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
26 package 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 */
42 public
43 class 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
517 loop: 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 }