1 package org.apache.maven.shared.utils.io;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import javax.annotation.Nonnull;
23 import javax.annotation.Nullable;
24
25 import java.io.BufferedInputStream;
26 import java.io.ByteArrayInputStream;
27 import java.io.ByteArrayOutputStream;
28 import java.io.IOException;
29 import java.io.InputStream;
30 import java.io.InputStreamReader;
31 import java.io.OutputStream;
32 import java.io.OutputStreamWriter;
33 import java.io.Reader;
34 import java.io.StringReader;
35 import java.io.StringWriter;
36 import java.io.Writer;
37 import java.nio.channels.Channel;
38
39 /**
40 * General IO Stream manipulation.
41 * <p>
42 * This class provides static utility methods for input/output operations, particularly buffered
43 * copying between sources (<code>InputStream</code>, <code>Reader</code>, <code>String</code> and
44 * <code>byte[]</code>) and destinations (<code>OutputStream</code>, <code>Writer</code>,
45 * <code>String</code> and <code>byte[]</code>).
46 * </p>
47 * <p/>
48 * <p>Unless otherwise noted, these <code>copy</code> methods do <em>not</em> flush or close the
49 * streams. Often, doing so would require making non-portable assumptions about the streams' origin
50 * and further use. This means that both streams' <code>close()</code> methods must be called after
51 * copying. if one omits this step, then the stream resources (sockets, file descriptors) are
52 * released when the associated Stream is garbage-collected. It is not a good idea to rely on this
53 * mechanism. For a good overview of the distinction between "memory management" and "resource
54 * management", see <a href="http://www.unixreview.com/articles/1998/9804/9804ja/ja.htm">this
55 * UnixReview article</a></p>
56 * <p/>
57 * <p>For each <code>copy</code> method, a variant is provided that allows the caller to specify the
58 * buffer size (the default is 4k). As the buffer size can have a fairly large impact on speed, this
59 * may be worth tweaking. Often "large buffer -> faster" does not hold, even for large data
60 * transfers.</p>
61 * <p/>
62 * <p>For byte-to-char methods, a <code>copy</code> variant allows the encoding to be selected
63 * (otherwise the platform default is used).</p>
64 * <p/>
65 * <p>The <code>copy</code> methods use an internal buffer when copying. It is therefore advisable
66 * <em>not</em> to deliberately wrap the stream arguments to the <code>copy</code> methods in
67 * <code>Buffered*</code> streams. For example, don't do the
68 * following:</p>
69 * <p/>
70 * <code>copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );</code>
71 * <p/>
72 * <p>The rationale is as follows:</p>
73 * <p/>
74 * <p>Imagine that an InputStream's read() is a very expensive operation, which would usually suggest
75 * wrapping in a BufferedInputStream. The BufferedInputStream works by issuing infrequent
76 * {@link java.io.InputStream#read(byte[] b, int off, int len)} requests on the underlying InputStream, to
77 * fill an internal buffer, from which further <code>read</code> requests can inexpensively get
78 * their data (until the buffer runs out).</p>
79 * <p>However, the <code>copy</code> methods do the same thing, keeping an internal buffer,
80 * populated by {@link InputStream#read(byte[] b, int off, int len)} requests. Having two buffers
81 * (or three if the destination stream is also buffered) is pointless, and the unnecessary buffer
82 * management hurts performance slightly (about 3%, according to some simple experiments).</p>
83 *
84 * @author <a href="mailto:peter@apache.org">Peter Donald</a>
85 * @author <a href="mailto:jefft@apache.org">Jeff Turner</a>
86 * @version CVS $Revision: 1750548 $ $Date: 2016-06-28 19:32:21 +0200 (Tue, 28 Jun 2016) $
87 *
88 */
89 public final class IOUtil
90 /*
91 * Behold, intrepid explorers; a map of this class:
92 *
93 * Method Input Output Dependency
94 * ------ ----- ------ -------
95 * 1 copy InputStream OutputStream (primitive)
96 * 2 copy Reader Writer (primitive)
97 *
98 * 3 copy InputStream Writer 2
99 * 4 toString InputStream String 3
100 * 5 toByteArray InputStream byte[] 1
101 *
102 * 6 copy Reader OutputStream 2
103 * 7 toString Reader String 2
104 * 8 toByteArray Reader byte[] 6
105 *
106 * 9 copy String OutputStream 2
107 * 10 copy String Writer (trivial)
108 * 11 toByteArray String byte[] 9
109 *
110 * 12 copy byte[] Writer 3
111 * 13 toString byte[] String 12
112 * 14 copy byte[] OutputStream (trivial)
113 *
114 *
115 * Note that only the first two methods shuffle bytes; the rest use these two, or (if possible) copy
116 * using native Java copy methods. As there are method variants to specify buffer size and encoding,
117 * each row may correspond to up to 4 methods.
118 *
119 */
120 {
121 private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;
122
123 /**
124 * Private constructor to prevent instantiation.
125 */
126 private IOUtil()
127 {
128 }
129
130 ///////////////////////////////////////////////////////////////
131 // Core copy methods
132 ///////////////////////////////////////////////////////////////
133
134 /**
135 * Copy bytes from an <code>InputStream</code> to an <code>OutputStream</code>.
136 * @param input The input size.
137 * @param output The resulting output.
138 * @throws IOException in case of an error.
