1/* 2 * Copyright (c) 1994, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 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 1.0 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} 154 * method of {@code DataInput}. 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 * @throws NullPointerException if {@code b} is {@code null}. 162 * @throws EOFException if this input stream reaches the end before 163 * reading all the bytes. 164 * @throws IOException the stream has been closed and the contained 165 * input stream does not support reading after close, or 166 * another I/O error occurs. 167 * @see java.io.FilterInputStream#in 168 */ 169 public final void readFully(byte b[]) throws IOException { 170 readFully(b, 0, b.length); 171 } 172 173 /** 174 * See the general contract of the {@code readFully} 175 * method of {@code DataInput}. 176 * <p> 177 * Bytes 178 * for this operation are read from the contained 179 * input stream. 180 * 181 * @param b the buffer into which the data is read. 182 * @param off the start offset in the data array {@code b}. 183 * @param len the number of bytes to read. 184 * @exception NullPointerException if {@code b} is {@code null}. 185 * @exception IndexOutOfBoundsException if {@code off} is negative, 186 * {@code len} is negative, or {@code len} is greater than 187 * {@code b.length - off}. 188 * @exception EOFException if this input stream reaches the end before 189 * reading all the bytes. 190 * @exception IOException the stream has been closed and the contained 191 * input stream does not support reading after close, or 192 * another I/O error occurs. 193 * @see java.io.FilterInputStream#in 194 */ 195 public final void readFully(byte b[], int off, int len) throws IOException { 196 if (len < 0) 197 throw new IndexOutOfBoundsException(); 198 int n = 0; 199 while (n < len) { 200 int count = in.read(b, off + n, len - n); 201 if (count < 0) 202 throw new EOFException(); 203 n += count; 204 } 205 } 206 207 /** 208 * See the general contract of the <code>skipBytes</code> 209 * method of <code>DataInput</code>. 210 * <p> 211 * Bytes for this operation are read from the contained 212 * input stream. 213 * 214 * @param n the number of bytes to be skipped. 215 * @return the actual number of bytes skipped. 216 * @exception IOException if the contained input stream does not support 217 * seek, or the stream has been closed and 218 * the contained input stream does not support 219 * reading after close, or another I/O error occurs. 220 */ 221 public final int skipBytes(int n) throws IOException { 222 int total = 0; 223 int cur = 0; 224 225 while ((total<n) && ((cur = (int) in.skip(n-total)) > 0)) { 226 total += cur; 227 } 228 229 return total; 230 } 231 232 /** 233 * See the general contract of the <code>readBoolean</code> 234 * method of <code>DataInput</code>. 235 * <p> 236 * Bytes for this operation are read from the contained 237 * input stream. 238 * 239 * @return the <code>boolean</code> value read. 240 * @exception EOFException if this input stream has reached the end. 241 * @exception IOException the stream has been closed and the contained 242 * input stream does not support reading after close, or 243 * another I/O error occurs. 244 * @see java.io.FilterInputStream#in 245 */ 246 public final boolean readBoolean() throws IOException { 247 int ch = in.read(); 248 if (ch < 0) 249 throw new EOFException(); 250 return (ch != 0); 251 } 252 253 /** 254 * See the general contract of the <code>readByte</code> 255 * method of <code>DataInput</code>. 256 * <p> 257 * Bytes 258 * for this operation are read from the contained 259 * input stream. 260 * 261 * @return the next byte of this input stream as a signed 8-bit 262 * <code>byte</code>. 263 * @exception EOFException if this input stream has reached the end. 264 * @exception IOException the stream has been closed and the contained 265 * input stream does not support reading after close, or 266 * another I/O error occurs. 267 * @see java.io.FilterInputStream#in 268 */ 269 public final byte readByte() throws IOException { 270 int ch = in.read(); 271 if (ch < 0) 272 throw new EOFException(); 273 return (byte)(ch); 274 } 275 276 /** 277 * See the general contract of the <code>readUnsignedByte</code> 278 * method of <code>DataInput</code>. 