1/* 2 * Copyright (c) 1994, 2006, 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 26package java.io; 27 28/** 29 * A data input stream lets an application read primitive Java data 30 * types from an underlying input stream in a machine-independent 31 * way. An application uses a data output stream to write data that 32 * can later be read by a data input stream. 33 * <p> 34 * DataInputStream is not necessarily safe for multithreaded access. 35 * Thread safety is optional and is the responsibility of users of 36 * methods in this class. 37 * 38 * @author Arthur van Hoff 39 * @see java.io.DataOutputStream 40 * @since JDK1.0 41 */ 42public 43class DataInputStream extends FilterInputStream implements DataInput { 44 45 /** 46 * Creates a DataInputStream that uses the specified 47 * underlying InputStream. 48 * 49 * @param in the specified input stream 50 */ 51 public DataInputStream(InputStream in) { 52 super(in); 53 } 54 55 /** 56 * working arrays initialized on demand by readUTF 57 */ 58 private byte bytearr[] = new byte[80]; 59 private char chararr[] = new char[80]; 60 61 /** 62 * Reads some number of bytes from the contained input stream and 63 * stores them into the buffer array <code>b</code>. The number of 64 * bytes actually read is returned as an integer. This method blocks 65 * until input data is available, end of file is detected, or an 66 * exception is thrown. 67 * 68 * <p>If <code>b</code> is null, a <code>NullPointerException</code> is 69 * thrown. If the length of <code>b</code> is zero, then no bytes are 70 * read and <code>0</code> is returned; otherwise, there is an attempt 71 * to read at least one byte. If no byte is available because the 72 * stream is at end of file, the value <code>-1</code> is returned; 73 * otherwise, at least one byte is read and stored into <code>b</code>. 74 * 75 * <p>The first byte read is stored into element <code>b[0]</code>, the 76 * next one into <code>b[1]</code>, and so on. The number of bytes read 77 * is, at most, equal to the length of <code>b</code>. Let <code>k</code> 78 * be the number of bytes actually read; these bytes will be stored in 79 * elements <code>b[0]</code> through <code>b[k-1]</code>, leaving 80 * elements <code>b[k]</code> through <code>b[b.length-1]</code> 81 * unaffected. 82 * 83 * <p>The <code>read(b)</code> method has the same effect as: 84 * <blockquote><pre> 85 * read(b, 0, b.length) 86 * </pre></blockquote> 87 * 88 * @param b the buffer into which the data is read. 89 * @return the total number of bytes read into the buffer, or 90 * <code>-1</code> if there is no more data because the end 91 * of the stream has been reached. 92 * @exception IOException if the first byte cannot be read for any reason 93 * other than end of file, the stream has been closed and the underlying 94 * input stream does not support reading after close, or another I/O 95 * error occurs. 96 * @see java.io.FilterInputStream#in 97 * @see java.io.InputStream#read(byte[], int, int) 98 */ 99 public final int read(byte b[]) throws IOException { 100 return in.read(b, 0, b.length); 101 } 102 103 /** 104 * Reads up to <code>len</code> bytes of data from the contained 105 * input stream into an array of bytes. An attempt is made to read 106 * as many as <code>len</code> bytes, but a smaller number may be read, 107 * possibly zero. The number of bytes actually read is returned as an 108 * integer. 109 * 110 * <p> This method blocks until input data is available, end of file is 111 * detected, or an exception is thrown. 112 * 113 * <p> If <code>len</code> is zero, then no bytes are read and 114 * <code>0</code> is returned; otherwise, there is an attempt to read at 115 * least one byte. If no byte is available because the stream is at end of 116 * file, the value <code>-1</code> is returned; otherwise, at least one 117 * byte is read and stored into <code>b</code>. 118 * 119 * <p> The first byte read is stored into element <code>b[off]</code>, the 120 * next one into <code>b[off+1]</code>, and so on. The number of bytes read 121 * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of 122 * bytes actually read; these bytes will be stored in elements 123 * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>, 124 * leaving elements <code>b[off+</code><i>k</i><code>]</code> through 125 * <code>b[off+len-1]</code> unaffected. 126 * 127 * <p> In every case, elements <code>b[0]</code> through 128 * <code>b[off]</code> and elements <code>b[off+len]</code> through 129 * <code>b[b.length-1]</code> are unaffected. 