139 */
140 public static void copy( @Nonnull final InputStream input, @Nonnull final OutputStream output )
141 throws IOException
142 {
143 copy( input, output, DEFAULT_BUFFER_SIZE );
144 }
145
146 /**
147 * Copy bytes from an <code>InputStream</code> to an <code>OutputStream</code>.
148 *
149 * @param input The input size.
150 * @param output The resulting output.
151 * @param bufferSize Size of internal buffer to use.
152 * @throws IOException in case of an error.
153 */
154 public static void copy( @Nonnull final InputStream input, @Nonnull final OutputStream output,
155 final int bufferSize )
156 throws IOException
157 {
158 final byte[] buffer = new byte[bufferSize];
159 int n;
160 while ( -1 != ( n = input.read( buffer ) ) )
161 {
162 output.write( buffer, 0, n );
163 }
164 }
165
166 /**
167 * Copy chars from a <code>Reader</code> to a <code>Writer</code>.
168 * @param input The input size.
169 * @param output The resulting output.
170 * @throws IOException in case of failure.
171 */
172 public static void copy( @Nonnull final Reader input, @Nonnull final Writer output )
173 throws IOException
174 {
175 copy( input, output, DEFAULT_BUFFER_SIZE );
176 }
177
178 /**
179 * Copy chars from a <code>Reader</code> to a <code>Writer</code>.
180 *
181 * @param input The input size.
182 * @param output The resulting output.
183 * @param bufferSize Size of internal buffer to use.
184 * @throws IOException in case of failure.
185 */
186 public static void copy( @Nonnull final Reader input, @Nonnull final Writer output, final int bufferSize )
187 throws IOException
188 {
189 final char[] buffer = new char[bufferSize];
190 int n;
191 while ( -1 != ( n = input.read( buffer ) ) )
192 {
193 output.write( buffer, 0, n );
194 }
195 output.flush();
196 }
197
198 ///////////////////////////////////////////////////////////////
199 // Derived copy methods
200 // InputStream -> *
201 ///////////////////////////////////////////////////////////////
202
203 ///////////////////////////////////////////////////////////////
204 // InputStream -> Writer
205
206 /**
207 * Copy and convert bytes from an <code>InputStream</code> to chars on a
208 * <code>Writer</code>.
209 * The platform's default encoding is used for the byte-to-char conversion.
210 * @param input The input size.
211 * @param output The resulting output.
212 * @throws IOException in case of failure.
213 */
214 public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output )
215 throws IOException
216 {
217 copy( input, output, DEFAULT_BUFFER_SIZE );
218 }
219
220 /**
221 * Copy and convert bytes from an <code>InputStream</code> to chars on a
222 * <code>Writer</code>.
223 * The platform's default encoding is used for the byte-to-char conversion.
224 *
225 * @param input The input size.
226 * @param output The resulting output.
227 * @param bufferSize Size of internal buffer to use.
228 * @throws IOException in case of failure.
229 */
230 public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output, final int bufferSize )
231 throws IOException
232 {
233 final InputStreamReader in = new InputStreamReader( input );
234 copy( in, output, bufferSize );
235 }
236
237 /**
238 * Copy and convert bytes from an <code>InputStream</code> to chars on a
239 * <code>Writer</code>, using the specified encoding.
240 *
241 * @param input The input size.
242 * @param output The resulting output.
243 * @param encoding The name of a supported character encoding. See the
244 * <a href="http://www.iana.org/assignments/character-sets">IANA
245 * Charset Registry</a> for a list of valid encoding types.
246 * @throws IOException in case of failure.
247 */
248 public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output,
249 @Nonnull final String encoding )
250 throws IOException
251 {
252 final InputStreamReader in = new InputStreamReader( input, encoding );
253 copy( in, output );
254 }
255
256 /**
257 * Copy and convert bytes from an <code>InputStream</code> to chars on a
258 * <code>Writer</code>, using the specified encoding.
259 *
260 * @param encoding The name of a supported character encoding. See the
261 * <a href="http://www.iana.org/assignments/character-sets">IANA
262 * Charset Registry</a> for a list of valid encoding types.
263 * @param input The input size.
264 * @param output The resulting output.
265 * @param bufferSize Size of internal buffer to use.
266 * @throws IOException in case of failure.
267 */
268 public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output,
269 @Nonnull final String encoding, final int bufferSize )
270 throws IOException
271 {
272 final InputStreamReader in = new InputStreamReader( input, encoding );
273 copy( in, output, bufferSize );
274 }
275
276 ///////////////////////////////////////////////////////////////
277 // InputStream -> String
278
279 /**
280 * Get the contents of an <code>InputStream</code> as a String.
281 * The platform's default encoding is used for the byte-to-char conversion.
282 * @param input The input size.
283 * @return The resulting string.
284 * @throws IOException in case of failure.
285 */
286 @Nonnull public static String toString( @Nonnull final InputStream input )
287 throws IOException
288 {
289 return toString( input, DEFAULT_BUFFER_SIZE );
290 }
291
292 /**
293 * Get the contents of an <code>InputStream</code> as a String.
294 * The platform's default encoding is used for the byte-to-char conversion.
295 *
296 * @param input The input size.
297 * @param bufferSize Size of internal buffer to use.
298 * @return the resulting string.
299 * @throws IOException in case of failure.
