 641 if (channel != null && channel.isOpen()) { 642 channel.close(); 643 } 644 IoBridge.closeAndSignalBlockedThreads(fd); 645 } 646 647 // 648 // Some "reading/writing Java data types" methods stolen from 649 // DataInputStream and DataOutputStream. 650 // 651 652 /** 653 * Reads a {@code boolean} from this file. This method reads a 654 * single byte from the file, starting at the current file pointer. 655 * A value of {@code 0} represents 656 * {@code false}. Any other value represents {@code true}. 657 * This method blocks until the byte is read, the end of the stream 658 * is detected, or an exception is thrown. 659 * 660 * @return the {@code boolean} value read. 661 * @exception EOFException if this file has reached the end. 662 * @exception IOException if an I/O error occurs. 663 */ 664 public final boolean readBoolean() throws IOException { 665 int ch = this.read(); 666 if (ch < 0) 667 throw new EOFException(); 668 return (ch != 0); 669 } 670 671 /** 672 * Reads a signed eight-bit value from this file. This method reads a 673 * byte from the file, starting from the current file pointer. 674 * If the byte read is {@code b}, where 675 * <code>0 <= b <= 255</code>, 676 * then the result is: 677 * <blockquote><pre> 678 * (byte)(b) 679 * </pre></blockquote> 680 * <p> 681 * This method blocks until the byte is read, the end of the stream 682 * is detected, or an exception is thrown. 683 * 684 * @return the next byte of this file as a signed eight-bit 685 * {@code byte}. 686 * @exception EOFException if this file has reached the end. 687 * @exception IOException if an I/O error occurs. 688 */ 689 public final byte readByte() throws IOException { 690 int ch = this.read(); 691 if (ch < 0) 692 throw new EOFException(); 693 return (byte)(ch); 694 } 695 696 /** 697 * Reads an unsigned eight-bit number from this file. This method reads 698 * a byte from this file, starting at the current file pointer, 699 * and returns that byte. 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, interpreted as an unsigned 705 * eight-bit number. 706 * @exception EOFException if this file has reached the end. 707 * @exception IOException if an I/O error occurs. 708 */ 709 public final int readUnsignedByte() throws IOException { 710 int ch = this.read(); 711 if (ch < 0) 712 throw new EOFException(); 713 return ch; 714 } 715 716 /** 717 * Reads a signed 16-bit number from this file. The method reads two 718 * bytes from this file, starting at the current file pointer. 719 * If the two bytes read, in order, are 720 * {@code b1} and {@code b2}, where each of the two values is 721 * between {@code 0} and {@code 255}, inclusive, then the 722 * result is equal to: 723 * <blockquote><pre> 724 * (short)((b1 << 8) | b2) 725 * </pre></blockquote> 726 * <p> 727 * This method blocks until the two bytes are read, the end of the 728 * stream is detected, or an exception is thrown. 729 * 730 * @return the next two bytes of this file, interpreted as a signed 731 * 16-bit number. 732 * @exception EOFException if this file reaches the end before reading 733 * two bytes. 734 * @exception IOException if an I/O error occurs. 735 */ 736 public final short readShort() throws IOException { 737 int ch1 = this.read(); 738 int ch2 = this.read(); 739 if ((ch1 | ch2) < 0) 740 throw new EOFException(); 741 return (short)((ch1 << 8) + (ch2 << 0)); 742 } 743 744 /** 745 * Reads an unsigned 16-bit number from this file. This method reads 746 * two bytes from the file, starting at the current file pointer. 747 * If the bytes read, in order, are 748 * {@code b1} and {@code b2}, where 749 * <code>0 <= b1, b2 <= 255</code>, 750 * then the result is equal to: 751 * <blockquote><pre> 752 * (b1 << 8) | b2 753 * </pre></blockquote> 754 * <p> 755 * This method blocks until the two bytes are read, the end of the 756 * stream is detected, or an exception is thrown. 757 * 758 * @return the next two bytes of this file, interpreted as an unsigned 759 * 16-bit integer. 760 * @exception EOFException if this file reaches the end before reading 761 * two bytes. 762 * @exception IOException if an I/O error occurs. 763 */ 764 public final int readUnsignedShort() throws IOException { 765 int ch1 = this.read(); 766 int ch2 = this.read(); 767 if ((ch1 | ch2) < 0) 768 throw new EOFException(); 769 return (ch1 << 8) + (ch2 << 0); 770 } 771 772 /** 773 * Reads a character from this file. This method reads two 774 * bytes from the file, starting at the current file pointer. 775 * If the bytes read, in order, are 776 * {@code b1} and {@code b2}, where 777 * <code>0 <= b1, b2 <= 255</code>, 778 * then the result is equal to: 779 * <blockquote><pre> 780 * (char)((b1 << 8) | b2) 781 * </pre></blockquote> 782 * <p> 783 * This method blocks until the two bytes are read, the end of the 784 * stream is detected, or an exception is thrown. 