130 * 131 * @param b the buffer into which the data is read. 132 * @param off the start offset in the destination array <code>b</code> 133 * @param len the maximum number of bytes read. 134 * @return the total number of bytes read into the buffer, or 135 * <code>-1</code> if there is no more data because the end 136 * of the stream has been reached. 137 * @exception NullPointerException If <code>b</code> is <code>null</code>. 138 * @exception IndexOutOfBoundsException If <code>off</code> is negative, 139 * <code>len</code> is negative, or <code>len</code> is greater than 140 * <code>b.length - off</code> 141 * @exception IOException if the first byte cannot be read for any reason 142 * other than end of file, the stream has been closed and the underlying 143 * input stream does not support reading after close, or another I/O 144 * error occurs. 145 * @see java.io.FilterInputStream#in 146 * @see java.io.InputStream#read(byte[], int, int) 147 */ 148 public final int read(byte b[], int off, int len) throws IOException { 149 return in.read(b, off, len); 150 } 151 152 /** 153 * See the general contract of the <code>readFully</code> 154 * method of <code>DataInput</code>. 155 * <p> 156 * Bytes 157 * for this operation are read from the contained 158 * input stream. 159 * 160 * @param b the buffer into which the data is read. 161 * @exception EOFException if this input stream reaches the end before 162 * reading all the bytes. 163 * @exception IOException the stream has been closed and the contained 164 * input stream does not support reading after close, or 165 * another I/O error occurs. 166 * @see java.io.FilterInputStream#in 167 */ 168 public final void readFully(byte b[]) throws IOException { 169 readFully(b, 0, b.length); 170 } 171 172 /** 173 * See the general contract of the <code>readFully</code> 174 * method of <code>DataInput</code>. 175 * <p> 176 * Bytes 177 * for this operation are read from the contained 178 * input stream. 179 * 180 * @param b the buffer into which the data is read. 181 * @param off the start offset of the data. 182 * @param len the number of bytes to read. 183 * @exception EOFException if this input stream reaches the end before 184 * reading all the bytes. 185 * @exception IOException the stream has been closed and the contained 186 * input stream does not support reading after close, or 187 * another I/O error occurs. 188 * @see java.io.FilterInputStream#in 189 */ 190 public final void readFully(byte b[], int off, int len) throws IOException { 191 if (len < 0) 192 throw new IndexOutOfBoundsException(); 193 int n = 0; 194 while (n < len) { 195 int count = in.read(b, off + n, len - n); 196 if (count < 0) 197 throw new EOFException(); 198 n += count; 199 } 200 } 201 202 /** 203 * See the general contract of the <code>skipBytes</code> 204 * method of <code>DataInput</code>. 205 * <p> 206 * Bytes for this operation are read from the contained 207 * input stream. 208 * 209 * @param n the number of bytes to be skipped. 210 * @return the actual number of bytes skipped. 211 * @exception IOException if the contained input stream does not support 212 * seek, or the stream has been closed and 213 * the contained input stream does not support 214 * reading after close, or another I/O error occurs. 215 */ 216 public final int skipBytes(int n) throws IOException { 217 int total = 0; 218 int cur = 0; 219 220 while ((total<n) && ((cur = (int) in.skip(n-total)) > 0)) { 221 total += cur; 222 } 223 224 return total; 225 } 226 227 /** 228 * See the general contract of the <code>readBoolean</code> 229 * method of <code>DataInput</code>. 230 * <p> 231 * Bytes for this operation are read from the contained 232 * input stream. 233 * 234 * @return the <code>boolean</code> value read. 235 * @exception EOFException if this input stream has reached the end. 236 * @exception IOException the stream has been closed and the contained 237 * input stream does not support reading after close, or 238 * another I/O error occurs. 239 * @see java.io.FilterInputStream#in 240 */ 241 public final boolean readBoolean() throws IOException { 242 int ch = in.read(); 243 if (ch < 0) 244 throw new EOFException(); 245 return (ch != 0); 246 } 247 248 /** 249 * See the general contract of the <code>readByte</code> 250 * method of <code>DataInput</code>. 251 * <p> 252 * Bytes 253 * for this operation are read from the contained 254 * input stream. 