300 */
301 @Nonnull public static String toString( @Nonnull final InputStream input, final int bufferSize )
302 throws IOException
303 {
304 final StringWriter sw = new StringWriter();
305 copy( input, sw, bufferSize );
306 return sw.toString();
307 }
308
309 /**
310 * Get the contents of an <code>InputStream</code> as a String.
311 *
312 * @param input The input size.
313 * @param encoding The name of a supported character encoding. See the
314 * <a href="http://www.iana.org/assignments/character-sets">IANA
315 * Charset Registry</a> for a list of valid encoding types.
316 * @return the converted string.
317 * @throws IOException in case of failure.
318 */
319 @Nonnull public static String toString( @Nonnull final InputStream input, @Nonnull final String encoding )
320 throws IOException
321 {
322 return toString( input, encoding, DEFAULT_BUFFER_SIZE );
323 }
324
325 /**
326 * Get the contents of an <code>InputStream</code> as a String.
327 *
328 * @param input The input size.
329 * @param encoding The name of a supported character encoding. See the
330 * <a href="http://www.iana.org/assignments/character-sets">IANA
331 * Charset Registry</a> for a list of valid encoding types.
332 * @param bufferSize Size of internal buffer to use.
333 * @return The converted string.
334 * @throws IOException in case of failure.
335 */
336 @Nonnull public static String toString( @Nonnull final InputStream input, @Nonnull final String encoding,
337 final int bufferSize )
338 throws IOException
339 {
340 final StringWriter sw = new StringWriter();
341 copy( input, sw, encoding, bufferSize );
342 return sw.toString();
343 }
344
345 ///////////////////////////////////////////////////////////////
346 // InputStream -> byte[]
347
348 /**
349 * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>.
350 * @param input The input size.
351 * @return the resulting byte array.
352 * @throws IOException in case of failure.
353 */
354 @Nonnull public static byte[] toByteArray( @Nonnull final InputStream input )
355 throws IOException
356 {
357 return toByteArray( input, DEFAULT_BUFFER_SIZE );
358 }
359
360 /**
361 * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>.
362 *
363 * @param input The input size.
364 * @param bufferSize Size of internal buffer to use.
365 * @return the resulting byte array.
366 * @throws IOException in case of failure.
367 */
368 @Nonnull public static byte[] toByteArray( @Nonnull final InputStream input, final int bufferSize )
369 throws IOException
370 {
371 final ByteArrayOutputStream output = new ByteArrayOutputStream();
372 copy( input, output, bufferSize );
373 return output.toByteArray();
374 }
375
376 ///////////////////////////////////////////////////////////////
377 // Derived copy methods
378 // Reader -> *
379 ///////////////////////////////////////////////////////////////
380
381 ///////////////////////////////////////////////////////////////
382 // Reader -> OutputStream
383
384 /**
385 * Serialize chars from a <code>Reader</code> to bytes on an <code>OutputStream</code>, and
386 * flush the <code>OutputStream</code>.
387 * @param input The input size.
388 * @param output The resulting output.
389 * @throws IOException in case of failure.
390 */
391 public static void copy( @Nonnull final Reader input, @Nonnull final OutputStream output )
392 throws IOException
393 {
394 copy( input, output, DEFAULT_BUFFER_SIZE );
395 }
396
397 /**
398 * Serialize chars from a <code>Reader</code> to bytes on an <code>OutputStream</code>, and
399 * flush the <code>OutputStream</code>.
400 *
401 * @param input The input size.
402 * @param output The resulting output.
403 * @param bufferSize Size of internal buffer to use.
404 * @throws IOException in case of failure.
405 */
406 public static void copy( @Nonnull final Reader input, @Nonnull final OutputStream output, final int bufferSize )
407 throws IOException
408 {
409 final OutputStreamWriter out = new OutputStreamWriter( output );
410 copy( input, out, bufferSize );
411 // NOTE: Unless anyone is planning on rewriting OutputStreamWriter, we have to flush
412 // here.
413 out.flush();
414 }
415
416 ///////////////////////////////////////////////////////////////
417 // Reader -> String
418
419 /**
420 * Get the contents of a <code>Reader</code> as a String.
421 * @param input The input size.
422 * @return The converted string.
423 * @throws IOException in case of failure.
424 */
425 @Nonnull public static String toString( @Nonnull final Reader input )
426 throws IOException
427 {
428 return toString( input, DEFAULT_BUFFER_SIZE );
429 }
430
431 /**
432 * Get the contents of a <code>Reader</code> as a String.
433 *
434 * @param input The input size.
435 * @param bufferSize Size of internal buffer to use.
436 * @return the resulting byte array.
437 * @throws IOException in case of failure.
438 */
439 @Nonnull public static String toString( @Nonnull final Reader input, final int bufferSize )
440 throws IOException
441 {
442 final StringWriter sw = new StringWriter();
443 copy( input, sw, bufferSize );
444 return sw.toString();
445 }
446
447 ///////////////////////////////////////////////////////////////
448 // Reader -> byte[]
449
450 /**
451 * Get the contents of a <code>Reader</code> as a <code>byte[]</code>.
452 * @param input The input size.
453 * @return the resulting byte array.
454 * @throws IOException in case of failure.
455 */
456 @Nonnull public static byte[] toByteArray( @Nonnull final Reader input )
457 throws IOException
458 {
459 return toByteArray( input, DEFAULT_BUFFER_SIZE );
460 }
461
462 /**
463 * Get the contents of a <code>Reader</code> as a <code>byte[]</code>.