279 * <p> 280 * Bytes 281 * for this operation are read from the contained 282 * input stream. 283 * 284 * @return the next byte of this input stream, interpreted as an 285 * unsigned 8-bit number. 286 * @exception EOFException if this input stream has reached the end. 287 * @exception IOException the stream has been closed and the contained 288 * input stream does not support reading after close, or 289 * another I/O error occurs. 290 * @see java.io.FilterInputStream#in 291 */ 292 public final int readUnsignedByte() throws IOException { 293 int ch = in.read(); 294 if (ch < 0) 295 throw new EOFException(); 296 return ch; 297 } 298 299 /** 300 * See the general contract of the <code>readShort</code> 301 * method of <code>DataInput</code>. 302 * <p> 303 * Bytes 304 * for this operation are read from the contained 305 * input stream. 306 * 307 * @return the next two bytes of this input stream, interpreted as a 308 * signed 16-bit number. 309 * @exception EOFException if this input stream reaches the end before 310 * reading two bytes. 311 * @exception IOException the stream has been closed and the contained 312 * input stream does not support reading after close, or 313 * another I/O error occurs. 314 * @see java.io.FilterInputStream#in 315 */ 316 public final short readShort() throws IOException { 317 int ch1 = in.read(); 318 int ch2 = in.read(); 319 if ((ch1 | ch2) < 0) 320 throw new EOFException(); 321 return (short)((ch1 << 8) + (ch2 << 0)); 322 } 323 324 /** 325 * See the general contract of the <code>readUnsignedShort</code> 326 * method of <code>DataInput</code>. 327 * <p> 328 * Bytes 329 * for this operation are read from the contained 330 * input stream. 331 * 332 * @return the next two bytes of this input stream, interpreted as an 333 * unsigned 16-bit integer. 334 * @exception EOFException if this input stream reaches the end before 335 * reading two bytes. 336 * @exception IOException the stream has been closed and the contained 337 * input stream does not support reading after close, or 338 * another I/O error occurs. 339 * @see java.io.FilterInputStream#in 340 */ 341 public final int readUnsignedShort() throws IOException { 342 int ch1 = in.read(); 343 int ch2 = in.read(); 344 if ((ch1 | ch2) < 0) 345 throw new EOFException(); 346 return (ch1 << 8) + (ch2 << 0); 347 } 348 349 /** 350 * See the general contract of the <code>readChar</code> 351 * method of <code>DataInput</code>. 352 * <p> 353 * Bytes 354 * for this operation are read from the contained 355 * input stream. 356 * 357 * @return the next two bytes of this input stream, interpreted as a 358 * <code>char</code>. 359 * @exception EOFException if this input stream reaches the end before 360 * reading two bytes. 361 * @exception IOException the stream has been closed and the contained 362 * input stream does not support reading after close, or 363 * another I/O error occurs. 364 * @see java.io.FilterInputStream#in 365 */ 366 public final char readChar() throws IOException { 367 int ch1 = in.read(); 368 int ch2 = in.read(); 369 if ((ch1 | ch2) < 0) 370 throw new EOFException(); 371 return (char)((ch1 << 8) + (ch2 << 0)); 372 } 373 374 /** 375 * See the general contract of the <code>readInt</code> 376 * method of <code>DataInput</code>. 377 * <p> 378 * Bytes 379 * for this operation are read from the contained 380 * input stream. 381 * 382 * @return the next four bytes of this input stream, interpreted as an 383 * <code>int</code>. 384 * @exception EOFException if this input stream reaches the end before 385 * reading four bytes. 386 * @exception IOException the stream has been closed and the contained 387 * input stream does not support reading after close, or 388 * another I/O error occurs. 389 * @see java.io.FilterInputStream#in 390 */ 391 public final int readInt() throws IOException { 392 int ch1 = in.read(); 393 int ch2 = in.read(); 394 int ch3 = in.read(); 395 int ch4 = in.read(); 396 if ((ch1 | ch2 | ch3 | ch4) < 0) 397 throw new EOFException(); 398 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); 399 } 400 401 private byte readBuffer[] = new byte[8]; 402 403 /** 404 * See the general contract of the <code>readLong</code> 405 * method of <code>DataInput</code>. 