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
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</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
512 loop: 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 }