785 * 786 * @return the next two bytes of this file, interpreted as a 787 * {@code char}. 788 * @exception EOFException if this file reaches the end before reading 789 * two bytes. 790 * @exception IOException if an I/O error occurs. 791 */ 792 public final char readChar() throws IOException { 793 int ch1 = this.read(); 794 int ch2 = this.read(); 795 if ((ch1 | ch2) < 0) 796 throw new EOFException(); 797 return (char)((ch1 << 8) + (ch2 << 0)); 798 } 799 800 /** 801 * Reads a signed 32-bit integer from this file. This method reads 4 802 * bytes from the file, starting at the current file pointer. 803 * If the bytes read, in order, are {@code b1}, 804 * {@code b2}, {@code b3}, and {@code b4}, where 805 * <code>0 <= b1, b2, b3, b4 <= 255</code>, 806 * then the result is equal to: 807 * <blockquote><pre> 808 * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4 809 * </pre></blockquote> 810 * <p> 811 * This method blocks until the four bytes are read, the end of the 812 * stream is detected, or an exception is thrown. 813 * 814 * @return the next four bytes of this file, interpreted as an 815 * {@code int}. 816 * @exception EOFException if this file reaches the end before reading 817 * four bytes. 818 * @exception IOException if an I/O error occurs. 819 */ 820 public final int readInt() throws IOException { 821 int ch1 = this.read(); 822 int ch2 = this.read(); 823 int ch3 = this.read(); 824 int ch4 = this.read(); 825 if ((ch1 | ch2 | ch3 | ch4) < 0) 826 throw new EOFException(); 827 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); 828 } 829 830 /** 831 * Reads a signed 64-bit integer from this file. This method reads eight 832 * bytes from the file, starting at the current file pointer. 833 * If the bytes read, in order, are 834 * {@code b1}, {@code b2}, {@code b3}, 835 * {@code b4}, {@code b5}, {@code b6}, 836 * {@code b7}, and {@code b8,} where: 837 * <blockquote><pre> 838 * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255, 839 * </pre></blockquote> 840 * <p> 841 * then the result is equal to: 842 * <blockquote><pre> 843 * ((long)b1 << 56) + ((long)b2 << 48) 844 * + ((long)b3 << 40) + ((long)b4 << 32) 845 * + ((long)b5 << 24) + ((long)b6 << 16) 846 * + ((long)b7 << 8) + b8 847 * </pre></blockquote> 848 * <p> 849 * This method blocks until the eight bytes are read, the end of the 850 * stream is detected, or an exception is thrown. 851 * 852 * @return the next eight bytes of this file, interpreted as a 853 * {@code long}. 854 * @exception EOFException if this file reaches the end before reading 855 * eight bytes. 856 * @exception IOException if an I/O error occurs. 857 */ 858 public final long readLong() throws IOException { 859 return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL); 860 } 861 862 /** 863 * Reads a {@code float} from this file. This method reads an 864 * {@code int} value, starting at the current file pointer, 865 * as if by the {@code readInt} method 866 * and then converts that {@code int} to a {@code float} 867 * using the {@code intBitsToFloat} method in class 868 * {@code Float}. 869 * <p> 870 * This method blocks until the four bytes are read, the end of the 871 * stream is detected, or an exception is thrown. 872 * 873 * @return the next four bytes of this file, interpreted as a 874 * {@code float}. 875 * @exception EOFException if this file reaches the end before reading 876 * four bytes. 877 * @exception IOException if an I/O error occurs. 878 * @see java.io.RandomAccessFile#readInt() 879 * @see java.lang.Float#intBitsToFloat(int) 880 */ 881 public final float readFloat() throws IOException { 882 return Float.intBitsToFloat(readInt()); 883 } 884 885 /** 886 * Reads a {@code double} from this file. This method reads a 887 * {@code long} value, starting at the current file pointer, 888 * as if by the {@code readLong} method 889 * and then converts that {@code long} to a {@code double} 890 * using the {@code longBitsToDouble} method in 891 * class {@code Double}. 892 * <p> 893 * This method blocks until the eight bytes are read, the end of the 894 * stream is detected, or an exception is thrown. 895 * 896 * @return the next eight bytes of this file, interpreted as a 897 * {@code double}. 898 * @exception EOFException if this file reaches the end before reading 899 * eight bytes. 900 * @exception IOException if an I/O error occurs. 