255 * 256 * @return the next byte of this input stream as a signed 8-bit 257 * <code>byte</code>. 258 * @exception EOFException if this input stream has reached the end. 259 * @exception IOException the stream has been closed and the contained 260 * input stream does not support reading after close, or 261 * another I/O error occurs. 262 * @see java.io.FilterInputStream#in 263 */ 264 public final byte readByte() throws IOException { 265 int ch = in.read(); 266 if (ch < 0) 267 throw new EOFException(); 268 return (byte)(ch); 269 } 270 271 /** 272 * See the general contract of the <code>readUnsignedByte</code> 273 * method of <code>DataInput</code>. 274 * <p> 275 * Bytes 276 * for this operation are read from the contained 277 * input stream. 278 * 279 * @return the next byte of this input stream, interpreted as an 280 * unsigned 8-bit number. 281 * @exception EOFException if this input stream has reached the end. 282 * @exception IOException the stream has been closed and the contained 283 * input stream does not support reading after close, or 284 * another I/O error occurs. 285 * @see java.io.FilterInputStream#in 286 */ 287 public final int readUnsignedByte() throws IOException { 288 int ch = in.read(); 289 if (ch < 0) 290 throw new EOFException(); 291 return ch; 292 } 293 294 /** 295 * See the general contract of the <code>readShort</code> 296 * method of <code>DataInput</code>. 297 * <p> 298 * Bytes 299 * for this operation are read from the contained 300 * input stream. 301 * 302 * @return the next two bytes of this input stream, interpreted as a 303 * signed 16-bit number. 304 * @exception EOFException if this input stream reaches the end before 305 * reading two bytes. 306 * @exception IOException the stream has been closed and the contained 307 * input stream does not support reading after close, or 308 * another I/O error occurs. 309 * @see java.io.FilterInputStream#in 310 */ 311 public final short readShort() throws IOException { 312 int ch1 = in.read(); 313 int ch2 = in.read(); 314 if ((ch1 | ch2) < 0) 315 throw new EOFException(); 316 return (short)((ch1 << 8) + (ch2 << 0)); 317 } 318 319 /** 320 * See the general contract of the <code>readUnsignedShort</code> 321 * method of <code>DataInput</code>. 322 * <p> 323 * Bytes 324 * for this operation are read from the contained 325 * input stream. 326 * 327 * @return the next two bytes of this input stream, interpreted as an 328 * unsigned 16-bit integer. 329 * @exception EOFException if this input stream reaches the end before 330 * reading two bytes. 331 * @exception IOException the stream has been closed and the contained 332 * input stream does not support reading after close, or 333 * another I/O error occurs. 334 * @see java.io.FilterInputStream#in 335 */ 336 public final int readUnsignedShort() throws IOException { 337 int ch1 = in.read(); 338 int ch2 = in.read(); 339 if ((ch1 | ch2) < 0) 340 throw new EOFException(); 341 return (ch1 << 8) + (ch2 << 0); 342 } 343 344 /** 345 * See the general contract of the <code>readChar</code> 346 * method of <code>DataInput</code>. 347 * <p> 348 * Bytes 349 * for this operation are read from the contained 350 * input stream. 351 * 352 * @return the next two bytes of this input stream, interpreted as a 353 * <code>char</code>. 354 * @exception EOFException if this input stream reaches the end before 355 * reading two bytes. 356 * @exception IOException the stream has been closed and the contained 357 * input stream does not support reading after close, or 358 * another I/O error occurs. 359 * @see java.io.FilterInputStream#in 360 */ 361 public final char readChar() throws IOException { 362 int ch1 = in.read(); 363 int ch2 = in.read(); 364 if ((ch1 | ch2) < 0) 365 throw new EOFException(); 366 return (char)((ch1 << 8) + (ch2 << 0)); 367 } 368 369 /** 370 * See the general contract of the <code>readInt</code> 371 * method of <code>DataInput</code>. 372 * <p> 373 * Bytes 374 * for this operation are read from the contained 375 * input stream. 376 * 377 * @return the next four bytes of this input stream, interpreted as an 378 * <code>int</code>. 379 * @exception EOFException if this input stream reaches the end before 380 * reading four bytes. 381 * @exception IOException the stream has been closed and the contained 382 * input stream does not support reading after close, or 383 * another I/O error occurs. 