406 * <p> 407 * Bytes 408 * for this operation are read from the contained 409 * input stream. 410 * 411 * @return the next eight bytes of this input stream, interpreted as a 412 * <code>long</code>. 413 * @exception EOFException if this input stream reaches the end before 414 * reading eight bytes. 415 * @exception IOException the stream has been closed and the contained 416 * input stream does not support reading after close, or 417 * another I/O error occurs. 418 * @see java.io.FilterInputStream#in 419 */ 420 public final long readLong() throws IOException { 421 readFully(readBuffer, 0, 8); 422 return (((long)readBuffer[0] << 56) + 423 ((long)(readBuffer[1] & 255) << 48) + 424 ((long)(readBuffer[2] & 255) << 40) + 425 ((long)(readBuffer[3] & 255) << 32) + 426 ((long)(readBuffer[4] & 255) << 24) + 427 ((readBuffer[5] & 255) << 16) + 428 ((readBuffer[6] & 255) << 8) + 429 ((readBuffer[7] & 255) << 0)); 430 } 431 432 /** 433 * See the general contract of the <code>readFloat</code> 434 * method of <code>DataInput</code>. 435 * <p> 436 * Bytes 437 * for this operation are read from the contained 438 * input stream. 439 * 440 * @return the next four bytes of this input stream, interpreted as a 441 * <code>float</code>. 442 * @exception EOFException if this input stream reaches the end before 443 * reading four bytes. 444 * @exception IOException the stream has been closed and the contained 445 * input stream does not support reading after close, or 446 * another I/O error occurs. 447 * @see java.io.DataInputStream#readInt() 448 * @see java.lang.Float#intBitsToFloat(int) 449 */ 450 public final float readFloat() throws IOException { 451 return Float.intBitsToFloat(readInt()); 452 } 453 454 /** 455 * See the general contract of the <code>readDouble</code> 456 * method of <code>DataInput</code>. 457 * <p> 458 * Bytes 459 * for this operation are read from the contained 460 * input stream. 461 * 462 * @return the next eight bytes of this input stream, interpreted as a 463 * <code>double</code>. 464 * @exception EOFException if this input stream reaches the end before 465 * reading eight bytes. 466 * @exception IOException the stream has been closed and the contained 467 * input stream does not support reading after close, or 468 * another I/O error occurs. 469 * @see java.io.DataInputStream#readLong() 470 * @see java.lang.Double#longBitsToDouble(long) 471 */ 472 public final double readDouble() throws IOException { 473 return Double.longBitsToDouble(readLong()); 474 } 475 476 private char lineBuffer[]; 477 478 /** 479 * See the general contract of the <code>readLine</code> 480 * method of <code>DataInput</code>. 481 * <p> 482 * Bytes 483 * for this operation are read from the contained 484 * input stream. 485 * 486 * @deprecated This method does not properly convert bytes to characters. 487 * As of JDK 1.1, the preferred way to read lines of text is via the 488 * <code>BufferedReader.readLine()</code> method. Programs that use the 489 * <code>DataInputStream</code> class to read lines can be converted to use 490 * the <code>BufferedReader</code> class by replacing code of the form: 491 * <blockquote><pre> 492 * DataInputStream d = new DataInputStream(in); 493 * </pre></blockquote> 494 * with: 495 * <blockquote><pre> 496 * BufferedReader d 497 * = new BufferedReader(new InputStreamReader(in)); 498 * </pre></blockquote> 499 * 500 * @return the next line of text from this input stream. 501 * @exception IOException if an I/O error occurs. 502 * @see java.io.BufferedReader#readLine() 503 * @see java.io.FilterInputStream#in 504 */ 505 @Deprecated 506 public final String readLine() throws IOException { 507 char buf[] = lineBuffer; 508 509 if (buf == null) { 510 buf = lineBuffer = new char[128]; 511 } 512 513 int room = buf.length; 514 int offset = 0; 515 int c; 516 517loop: while (true) { 518 switch (c = in.read()) { 519 case -1: 520 case '\n': 521 break loop; 522 523 case '\r': 524 int c2 = in.read(); 525 if ((c2 != '\n') && (c2 != -1)) { 526 if (!