464 *
465 * @param input The input size.
466 * @param bufferSize Size of internal buffer to use.
467 * @return the resulting byte array.
468 * @throws IOException in case of failure.
469 */
470 @Nonnull public static byte[] toByteArray( @Nonnull final Reader input, final int bufferSize )
471 throws IOException
472 {
473 ByteArrayOutputStream output = new ByteArrayOutputStream();
474 copy( input, output, bufferSize );
475 return output.toByteArray();
476 }
477
478 ///////////////////////////////////////////////////////////////
479 // Derived copy methods
480 // String -> *
481 ///////////////////////////////////////////////////////////////
482
483 ///////////////////////////////////////////////////////////////
484 // String -> OutputStream
485
486 /**
487 * Serialize chars from a <code>String</code> to bytes on an <code>OutputStream</code>, and
488 * flush the <code>OutputStream</code>.
489 * @param input The input size.
490 * @param output The resulting output.
491 * @throws IOException in case of failure.
492 */
493 public static void copy( @Nonnull final String input, @Nonnull final OutputStream output )
494 throws IOException
495 {
496 copy( input, output, DEFAULT_BUFFER_SIZE );
497 }
498
499 /**
500 * Serialize chars from a <code>String</code> to bytes on an <code>OutputStream</code>, and
501 * flush the <code>OutputStream</code>.
502 *
503 * @param input The input size.
504 * @param output The resulting output.
505 * @param bufferSize Size of internal buffer to use.
506 * @throws IOException in case of failure.
507 */
508 public static void copy( @Nonnull final String input, @Nonnull final OutputStream output, final int bufferSize )
509 throws IOException
510 {
511 final StringReader in = new StringReader( input );
512 final OutputStreamWriter out = new OutputStreamWriter( output );
513 copy( in, out, bufferSize );
514 // NOTE: Unless anyone is planning on rewriting OutputStreamWriter, we have to flush
515 // here.
516 out.flush();
517 }
518
519 ///////////////////////////////////////////////////////////////
520 // String -> Writer
521
522 /**
523 * Copy chars from a <code>String</code> to a <code>Writer</code>.
524 * @param input Input string.
525 * @param output resulting output {@link Writer}
526 * @throws IOException in case of failure.
527 */
528 public static void copy( @Nonnull final String input, @Nonnull final Writer output )
529 throws IOException
530 {
531 output.write( input );
532 }
533
534 ///////////////////////////////////////////////////////////////
535 // String -> byte[]
536
537 /**
538 * Get the contents of a <code>String</code> as a <code>byte[]</code>.
539 * @param input The input size.
540 * @return The resulting byte array.
541 * @throws IOException in case of failure.
542 */
543 @Nonnull public static byte[] toByteArray( @Nonnull final String input )
544 throws IOException
545 {
546 return toByteArray( input, DEFAULT_BUFFER_SIZE );
547 }
548
549 /**
550 * Get the contents of a <code>String</code> as a <code>byte[]</code>.
551 *
552 * @param input The input size.
553 * @param bufferSize Size of internal buffer to use.
554 * @return The resulting byte array.
555 * @throws IOException in case of failure.
556 */
557 @Nonnull public static byte[] toByteArray( @Nonnull final String input, final int bufferSize )
558 throws IOException
559 {
560 ByteArrayOutputStream output = new ByteArrayOutputStream();
561 copy( input, output, bufferSize );
562 return output.toByteArray();
563 }
564
565 ///////////////////////////////////////////////////////////////
566 // Derived copy methods
567 // byte[] -> *
568 ///////////////////////////////////////////////////////////////
569
570 ///////////////////////////////////////////////////////////////
571 // byte[] -> Writer
572
573 /**
574 * Copy and convert bytes from a <code>byte[]</code> to chars on a
575 * <code>Writer</code>.
576 * The platform's default encoding is used for the byte-to-char conversion.
577 * @param input The input size.
578 * @param output The resulting output.
579 * @throws IOException in case of failure.
580 */
581 public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output )
582 throws IOException
583 {
584 copy( input, output, DEFAULT_BUFFER_SIZE );
585 }
586
587 /**
588 * Copy and convert bytes from a <code>byte[]</code> to chars on a
589 * <code>Writer</code>.
590 * The platform's default encoding is used for the byte-to-char conversion.
591 *
592 * @param input The input size.
593 * @param output The resulting output.
594 * @param bufferSize Size of internal buffer to use.
595 * @throws IOException in case of failure.
596 */
597 public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output, final int bufferSize )
598 throws IOException
599 {
600 final ByteArrayInputStream in = new ByteArrayInputStream( input );
601 copy( in, output, bufferSize );
602 }
603
604 /**
605 * Copy and convert bytes from a <code>byte[]</code> to chars on a
606 * <code>Writer</code>, using the specified encoding.
607 *
608 * @param encoding The name of a supported character encoding. See the
609 * <a href="http://www.iana.org/assignments/character-sets">IANA
610 * Charset Registry</a> for a list of valid encoding types.
611 * @param input The input size.
612 * @param output The resulting output.
613 * @throws IOException in case of failure.
614 */
615 public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output, final String encoding )
616 throws IOException
617 {
618 final ByteArrayInputStream in = new ByteArrayInputStream( input );
619 copy( in, output, encoding );
620 }
621
622 /**
623 * Copy and convert bytes from a <code>byte[]</code> to chars on a
624 * <code>Writer</code>, using the specified encoding.