384 * @see java.io.FilterInputStream#in 385 */ 386 public final int readInt() throws IOException { 387 int ch1 = in.read(); 388 int ch2 = in.read(); 389 int ch3 = in.read(); 390 int ch4 = in.read(); 391 if ((ch1 | ch2 | ch3 | ch4) < 0) 392 throw new EOFException(); 393 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); 394 } 395 396 private byte readBuffer[] = new byte[8]; 397 398 /** 399 * See the general contract of the <code>readLong</code> 400 * method of <code>DataInput</code>. 401 * <p> 402 * Bytes 403 * for this operation are read from the contained 404 * input stream. 405 * 406 * @return the next eight bytes of this input stream, interpreted as a 407 * <code>long</code>. 408 * @exception EOFException if this input stream reaches the end before 409 * reading eight bytes. 410 * @exception IOException the stream has been closed and the contained 411 * input stream does not support reading after close, or 412 * another I/O error occurs. 413 * @see java.io.FilterInputStream#in 414 */ 415 public final long readLong() throws IOException { 416 readFully(readBuffer, 0, 8); 417 return (((long)readBuffer[0] << 56) + 418 ((long)(readBuffer[1] & 255) << 48) + 419 ((long)(readBuffer[2] & 255) << 40) + 420 ((long)(readBuffer[3] & 255) << 32) + 421 ((long)(readBuffer[4] & 255) << 24) + 422 ((readBuffer[5] & 255) << 16) + 423 ((readBuffer[6] & 255) << 8) + 424 ((readBuffer[7] & 255) << 0)); 425 } 426 427 /** 428 * See the general contract of the <code>readFloat</code> 429 * method of <code>DataInput</code>. 430 * <p> 431 * Bytes 432 * for this operation are read from the contained 433 * input stream. 434 * 435 * @return the next four bytes of this input stream, interpreted as a 436 * <code>float</code>. 437 * @exception EOFException if this input stream reaches the end before 438 * reading four bytes. 439 * @exception IOException the stream has been closed and the contained 440 * input stream does not support reading after close, or 441 * another I/O error occurs. 442 * @see java.io.DataInputStream#readInt() 443 * @see java.lang.Float#intBitsToFloat(int) 444 */ 445 public final float readFloat() throws IOException { 446 return Float.intBitsToFloat(readInt()); 447 } 448 449 /** 450 * See the general contract of the <code>readDouble</code> 451 * method of <code>DataInput</code>. 452 * <p> 453 * Bytes 454 * for this operation are read from the contained 455 * input stream. 456 * 457 * @return the next eight bytes of this input stream, interpreted as a 458 * <code>double</code>. 459 * @exception EOFException if this input stream reaches the end before 460 * reading eight bytes. 461 * @exception IOException the stream has been closed and the contained 462 * input stream does not support reading after close, or 463 * another I/O error occurs. 464 * @see java.io.DataInputStream#readLong() 465 * @see java.lang.Double#longBitsToDouble(long) 466 */ 467 public final double readDouble() throws IOException { 468 return Double.longBitsToDouble(readLong()); 469 } 470 471 private char lineBuffer[]; 472 473 /** 474 * See the general contract of the <code>readLine</code> 475 * method of <code>DataInput</code>. 476 * <p> 477 * Bytes 478 * for this operation are read from the contained 479 * input stream. 480 * 481 * @deprecated This method does not properly convert bytes to characters. 482 * As of JDK 1.1, the preferred way to read lines of text is via the 483 * <code>BufferedReader.readLine()</code> method. Programs that use the 484 * <code>DataInputStream</code> class to read lines can be converted to use 485 * the <code>BufferedReader</code> class by replacing code of the form: 486 * <blockquote><pre> 487 * DataInputStream d = new DataInputStream(in); 488 * </pre></blockquote> 489 * with: 490 * <blockquote><pre> 491 * BufferedReader d 492 * = new BufferedReader(new InputStreamReader(in)); 493 * </pre></blockquote> 494 * 495 * @return the next line of text from this input stream. 496 * @exception IOException if an I/O error occurs. 497 * @see java.io.BufferedReader#readLine() 498 * @see java.io.FilterInputStream#in 499 */ 500 @Deprecated 501 public final String readLine() throws IOException { 502 char buf[] = lineBuffer; 503 504 if (buf == null) { 505 buf = lineBuffer = new char[128]; 506 } 507 508 int room = buf.length; 509 int offset = 0; 510 int c; 511 512loop: while (true) { 513 switch (c = in.read()) { 514 case -1: 515 case '\n': 516 break loop; 517 518 case '\r': 519 int c2 = in.read(); 520 if ((c2 != '\n') && (c2 != -1)) { 521 if (!