001 /* ByteBuffer.java -- 002 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package java.nio; 040 041 /** 042 * @since 1.4 043 */ 044 public abstract class ByteBuffer extends Buffer 045 implements Comparable<ByteBuffer> 046 { 047 ByteOrder endian = ByteOrder.BIG_ENDIAN; 048 049 int array_offset; 050 byte[] backing_buffer; 051 052 ByteBuffer (int capacity, int limit, int position, int mark) 053 { 054 super (capacity, limit, position, mark); 055 } 056 057 /** 058 * Allocates a new direct byte buffer. 059 */ 060 public static ByteBuffer allocateDirect (int capacity) 061 { 062 return DirectByteBufferImpl.allocate (capacity); 063 } 064 065 /** 066 * Allocates a new <code>ByteBuffer</code> object with a given capacity. 067 */ 068 public static ByteBuffer allocate (int capacity) 069 { 070 return wrap(new byte[capacity], 0, capacity); 071 } 072 073 /** 074 * Wraps a <code>byte</code> array into a <code>ByteBuffer</code> 075 * object. 076 * 077 * @exception IndexOutOfBoundsException If the preconditions on the offset 078 * and length parameters do not hold 079 */ 080 public static final ByteBuffer wrap (byte[] array, int offset, int length) 081 { 082 // FIXME: In GCJ and other implementations where arrays may not 083 // move we might consider, at least when offset==0: 084 // return new DirectByteBufferImpl(array, 085 // address_of_data(array) + offset, 086 // length, length, 0, false); 087 // This may be more efficient, mainly because we can then use the 088 // same logic for all ByteBuffers. 089 090 return new ByteBufferImpl (array, 0, array.length, offset + length, offset, -1, false); 091 } 092 093 /** 094 * Wraps a <code>byte</code> array into a <code>ByteBuffer</code> 095 * object. 096 */ 097 public static final ByteBuffer wrap (byte[] array) 098 { 099 return wrap (array, 0, array.length); 100 } 101 102 /** 103 * This method transfers <code>byte</code>s from this buffer into the given 104 * destination array. Before the transfer, it checks if there are fewer than 105 * length <code>byte</code>s remaining in this buffer. 106 * 107 * @param dst The destination array 108 * @param offset The offset within the array of the first <code>byte</code> 109 * to be written; must be non-negative and no larger than dst.length. 110 * @param length The maximum number of bytes to be written to the given array; 111 * must be non-negative and no larger than dst.length - offset. 112 * 113 * @exception BufferUnderflowException If there are fewer than length 114 * <code>byte</code>s remaining in this buffer. 115 * @exception IndexOutOfBoundsException If the preconditions on the offset 116 * and length parameters do not hold. 117 */ 118 public ByteBuffer get (byte[] dst, int offset, int length) 119 { 120 checkArraySize(dst.length, offset, length); 121 checkForUnderflow(length); 122 123 for (int i = offset; i < offset + length; i++) 124 { 125 dst [i] = get (); 126 } 127 128 return this; 129 } 130 131 /** 132 * This method transfers <code>byte</code>s from this buffer into the given 133 * destination array. 134 * 135 * @param dst The byte array to write into. 136 * 137 * @exception BufferUnderflowException If there are fewer than dst.length 138 * <code>byte</code>s remaining in this buffer. 139 */ 140 public ByteBuffer get (byte[] dst) 141 { 142 return get (dst, 0, dst.length); 143 } 144 145 /** 146 * Writes the content of the the <code>ByteBUFFER</code> src 147 * into the buffer. Before the transfer, it checks if there is fewer than 148 * <code>src.remaining()</code> space remaining in this buffer. 149 * 150 * @param src The source data. 151 * 152 * @exception BufferOverflowException If there is insufficient space in this 153 * buffer for the remaining <code>byte</code>s in the source buffer. 154 * @exception IllegalArgumentException If the source buffer is this buffer. 155 * @exception ReadOnlyBufferException If this buffer is read-only. 156 */ 157 public ByteBuffer put (ByteBuffer src) 158 { 159 if (src == this) 160 throw new IllegalArgumentException (); 161 162 checkForOverflow(src.remaining()); 163 164 if (src.remaining () > 0) 165 { 166 byte[] toPut = new byte [src.remaining ()]; 167 src.get (toPut); 168 put (toPut); 169 } 170 171 return this; 172 } 173 174 /** 175 * Writes the content of the the <code>byte array</code> src 176 * into the buffer. Before the transfer, it checks if there is fewer than 177 * length space remaining in this buffer. 178 * 179 * @param src The array to copy into the buffer. 