625 *
626 * @param encoding The name of a supported character encoding. See the
627 * <a href="http://www.iana.org/assignments/character-sets">IANA
628 * Charset Registry</a> for a list of valid encoding types.
629 * @param input The input bytes.
630 * @param output The output buffer {@link Writer}
631 * @param bufferSize Size of internal buffer to use.
632 * @throws IOException in case of failure.
633 */
634 public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output, @Nonnull final String encoding,
635 final int bufferSize )
636 throws IOException
637 {
638 final ByteArrayInputStream in = new ByteArrayInputStream( input );
639 copy( in, output, encoding, bufferSize );
640 }
641
642 ///////////////////////////////////////////////////////////////
643 // byte[] -> String
644
645 /**
646 * Get the contents of a <code>byte[]</code> as a String.
647 * The platform's default encoding is used for the byte-to-char conversion.
648 * @param input The input bytes.
649 * @return The resulting string.
650 * @throws IOException in case of failure.
651 */
652 @Nonnull public static String toString( @Nonnull final byte[] input )
653 throws IOException
654 {
655 return toString( input, DEFAULT_BUFFER_SIZE );
656 }
657
658 /**
659 * Get the contents of a <code>byte[]</code> as a String.
660 * The platform's default encoding is used for the byte-to-char conversion.
661 *
662 * @param bufferSize Size of internal buffer to use.
663 * @param input The input bytes.
664 * @return The created string.
665 * @throws IOException in case of failure.
666 */
667 @Nonnull public static String toString( @Nonnull final byte[] input, final int bufferSize )
668 throws IOException
669 {
670 final StringWriter sw = new StringWriter();
671 copy( input, sw, bufferSize );
672 return sw.toString();
673 }
674
675 /**
676 * Get the contents of a <code>byte[]</code> as a String.
677 *
678 * @param encoding The name of a supported character encoding. See the
679 * <a href="http://www.iana.org/assignments/character-sets">IANA
680 * Charset Registry</a> for a list of valid encoding types.
681 * @param input The input bytes.
682 * @return The resulting string.
683 * @throws IOException in case of failure.
684 */
685 @Nonnull public static String toString( @Nonnull final byte[] input, @Nonnull final String encoding )
686 throws IOException
687 {
688 return toString( input, encoding, DEFAULT_BUFFER_SIZE );
689 }
690
691 /**
692 * Get the contents of a <code>byte[]</code> as a String.
693 *
694 * @param encoding The name of a supported character encoding. See the
695 * <a href="http://www.iana.org/assignments/character-sets">IANA
696 * Charset Registry</a> for a list of valid encoding types.
697 * @param bufferSize Size of internal buffer to use.
698 * @param input Input bytes.
699 * @return The resulting string.
700 * @throws IOException in case of failure.
701 */
702 @Nonnull public static String toString( @Nonnull final byte[] input, @Nonnull final String encoding,
703 final int bufferSize )
704 throws IOException
705 {
706 final StringWriter sw = new StringWriter();
707 copy( input, sw, encoding, bufferSize );
708 return sw.toString();
709 }
710
711 ///////////////////////////////////////////////////////////////
712 // byte[] -> OutputStream
713
714 /**
715 * Copy bytes from a <code>byte[]</code> to an <code>OutputStream</code>.
716 * @param input Input byte array.
717 * @param output output stream {@link OutputStream}
718 * @throws IOException in case of failure.
719 */
720 public static void copy( @Nonnull final byte[] input, @Nonnull final OutputStream output )
721 throws IOException
722 {
723 output.write( input );
724 }
725
726 /**
727 * Compare the contents of two Streams to determine if they are equal or not.
728 *
729 * @param input1 the first stream
730 * @param input2 the second stream
731 * @return true if the content of the streams are equal or they both don't exist, false otherwise
732 * @throws IOException in case of failure.
733 */
734 public static boolean contentEquals( @Nonnull final InputStream input1, @Nonnull final InputStream input2 )
735 throws IOException
736 {
737 final InputStream bufferedInput1 = new BufferedInputStream( input1 );
738 final InputStream bufferedInput2 = new BufferedInputStream( input2 );
739
740 int ch = bufferedInput1.read();
741 while ( -1 != ch )
742 {
743 final int ch2 = bufferedInput2.read();
744 if ( ch != ch2 )
745 {
746 return false;
747 }
748 ch = bufferedInput1.read();
749 }
750
751 final int ch2 = bufferedInput2.read();
752 return -1 == ch2;
753 }
754
755 // ----------------------------------------------------------------------
756 // closeXXX()
757 // ----------------------------------------------------------------------
758
759 /**
760 * Closes a {@code Channel} suppressing any {@code IOException}.
761 * <p>
762 * <b>Note:</b><br/>The usecase justifying this method is a shortcoming of the Java language up to but not including
763 * Java 7. For any code targetting Java 7 or later use of this method is highly discouraged and the
764 * {@code try-with-resources} statement should be used instead. Care must be taken to not use this method in a way
765 * {@code IOException}s get suppressed incorrectly.
766 * <strong>You must close all resources in use inside the {@code try} block to not suppress exceptions in the
767 * {@code finally} block incorrectly by using this method.</strong>
768 * </p>
769 * <p>
770 * <b>Example:</b><br/>
771 * <pre>
772 * // Introduce variables for the resources and initialize them to null. This cannot throw an exception.