(in instanceof PushbackInputStream)) { 522 this.in = new PushbackInputStream(in); 523 } 524 ((PushbackInputStream)in).unread(c2); 525 } 526 break loop; 527 528 default: 529 if (--room < 0) { 530 buf = new char[offset + 128]; 531 room = buf.length - offset - 1; 532 System.arraycopy(lineBuffer, 0, buf, 0, offset); 533 lineBuffer = buf; 534 } 535 buf[offset++] = (char) c; 536 break; 537 } 538 } 539 if ((c == -1) && (offset == 0)) { 540 return null; 541 } 542 return String.copyValueOf(buf, 0, offset); 543 } 544 545 /** 546 * See the general contract of the <code>readUTF</code> 547 * method of <code>DataInput</code>. 548 * <p> 549 * Bytes 550 * for this operation are read from the contained 551 * input stream. 552 * 553 * @return a Unicode string. 554 * @exception EOFException if this input stream reaches the end before 555 * reading all the bytes. 556 * @exception IOException the stream has been closed and the contained 557 * input stream does not support reading after close, or 558 * another I/O error occurs. 559 * @exception UTFDataFormatException if the bytes do not represent a valid 560 * modified UTF-8 encoding of a string. 561 * @see java.io.DataInputStream#readUTF(java.io.DataInput) 562 */ 563 public final String readUTF() throws IOException { 564 return readUTF(this); 565 } 566 567 /** 568 * Reads from the 569 * stream <code>in</code> a representation 570 * of a Unicode character string encoded in 571 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format; 572 * this string of characters is then returned as a <code>String</code>. 573 * The details of the modified UTF-8 representation 574 * are exactly the same as for the <code>readUTF</code> 575 * method of <code>DataInput</code>. 576 * 577 * @param in a data input stream. 578 * @return a Unicode string. 579 * @exception EOFException if the input stream reaches the end 580 * before all the bytes. 581 * @exception IOException the stream has been closed and the contained 582 * input stream does not support reading after close, or 583 * another I/O error occurs. 584 * @exception UTFDataFormatException if the bytes do not represent a 585 * valid modified UTF-8 encoding of a Unicode string. 586 * @see java.io.DataInputStream#readUnsignedShort() 587 */ 588 public final static String readUTF(DataInput in) throws IOException { 589 int utflen = in.readUnsignedShort(); 590 byte[] bytearr = null; 591 char[] chararr = null; 592 if (in instanceof DataInputStream) { 593 DataInputStream dis = (DataInputStream)in; 594 if (dis.bytearr.length < utflen){ 595 dis.bytearr = new byte[utflen*2]; 596 dis.chararr = new char[utflen*2]; 597 } 598 chararr = dis.chararr; 599 bytearr = dis.bytearr; 600 } else { 601 bytearr = new byte[utflen]; 602 chararr = new char[utflen]; 603 } 604 605 int c, char2, char3; 606 int count = 0; 607 int chararr_count=0; 608 609 in.readFully(bytearr, 0, utflen); 610 611 while (count < utflen) { 612 c = (int) bytearr[count] & 0xff; 613 if (c > 127) break; 614 count++; 615 chararr[chararr_count++]=(char)c; 616 } 617 618 while (count < utflen) { 619 c = (int) bytearr[count] & 0xff; 620 switch (c >> 4) { 621 case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: 622 /* 0xxxxxxx*/ 623 count++; 624 chararr[chararr_count++]=(char)c; 625 break; 626 case 12: case 13: 627 /* 110x xxxx 10xx xxxx*/ 628 count += 2; 629 if (count > utflen) 630 throw new UTFDataFormatException( 631 "malformed input: partial character at end"); 632 char2 = (int) bytearr[count-1]; 633 if ((char2 & 0xC0) != 0x80) 634 throw new UTFDataFormatException( 635 "malformed input around byte " + count); 636 chararr[chararr_count++]=(char)(((c & 0x1F) << 6) | 637 (char2 & 0x3F)); 638 break; 639 case 14: 640 /* 1110 xxxx 10xx xxxx 10xx xxxx */ 641 count += 3; 642 if (count > utflen) 643 throw new UTFDataFormatException( 644 "malformed input: partial character at end"); 645 char2 = (int) bytearr[count-2]; 646 char3 = (int) bytearr[count-1]; 647 if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80)) 648 throw new UTFDataFormatException( 649 "malformed input around byte " + (count-1)); 650 chararr[chararr_count++]=(char)(((c & 0x0F) << 12) | 651 ((char2 & 0x3F) << 6) | 652 ((char3 & 0x3F) << 0)); 653 break; 654 default: 655 /* 10xx xxxx, 1111 xxxx */ 656 throw new UTFDataFormatException( 657 "malformed input around byte " + count); 658 } 659 } 660 // The number of chars produced may be less than utflen 661 return new String(chararr, 0, chararr_count); 662 } 663} 664