180 * @param offset The offset within the array of the first byte to be read; 181 * must be non-negative and no larger than src.length. 182 * @param length The number of bytes to be read from the given array; 183 * must be non-negative and no larger than src.length - offset. 184 * 185 * @exception BufferOverflowException If there is insufficient space in this 186 * buffer for the remaining <code>byte</code>s in the source array. 187 * @exception IndexOutOfBoundsException If the preconditions on the offset 188 * and length parameters do not hold 189 * @exception ReadOnlyBufferException If this buffer is read-only. 190 */ 191 public ByteBuffer put (byte[] src, int offset, int length) 192 { 193 checkArraySize(src.length, offset, length); 194 checkForOverflow(length); 195 196 for (int i = offset; i < offset + length; i++) 197 put (src [i]); 198 199 return this; 200 } 201 202 /** 203 * Writes the content of the the <code>byte array</code> src 204 * into the buffer. 205 * 206 * @param src The array to copy into the buffer. 207 * 208 * @exception BufferOverflowException If there is insufficient space in this 209 * buffer for the remaining <code>byte</code>s in the source array. 210 * @exception ReadOnlyBufferException If this buffer is read-only. 211 */ 212 public final ByteBuffer put (byte[] src) 213 { 214 return put (src, 0, src.length); 215 } 216 217 /** 218 * Tells whether ot not this buffer is backed by an accessible 219 * <code>byte</code> array. 220 */ 221 public final boolean hasArray () 222 { 223 return (backing_buffer != null 224 && !isReadOnly ()); 225 } 226 227 /** 228 * Returns the <code>byte</code> array that backs this buffer. 229 * 230 * @exception ReadOnlyBufferException If this buffer is read-only. 231 * @exception UnsupportedOperationException If this buffer is not backed 232 * by an accessible array. 233 */ 234 public final byte[] array () 235 { 236 if (backing_buffer == null) 237 throw new UnsupportedOperationException (); 238 239 checkIfReadOnly(); 240 241 return backing_buffer; 242 } 243 244 /** 245 * Returns the offset within this buffer's backing array of the first element. 246 * 247 * @exception ReadOnlyBufferException If this buffer is read-only. 248 * @exception UnsupportedOperationException If this buffer is not backed 249 * by an accessible array. 250 */ 251 public final int arrayOffset () 252 { 253 if (backing_buffer == null) 254 throw new UnsupportedOperationException (); 255 256 checkIfReadOnly(); 257 258 return array_offset; 259 } 260 261 /** 262 * Calculates a hash code for this buffer. 263 * 264 * This is done with <code>int</code> arithmetic, 265 * where ** represents exponentiation, by this formula:<br> 266 * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... + 267 * (s[limit()-1]+30)*31**(limit()-1)</code>. 268 * Where s is the buffer data. Note that the hashcode is dependent 269 * on buffer content, and therefore is not useful if the buffer 270 * content may change. 271 * 272 * @return the hash code 273 */ 274 public int hashCode () 275 { 276 int hashCode = get(position()) + 31; 277 int multiplier = 1; 278 for (int i = position() + 1; i < limit(); ++i) 279 { 280 multiplier *= 31; 281 hashCode += (get(i) + 30)*multiplier; 282 } 283 return hashCode; 284 } 285 286 /** 287 * Checks if this buffer is equal to obj. 288 */ 289 public boolean equals (Object obj) 290 { 291 if (obj instanceof ByteBuffer) 292 { 293 return compareTo ((ByteBuffer) obj) == 0; 294 } 295 296 return false; 297 } 298 299 /** 300 * Compares two <code>ByteBuffer</code> objects. 301 * 302 * @exception ClassCastException If obj is not an object derived from 303 * <code>ByteBuffer</code>. 304 */ 305 public int compareTo (ByteBuffer other) 306 { 307 int num = Math.min(remaining(), other.remaining()); 308 int pos_this = position(); 309 int pos_other = other.position(); 310 311 for (int count = 0; count < num; count++) 312 { 313 byte a = get(pos_this++); 314 byte b = other.get(pos_other++); 315 316 if (a == b) 317 continue; 318 319 if (a < b) 320 return -1; 321 322 return 1; 323 } 324 325 return remaining() - other.remaining(); 326 } 327 328 /** 329 * Returns the byte order of this buffer. 330 */ 331 public final ByteOrder order () 332 { 333 return endian; 334 } 335 336 /** 337 * Modifies this buffer's byte order. 338 */ 339 public final ByteBuffer order (ByteOrder endian) 340 { 341 this.endian = endian; 342 return this; 343 } 344 345 /** 346 * Reads the <code>byte</code> at this buffer's current position, 347 * and then increments the position. 