773 * Closeable resource1 = null;
774 * Closeable resource2 = null;
775 * try
776 * {
777 * // Obtain a resource object and assign it to variable resource1. This may throw an exception.
778 * // If successful, resource1 != null.
779 * resource1 = ...
780 *
781 * // Obtain a resource object and assign it to variable resource2. This may throw an exception.
782 * // If successful, resource2 != null. Not reached if an exception has been thrown above.
783 * resource2 = ...
784 *
785 * // Perform operations on the resources. This may throw an exception. Not reached if an exception has been
786 * // thrown above. Note: Treat the variables resource1 and resource2 the same way as if they would have been
787 * // declared with the final modifier - that is - do NOT write anyting like resource1 = something else or
788 * // resource2 = something else here.
789 * resource1 ...
790 * resource2 ...
791 *
792 * // Finally, close the resources and set the variables to null indicating successful completion.
793 * // This may throw an exception. Not reached if an exception has been thrown above.
794 * resource1.close();
795 * resource1 = null;
796 * // Not reached if an exception has been thrown above.
797 * resource2.close();
798 * resource2 = null;
799 *
800 * // All resources are closed at this point and all operations (up to here) completed successfully without
801 * // throwing an exception we would need to handle (by letting it propagate or by catching and handling it).
802 * }
803 * finally
804 * {
805 * // Cleanup any resource not closed in the try block due to an exception having been thrown and suppress any
806 * // exception this may produce to not stop the exception from the try block to be propagated. If the try
807 * // block completed successfully, all variables will have been set to null there and this will not do
808 * // anything. This is just to cleanup properly in case of an exception.
809 *
810 * IOUtil.close( resource1 );
811 * IOUtil.close( resource2 );
812 *
813 * // Without that utility method you would need to write the following:
814 * //
815 * // try
816 * // {
817 * // if ( resource1 != null )
818 * // {
819 * // resource1.close();
820 * // }
821 * // }
822 * // catch( IOException e )
823 * // {
824 * // Suppressed. If resource1 != null, an exception has already been thrown in the try block we need to
825 * // propagate instead of this one.
826 * // }
827 * // finally
828 * // {
829 * // try
830 * // {
831 * // if ( resource2 != null )
832 * // {
833 * // resource2.close();
834 * // }
835 * // }
836 * // catch ( IOException e )
837 * // {
838 * // Suppressed. If resource2 != null, an exception has already been thrown in the try block we need to
839 * // propagate instead of this one.
840 * // }
841 * // }
842 * }
843 * </pre>
844 * </p>
845 *
846 * @param channel The channel to close or {@code null}.
847 */
848 public static void close( @Nullable Channel channel )
849 {
850 try
851 {
852 if ( channel != null )
853 {
854 channel.close();
855 }
856 }
857 catch ( IOException ex )
858 {
859 // Suppressed
860 }
861 }
862
863 /**
864 * Closes an {@code InputStream} suppressing any {@code IOException}.
865 * <p>
866 * <b>Note:</b><br/>The usecase justifying this method is a shortcoming of the Java language up to but not including
867 * Java 7. For any code targeting Java 7 or later use of this method is highly discouraged and the
868 * {@code try-with-resources} statement should be used instead. Care must be taken to not use this method in a way
869 * {@code IOException}s get suppressed incorrectly.
870 * <strong>You must close all resources in use inside the {@code try} block to not suppress exceptions in the
871 * {@code finally} block incorrectly by using this method.</strong>
872 * </p>
873 * <p>
874 * <b>Example:</b><br/>
875 * <pre>
876 * // Introduce variables for the resources and initialize them to null. This cannot throw an exception.
877 * Closeable resource1 = null;
878 * Closeable resource2 = null;
879 * try
880 * {
881 * // Obtain a resource object and assign it to variable resource1. This may throw an exception.
882 * // If successful, resource1 != null.
883 * resource1 = ...
884 *
885 * // Obtain a resource object and assign it to variable resource2. This may throw an exception.
886 * // If successful, resource2 != null. Not reached if an exception has been thrown above.
887 * resource2 = ...
888 *
889 * // Perform operations on the resources. This may throw an exception. Not reached if an exception has been
890 * // thrown above. Note: Treat the variables resource1 and resource2 the same way as if they would have been
891 * // declared with the final modifier - that is - do NOT write anyting like resource1 = something else or
892 * // resource2 = something else here.
893 * resource1 ...
894 * resource2 ...
895 *
896 * // Finally, close the resources and set the variables to null indicating successful completion.
897 * // This may throw an exception. Not reached if an exception has been thrown above.
898 * resource1.close();
899 * resource1 = null;
900 * // This may throw an exception. Not reached if an exception has been thrown above.
901 * resource2.close();
902 * resource2 = null;
903 *
904 * // All resources are closed at this point and all operations (up to here) completed successfully without
905 * // throwing an exception we would need to handle (by letting it propagate or by catching and handling it).
906 * }
907 * finally
908 * {
909 * // Cleanup any resource not closed in the try block due to an exception having been thrown and suppress any
910 * // exception this may produce to not stop the exception from the try block to be propagated. If the try
911 * // block completed successfully, all variables will have been set to null there and this will not do
912 * // anything. This is just to cleanup properly in case of an exception.