901 * @see java.io.RandomAccessFile#readLong() 902 * @see java.lang.Double#longBitsToDouble(long) 903 */ 904 public final double readDouble() throws IOException { 905 return Double.longBitsToDouble(readLong()); 906 } 907 908 /** 909 * Reads the next line of text from this file. This method successively 910 * reads bytes from the file, starting at the current file pointer, 911 * until it reaches a line terminator or the end 912 * of the file. Each byte is converted into a character by taking the 913 * byte's value for the lower eight bits of the character and setting the 914 * high eight bits of the character to zero. This method does not, 915 * therefore, support the full Unicode character set. 916 * 917 * <p> A line of text is terminated by a carriage-return character 918 * ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a 919 * carriage-return character immediately followed by a newline character, 920 * or the end of the file. Line-terminating characters are discarded and 921 * are not included as part of the string returned. 922 * 923 * <p> This method blocks until a newline character is read, a carriage 924 * return and the byte following it are read (to see if it is a newline), 925 * the end of the file is reached, or an exception is thrown. 926 * 927 * @return the next line of text from this file, or null if end 928 * of file is encountered before even one byte is read. 929 * @exception IOException if an I/O error occurs. 930 */ 931 932 public final String readLine() throws IOException { 933 StringBuffer input = new StringBuffer(); 934 int c = -1; 935 boolean eol = false; 936 937 while (!eol) { 938 switch (c = read()) { 939 case -1: 940 case '\n': 941 eol = true; 942 break; 943 case '\r': 944 eol = true; 945 long cur = getFilePointer(); 946 if ((read()) != '\n') { 947 seek(cur); 948 } 949 break; 950 default: 951 input.append((char)c); 952 break; 953 } 954 } 955 956 if ((c == -1) && (input.length() == 0)) { 957 return null; 958 } 959 return input.toString(); 960 } 961 962 /** 963 * Reads in a string from this file. The string has been encoded 964 * using a 965 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 966 * format. 967 * <p> 968 * The first two bytes are read, starting from the current file 969 * pointer, as if by 970 * {@code readUnsignedShort}. This value gives the number of 971 * following bytes that are in the encoded string, not 972 * the length of the resulting string. The following bytes are then 973 * interpreted as bytes encoding characters in the modified UTF-8 format 974 * and are converted into characters. 975 * <p> 976 * This method blocks until all the bytes are read, the end of the 977 * stream is detected, or an exception is thrown. 978 * 979 * @return a Unicode string. 980 * @exception EOFException if this file reaches the end before 981 * reading all the bytes. 982 * @exception IOException if an I/O error occurs. 983 * @exception UTFDataFormatException if the bytes do not represent 984 * valid modified UTF-8 encoding of a Unicode string. 985 * @see java.io.RandomAccessFile#readUnsignedShort() 986 */ 987 public final String readUTF() throws IOException { 988 return DataInputStream.readUTF(this); 989 } 990 991 /** 992 * Writes a {@code boolean} to the file as a one-byte value. The 993 * value {@code true} is written out as the value 994 * {@code (byte)1}; the value {@code false} is written out 995 * as the value {@code (byte)0}. The write starts at 996 * the current position of the file pointer. 997 * 998 * @param v a {@code boolean} value to be written. 999 * @exception IOException if an I/O error occurs. 1000 */ 1001 public final void writeBoolean(boolean v) throws IOException { 1002 write(v ? 1 : 0); 1003 //written++; 1004 } 1005 1006 /** 1007 * Writes a {@code byte} to the file as a one-byte value. The 1008 * write starts at the current position of the file pointer. 1009 * 1010 * @param v a {@code byte} value to be written. 1011 * @exception IOException if an I/O error occurs. 1012 */ 1013 public final void writeByte(int v) throws IOException { 1014 write(v); 1015 //written++; 1016 } 1017 1018 /** 1019 * Writes a {@code short} to the file as two bytes, high byte first. 1020 * The write starts at the current position of the file pointer. 1021 * 1022 * @param v a {@code short} to be written. 1023 * @exception IOException if an I/O error occurs. 1024 */ 1025 public final void writeShort(int v) throws IOException { 1026 write((v >>> 8) & 0xFF); 1027 write((v >>> 0) & 0xFF); 1028 //written += 2; 1029 } 1030 1031 /** 1032 * Writes a {@code char} to the file as a two-byte value, high 1033 * byte first. The write starts at the current position of the 1034 * file pointer. 1035 * 1036 * @param v a {@code char} value to be written. 1037 * @exception IOException if an I/O error occurs. 1038 */ 1039 public final void writeChar(int v) throws IOException { 1040 write((v >>> 8) & 0xFF); 1041 write((v >>> 0) & 0xFF); 1042 //written += 2; 1043 } 1044 1045 /** 1046 * Writes an {@code int} to the file as four bytes, high byte first. 