348 * 349 * @exception BufferUnderflowException If there are no remaining 350 * <code>byte</code>s in this buffer. 351 */ 352 public abstract byte get (); 353 354 /** 355 * Writes the <code>byte</code> at this buffer's current position, 356 * and then increments the position. 357 * 358 * @exception BufferOverflowException If there no remaining 359 * <code>byte</code>s in this buffer. 360 * @exception ReadOnlyBufferException If this buffer is read-only. 361 */ 362 public abstract ByteBuffer put (byte b); 363 364 /** 365 * Absolute get method. 366 * 367 * @exception IndexOutOfBoundsException If index is negative or not smaller 368 * than the buffer's limit. 369 */ 370 public abstract byte get (int index); 371 372 /** 373 * Absolute put method. 374 * 375 * @exception IndexOutOfBoundsException If index is negative or not smaller 376 * than the buffer's limit. 377 * @exception ReadOnlyBufferException If this buffer is read-only. 378 */ 379 public abstract ByteBuffer put (int index, byte b); 380 381 /** 382 * Compacts this buffer. 383 * 384 * @exception ReadOnlyBufferException If this buffer is read-only. 385 */ 386 public abstract ByteBuffer compact (); 387 388 void shiftDown (int dst_offset, int src_offset, int count) 389 { 390 for (int i = 0; i < count; i++) 391 put(dst_offset + i, get(src_offset + i)); 392 } 393 394 /** 395 * Tells whether or not this buffer is direct. 396 */ 397 public abstract boolean isDirect (); 398 399 /** 400 * Creates a new <code>ByteBuffer</code> whose content is a shared 401 * subsequence of this buffer's content. 402 */ 403 public abstract ByteBuffer slice (); 404 405 /** 406 * Creates a new <code>ByteBuffer</code> that shares this buffer's 407 * content. 408 */ 409 public abstract ByteBuffer duplicate (); 410 411 /** 412 * Creates a new read-only <code>ByteBuffer</code> that shares this 413 * buffer's content. 414 */ 415 public abstract ByteBuffer asReadOnlyBuffer (); 416 417 /** 418 * Creates a view of this byte buffer as a short buffer. 419 */ 420 public abstract ShortBuffer asShortBuffer (); 421 422 /** 423 * Creates a view of this byte buffer as a char buffer. 424 */ 425 public abstract CharBuffer asCharBuffer (); 426 427 /** 428 * Creates a view of this byte buffer as an integer buffer. 429 */ 430 public abstract IntBuffer asIntBuffer (); 431 432 /** 433 * Creates a view of this byte buffer as a long buffer. 434 */ 435 public abstract LongBuffer asLongBuffer (); 436 437 /** 438 * Creates a view of this byte buffer as a float buffer. 439 */ 440 public abstract FloatBuffer asFloatBuffer (); 441 442 /** 443 * Creates a view of this byte buffer as a double buffer. 444 */ 445 public abstract DoubleBuffer asDoubleBuffer (); 446 447 /** 448 * Relative get method for reading a character value. 449 * 450 * @exception BufferUnderflowException If there are fewer than two bytes 451 * remaining in this buffer. 452 */ 453 public abstract char getChar (); 454 455 /** 456 * Relative put method for writing a character value. 457 * 458 * @exception BufferOverflowException If this buffer's current position is 459 * not smaller than its limit. 460 */ 461 public abstract ByteBuffer putChar (char value); 462 463 /** 464 * Absolute get method for reading a character value. 465 * 466 * @exception IndexOutOfBoundsException If there are fewer than two bytes 467 * remaining in this buffer 468 */ 469 public abstract char getChar (int index); 470 471 /** 472 * Absolute put method for writing a character value. 473 * 474 * @exception IndexOutOfBoundsException If index is negative or not smaller 475 * than the buffer's limit, minus one. 476 */ 477 public abstract ByteBuffer putChar (int index, char value); 478 479 /** 480 * Relative get method for reading a short value. 481 * 482 * @exception BufferUnderflowException If index is negative or not smaller 483 * than the buffer's limit, minus one. 484 */ 485 public abstract short getShort (); 486 487 /** 488 * Relative put method for writing a short value. 489 * 490 * @exception BufferOverflowException If this buffer's current position is 491 * not smaller than its limit. 492 */ 493 public abstract ByteBuffer putShort (short value); 494 495 /** 496 * Absolute get method for reading a short value. 497 * 498 * @exception IndexOutOfBoundsException If there are fewer than two bytes 499 * remaining in this buffer 500 */ 501 public abstract short getShort (int index); 502 503 /** 504 * Absolute put method for writing a short value. 