913 *
914 * IOUtil.close( resource1 );
915 * IOUtil.close( resource2 );
916 *
917 * // Without that utility method you would need to write the following:
918 * //
919 * // try
920 * // {
921 * // if ( resource1 != null )
922 * // {
923 * // resource1.close();
924 * // }
925 * // }
926 * // catch( IOException e )
927 * // {
928 * // Suppressed. If resource1 != null, an exception has already been thrown in the try block we need to
929 * // propagate instead of this one.
930 * // }
931 * // finally
932 * // {
933 * // try
934 * // {
935 * // if ( resource2 != null )
936 * // {
937 * // resource2.close();
938 * // }
939 * // }
940 * // catch ( IOException e )
941 * // {
942 * // Suppressed. If resource2 != null, an exception has already been thrown in the try block we need to
943 * // propagate instead of this one.
944 * // }
945 * // }
946 * }
947 * </pre>
948 * </p>
949 *
950 * @param inputStream The stream to close or {@code null}.
951 */
952 public static void close( @Nullable InputStream inputStream )
953 {
954 try
955 {
956 if ( inputStream != null )
957 {
958 inputStream.close();
959 }
960 }
961 catch ( IOException ex )
962 {
963 // Suppressed
964 }
965 }
966
967 /**
968 * Closes an {@code OutputStream} suppressing any {@code IOException}.
969 * <p>
970 * <b>Note:</b><br/>The usecase justifying this method is a shortcoming of the Java language up to but not including
971 * Java 7. For any code targeting Java 7 or later use of this method is highly discouraged and the
972 * {@code try-with-resources} statement should be used instead. Care must be taken to not use this method in a way
973 * {@code IOException}s get suppressed incorrectly.
974 * <strong>You must close all resources in use inside the {@code try} block to not suppress exceptions in the
975 * {@code finally} block incorrectly by using this method.</strong>
976 * </p>
977 * <p>
978 * <b>Example:</b><br/>
979 * <pre>
980 * // Introduce variables for the resources and initialize them to null. This cannot throw an exception.
981 * Closeable resource1 = null;
982 * Closeable resource2 = null;
983 * try
984 * {
985 * // Obtain a resource object and assign it to variable resource1. This may throw an exception.
986 * // If successful, resource1 != null.
987 * resource1 = ...
988 *
989 * // Obtain a resource object and assign it to variable resource2. This may throw an exception.
990 * // If successful, resource2 != null. Not reached if an exception has been thrown above.
991 * resource2 = ...
992 *
993 * // Perform operations on the resources. This may throw an exception. Not reached if an exception has been
994 * // thrown above. Note: Treat the variables resource1 and resource2 the same way as if they would have been
995 * // declared with the final modifier - that is - do NOT write anyting like resource1 = something else or
996 * // resource2 = something else here.
997 * resource1 ...
998 * resource2 ...
999 *
1000 * // Finally, close the resources and set the variables to null indicating successful completion.
1001 * // This may throw an exception. Not reached if an exception has been thrown above.
1002 * resource1.close();
1003 * resource1 = null;
1004 * // This may throw an exception. Not reached if an exception has been thrown above.
1005 * resource2.close();
1006 * resource2 = null;
1007 *
1008 * // All resources are closed at this point and all operations (up to here) completed successfully without
1009 * // throwing an exception we would need to handle (by letting it propagate or by catching and handling it).
1010 * }
1011 * finally
1012 * {
1013 * // Cleanup any resource not closed in the try block due to an exception having been thrown and suppress any
1014 * // exception this may produce to not stop the exception from the try block to be propagated. If the try
1015 * // block completed successfully, all variables will have been set to null there and this will not do
1016 * // anything. This is just to cleanup properly in case of an exception.
1017 *
1018 * IOUtil.close( resource1 );
1019 * IOUtil.close( resource2 );
1020 *
1021 * // Without that utility method you would need to write the following:
1022 * //
1023 * // try
1024 * // {
1025 * // if ( resource1 != null )
1026 * // {
1027 * // resource1.close();
1028 * // }
1029 * // }
1030 * // catch( IOException e )
1031 * // {
1032 * // Suppressed. If resource1 != null, an exception has already been thrown in the try block we need to
1033 * // propagate instead of this one.
1034 * // }
1035 * // finally
1036 * // {
1037 * // try
1038 * // {
1039 * // if ( resource2 != null )
1040 * // {
1041 * // resource2.close();
1042 * // }
1043 * // }
1044 * // catch ( IOException e )
1045 * // {
1046 * // Suppressed. If resource2 != null, an exception has already been thrown in the try block we need to
1047 * // propagate instead of this one.
1048 * // }
1049 * // }
1050 * }
1051 * </pre>
1052 * </p>
1053 *
1054 * @param outputStream The stream to close or {@code null}.
1055 */
1056 public static void close( @Nullable OutputStream outputStream )
1057 {
1058 try
1059 {
1060 if ( outputStream != null )
1061 {
1062 outputStream.close();
1063 }
1064 }
1065 catch ( IOException ex )
1066 {
1067 // Suppressed
1068 }
1069 }
1070
1071 /**
1072 * Closes a {@code Reader} suppressing any {@code IOException}.
1073 * <p>
1074 * <b>Note:</b><br/>The usecase justifying this method is a shortcoming of the Java language up to but not including
1075 * Java 7. For any code targeting Java 7 or later use of this method is highly discouraged and the
1076 * {@code try-with-resources} statement should be used instead. Care must be taken to not use this method in a way
1077 * {@code IOException}s get suppressed incorrectly.