1047 * The write starts at the current position of the file pointer. 1048 * 1049 * @param v an {@code int} to be written. 1050 * @exception IOException if an I/O error occurs. 1051 */ 1052 public final void writeInt(int v) throws IOException { 1053 write((v >>> 24) & 0xFF); 1054 write((v >>> 16) & 0xFF); 1055 write((v >>> 8) & 0xFF); 1056 write((v >>> 0) & 0xFF); 1057 //written += 4; 1058 } 1059 1060 /** 1061 * Writes a {@code long} to the file as eight bytes, high byte first. 1062 * The write starts at the current position of the file pointer. 1063 * 1064 * @param v a {@code long} to be written. 1065 * @exception IOException if an I/O error occurs. 1066 */ 1067 public final void writeLong(long v) throws IOException { 1068 write((int)(v >>> 56) & 0xFF); 1069 write((int)(v >>> 48) & 0xFF); 1070 write((int)(v >>> 40) & 0xFF); 1071 write((int)(v >>> 32) & 0xFF); 1072 write((int)(v >>> 24) & 0xFF); 1073 write((int)(v >>> 16) & 0xFF); 1074 write((int)(v >>> 8) & 0xFF); 1075 write((int)(v >>> 0) & 0xFF); 1076 //written += 8; 1077 } 1078 1079 /** 1080 * Converts the float argument to an {@code int} using the 1081 * {@code floatToIntBits} method in class {@code Float}, 1082 * and then writes that {@code int} value to the file as a 1083 * four-byte quantity, high byte first. The write starts at the 1084 * current position of the file pointer. 1085 * 1086 * @param v a {@code float} value to be written. 1087 * @exception IOException if an I/O error occurs. 1088 * @see java.lang.Float#floatToIntBits(float) 1089 */ 1090 public final void writeFloat(float v) throws IOException { 1091 writeInt(Float.floatToIntBits(v)); 1092 } 1093 1094 /** 1095 * Converts the double argument to a {@code long} using the 1096 * {@code doubleToLongBits} method in class {@code Double}, 1097 * and then writes that {@code long} value to the file as an 1098 * eight-byte quantity, high byte first. The write starts at the current 1099 * position of the file pointer. 1100 * 1101 * @param v a {@code double} value to be written. 1102 * @exception IOException if an I/O error occurs. 1103 * @see java.lang.Double#doubleToLongBits(double) 1104 */ 1105 public final void writeDouble(double v) throws IOException { 1106 writeLong(Double.doubleToLongBits(v)); 1107 } 1108 1109 /** 1110 * Writes the string to the file as a sequence of bytes. Each 1111 * character in the string is written out, in sequence, by discarding 1112 * its high eight bits. The write starts at the current position of 1113 * the file pointer. 1114 * 1115 * @param s a string of bytes to be written. 1116 * @exception IOException if an I/O error occurs. 1117 */ 1118 @SuppressWarnings("deprecation") 1119 public final void writeBytes(String s) throws IOException { 1120 int len = s.length(); 1121 byte[] b = new byte[len]; 1122 s.getBytes(0, len, b, 0); 1123 writeBytes(b, 0, len); 1124 } 1125 1126 /** 1127 * Writes a string to the file as a sequence of characters. Each 1128 * character is written to the data output stream as if by the 1129 * {@code writeChar} method. The write starts at the current 1130 * position of the file pointer. 1131 * 1132 * @param s a {@code String} value to be written. 1133 * @exception IOException if an I/O error occurs. 1134 * @see java.io.RandomAccessFile#writeChar(int) 1135 */ 1136 public final void writeChars(String s) throws IOException { 1137 int clen = s.length(); 1138 int blen = 2*clen; 1139 byte[] b = new byte[blen]; 1140 char[] c = new char[clen]; 1141 s.getChars(0, clen, c, 0); 1142 for (int i = 0, j = 0; i < clen; i++) { 1143 b[j++] = (byte)(c[i] >>> 8); 1144 b[j++] = (byte)(c[i] >>> 0); 1145 } 1146 writeBytes(b, 0, blen); 1147 } 1148 1149 /** 1150 * Writes a string to the file using 1151 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> 1152 * encoding in a machine-independent manner. 1153 * <p> 1154 * First, two bytes are written to the file, starting at the 1155 * current file pointer, as if by the 1156 * {@code writeShort} method giving the number of bytes to 1157 * follow. This value is the number of bytes actually written out, 1158 * not the length of the string. Following the length, each character 1159 * of the string is output, in sequence, using the modified UTF-8 encoding 1160 * for each character. 1161 * 1162 * @param str a string to be written. 1163 * @exception IOException if an I/O error occurs. 1164 */ 1165 public final void writeUTF(String str) throws IOException { 1166 DataOutputStream.writeUTF(str, this); 1167 } 1168 1169 @Override protected void finalize() throws Throwable { 1170 try { 1171 if (guard != null) { 1172 guard.warnIfOpen(); 1173 } 1174 close(); 1175 } finally { 1176 super.finalize(); 1177 } 1178 } 1179 } 1180