505 * 506 * @exception IndexOutOfBoundsException If index is negative or not smaller 507 * than the buffer's limit, minus one. 508 */ 509 public abstract ByteBuffer putShort (int index, short value); 510 511 /** 512 * Relative get method for reading an integer value. 513 * 514 * @exception BufferUnderflowException If there are fewer than four bytes 515 * remaining in this buffer. 516 */ 517 public abstract int getInt (); 518 519 /** 520 * Relative put method for writing an integer value. 521 * 522 * @exception BufferOverflowException If this buffer's current position is 523 * not smaller than its limit. 524 */ 525 public abstract ByteBuffer putInt (int value); 526 527 /** 528 * Absolute get method for reading an integer value. 529 * 530 * @exception IndexOutOfBoundsException If index is negative or not smaller 531 * than the buffer's limit, minus three. 532 */ 533 public abstract int getInt (int index); 534 535 /** 536 * Absolute put method for writing an integer value. 537 * 538 * @exception IndexOutOfBoundsException If index is negative or not smaller 539 * than the buffer's limit, minus three. 540 */ 541 public abstract ByteBuffer putInt (int index, int value); 542 543 /** 544 * Relative get method for reading a long value. 545 * 546 * @exception BufferUnderflowException If there are fewer than eight bytes 547 * remaining in this buffer. 548 */ 549 public abstract long getLong (); 550 551 /** 552 * Relative put method for writing a long value. 553 * 554 * @exception BufferOverflowException If this buffer's current position is 555 * not smaller than its limit. 556 */ 557 public abstract ByteBuffer putLong (long value); 558 559 /** 560 * Absolute get method for reading a long value. 561 * 562 * @exception IndexOutOfBoundsException If index is negative or not smaller 563 * than the buffer's limit, minus seven. 564 */ 565 public abstract long getLong (int index); 566 567 /** 568 * Absolute put method for writing a float value. 569 * 570 * @exception IndexOutOfBoundsException If index is negative or not smaller 571 * than the buffer's limit, minus seven. 572 */ 573 public abstract ByteBuffer putLong (int index, long value); 574 575 /** 576 * Relative get method for reading a float value. 577 * 578 * @exception BufferUnderflowException If there are fewer than four bytes 579 * remaining in this buffer. 580 */ 581 public abstract float getFloat (); 582 583 /** 584 * Relative put method for writing a float value. 585 * 586 * @exception BufferOverflowException If there are fewer than four bytes 587 * remaining in this buffer. 588 */ 589 public abstract ByteBuffer putFloat (float value); 590 591 /** 592 * Absolute get method for reading a float value. 593 * 594 * @exception IndexOutOfBoundsException If index is negative or not smaller 595 * than the buffer's limit, minus three. 596 */ 597 public abstract float getFloat (int index); 598 599 /** 600 * Relative put method for writing a float value. 601 * 602 * @exception IndexOutOfBoundsException If index is negative or not smaller 603 * than the buffer's limit, minus three. 604 */ 605 public abstract ByteBuffer putFloat (int index, float value); 606 607 /** 608 * Relative get method for reading a double value. 609 * 610 * @exception BufferUnderflowException If there are fewer than eight bytes 611 * remaining in this buffer. 612 */ 613 public abstract double getDouble (); 614 615 /** 616 * Relative put method for writing a double value. 617 * 618 * @exception BufferOverflowException If this buffer's current position is 619 * not smaller than its limit. 620 */ 621 public abstract ByteBuffer putDouble (double value); 622 623 /** 624 * Absolute get method for reading a double value. 625 * 626 * @exception IndexOutOfBoundsException If index is negative or not smaller 627 * than the buffer's limit, minus seven. 628 */ 629 public abstract double getDouble (int index); 630 631 /** 632 * Absolute put method for writing a double value. 633 * 634 * @exception IndexOutOfBoundsException If index is negative or not smaller 635 * than the buffer's limit, minus seven. 636 */ 637 public abstract ByteBuffer putDouble (int index, double value); 638 639 /** 640 * Returns a string summarizing the state of this buffer. 641 */ 642 public String toString () 643 { 644 return getClass ().getName () + 645 "[pos=" + position () + 646 " lim=" + limit () + 647 " cap=" + capacity () + "]"; 648 } 649 }