(in instanceof PushbackInputStream)) { 527 this.in = new PushbackInputStream(in); 528 } 529 ((PushbackInputStream)in).unread(c2); 530 } 531 break loop; 532 533 default: 534 if (--room < 0) { 535 buf = new char[offset + 128]; 536 room = buf.length - offset - 1; 537 System.arraycopy(lineBuffer, 0, buf, 0, offset); 538 lineBuffer = buf; 539 } 540 buf[offset++] = (char) c; 541 break; 542 } 543 } 544 if ((c == -1) && (offset == 0)) { 545 return null; 546 } 547 return String.copyValueOf(buf, 0, offset); 548 } 549 550 /** 551 * See the general contract of the <code>readUTF</code> 552 * method of <code>DataInput</code>. 553 * <p> 554 * Bytes 555 * for this operation are read from the contained 556 * input stream. 557 * 558 * @return a Unicode string. 559 * @exception EOFException if this input stream reaches the end before 560 * reading all the bytes. 561 * @exception IOException the stream has been closed and the contained 562 * input stream does not support reading after close, or 563 * another I/O error occurs. 564 * @exception UTFDataFormatException if the bytes do not represent a valid 565 * modified UTF-8 encoding of a string. 566 * @see java.io.DataInputStream#readUTF(java.io.DataInput) 567 */ 568 public final String readUTF() throws IOException { 569 return readUTF(this); 570 } 571 572 /** 573 * Reads from the 574 * stream <code>in</code> a representation 575 * of a Unicode character string encoded in 576 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format; 577 * this string of characters is then returned as a <code>String</code>. 578 * The details of the modified UTF-8 representation 579 * are exactly the same as for the <code>readUTF</code> 580 * method of <code>DataInput</code>. 581 * 582 * @param in a data input stream. 583 * @return a Unicode string. 584 * @exception EOFException if the input stream reaches the end 585 * before all the bytes. 586 * @exception IOException the stream has been closed and the contained 587 * input stream does not support reading after close, or 588 * another I/O error occurs. 589 * @exception UTFDataFormatException if the bytes do not represent a 590 * valid modified UTF-8 encoding of a Unicode string. 591 * @see java.io.DataInputStream#readUnsignedShort() 592 */ 593 public static final String readUTF(DataInput in) throws IOException { 594 int utflen = in.readUnsignedShort(); 595 byte[] bytearr = null; 596 char[] chararr = null; 597 if (in instanceof DataInputStream) { 598 DataInputStream dis = (DataInputStream)in; 599 if (dis.bytearr.length < utflen){ 600 dis.bytearr = new byte[utflen*2]; 601 dis.chararr = new char[utflen*2]; 602 } 603 chararr = dis.chararr; 604 bytearr = dis.bytearr; 605 } else { 606 bytearr = new byte[utflen]; 607 chararr = new char[utflen]; 608 } 609 610 int c, char2, char3; 611 int count = 0; 612 int chararr_count=0; 613 614 in.readFully(bytearr, 0, utflen); 615 616 while (count < utflen) { 617 c = (int) bytearr[count] & 0xff; 618 if (c > 127) break; 619 count++; 620 chararr[chararr_count++]=(char)c; 621 } 622 623 while (count < utflen) { 624 c = (int) bytearr[count] & 0xff; 625 switch (c >> 4) { 626 case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: 627 /* 0xxxxxxx*/ 628 count++; 629 chararr[chararr_count++]=(char)c; 630 break; 631 case 12: case 13: 632 /* 110x xxxx 10xx xxxx*/ 633 count += 2; 634 if (count > utflen) 635 throw new UTFDataFormatException( 636 "malformed input: partial character at end"); 637 char2 = (int) bytearr[count-1]; 638 if ((char2 & 0xC0) != 0x80) 639 throw new UTFDataFormatException( 640 "malformed input around byte " + count); 641 chararr[chararr_count++]=(char)(((c & 0x1F) << 6) | 642 (char2 & 0x3F)); 643 break; 644 case 14: 645 /* 1110 xxxx 10xx xxxx 10xx xxxx */ 646 count += 3; 647 if (count > utflen) 648 throw new UTFDataFormatException( 649 "malformed input: partial character at end"); 650 char2 = (int) bytearr[count-2]; 651 char3 = (int) bytearr[count-1]; 652 if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80)) 653 throw new UTFDataFormatException( 654 "malformed input around byte " + (count-1)); 655 chararr[chararr_count++]=(char)(((c & 0x0F) << 12) | 656 ((char2 & 0x3F) << 6) | 657 ((char3 & 0x3F) << 0)); 658 break; 659 default: 660 /* 10xx xxxx, 1111 xxxx */ 661 throw new UTFDataFormatException( 662 "malformed input around byte " + count); 663 } 664 } 665 // The number of chars produced may be less than utflen 666 return new String(chararr, 0, chararr_count); 667 } 668} 669