1078 * <strong>You must close all resources in use inside the {@code try} block to not suppress exceptions in the
1079 * {@code finally} block incorrectly by using this method.</strong>
1080 * </p>
1081 * <p>
1082 * <b>Example:</b><br/>
1083 * <pre>
1084 * // Introduce variables for the resources and initialize them to null. This cannot throw an exception.
1085 * Closeable resource1 = null;
1086 * Closeable resource2 = null;
1087 * try
1088 * {
1089 * // Obtain a resource object and assign it to variable resource1. This may throw an exception.
1090 * // If successful, resource1 != null.
1091 * resource1 = ...
1092 *
1093 * // Obtain a resource object and assign it to variable resource2. This may throw an exception.
1094 * // If successful, resource2 != null. Not reached if an exception has been thrown above.
1095 * resource2 = ...
1096 *
1097 * // Perform operations on the resources. This may throw an exception. Not reached if an exception has been
1098 * // thrown above. Note: Treat the variables resource1 and resource2 the same way as if they would have been
1099 * // declared with the final modifier - that is - do NOT write anyting like resource1 = something else or
1100 * // resource2 = something else here.
1101 * resource1 ...
1102 * resource2 ...
1103 *
1104 * // Finally, close the resources and set the variables to null indicating successful completion.
1105 * // This may throw an exception. Not reached if an exception has been thrown above.
1106 * resource1.close();
1107 * resource1 = null;
1108 * // This may throw an exception. Not reached if an exception has been thrown above.
1109 * resource2.close();
1110 * resource2 = null;
1111 *
1112 * // All resources are closed at this point and all operations (up to here) completed successfully without
1113 * // throwing an exception we would need to handle (by letting it propagate or by catching and handling it).
1114 * }
1115 * finally
1116 * {
1117 * // Cleanup any resource not closed in the try block due to an exception having been thrown and suppress any
1118 * // exception this may produce to not stop the exception from the try block to be propagated. If the try
1119 * // block completed successfully, all variables will have been set to null there and this will not do
1120 * // anything. This is just to cleanup properly in case of an exception.
1121 *
1122 * IOUtil.close( resource1 );
1123 * IOUtil.close( resource2 );
1124 *
1125 * // Without that utility method you would need to write the following:
1126 * //
1127 * // try
1128 * // {
1129 * // if ( resource1 != null )
1130 * // {
1131 * // resource1.close();
1132 * // }
1133 * // }
1134 * // catch( IOException e )
1135 * // {
1136 * // Suppressed. If resource1 != null, an exception has already been thrown in the try block we need to
1137 * // propagate instead of this one.
1138 * // }
1139 * // finally
1140 * // {
1141 * // try
1142 * // {
1143 * // if ( resource2 != null )
1144 * // {
1145 * // resource2.close();
1146 * // }
1147 * // }
1148 * // catch ( IOException e )
1149 * // {
1150 * // Suppressed. If resource2 != null, an exception has already been thrown in the try block we need to
1151 * // propagate instead of this one.
1152 * // }
1153 * // }
1154 * }
1155 * </pre>
1156 * </p>
1157 *
1158 * @param reader The reader to close or {@code null}.
1159 */
1160 public static void close( @Nullable Reader reader )
1161 {
1162 try
1163 {
1164 if ( reader != null )
1165 {
1166 reader.close();
1167 }
1168 }
1169 catch ( IOException ex )
1170 {
1171 // Suppressed
1172 }
1173 }
1174
1175 /**
1176 * Closes a {@code Writer} suppressing any {@code IOException}.
1177 * <p>
1178 * <b>Note:</b><br/>The usecase justifying this method is a shortcoming of the Java language up to but not including
1179 * Java 7. For any code targeting Java 7 or later use of this method is highly discouraged and the
1180 * {@code try-with-resources} statement should be used instead. Care must be taken to not use this method in a way
1181 * {@code IOException}s get suppressed incorrectly.
1182 * <strong>You must close all resources in use inside the {@code try} block to not suppress exceptions in the
1183 * {@code finally} block incorrectly by using this method.</strong>
1184 * </p>
1185 * <p>
1186 * <b>Example:</b><br/>
1187 * <pre>
1188 * // Introduce variables for the resources and initialize them to null. This cannot throw an exception.
1189 * Closeable resource1 = null;
1190 * Closeable resource2 = null;
1191 * try
1192 * {
1193 * // Obtain a resource object and assign it to variable resource1. This may throw an exception.
1194 * // If successful, resource1 != null.
1195 * resource1 = ...
1196 *
1197 * // Obtain a resource object and assign it to variable resource2. This may throw an exception.
1198 * // If successful, resource2 != null. Not reached if an exception has been thrown above.
1199 * resource2 = ...
1200 *
1201 * // Perform operations on the resources. This may throw an exception. Not reached if an exception has been
1202 * // thrown above. Note: Treat the variables resource1 and resource2 the same way as if they would have been
1203 * // declared with the final modifier - that is - do NOT write anyting like resource1 = something else or
1204 * // resource2 = something else here.
1205 * resource1 ...
1206 * resource2 ...
1207 *
1208 * // Finally, close the resources and set the variables to null indicating successful completion.
1209 * // This may throw an exception. Not reached if an exception has been thrown above.
1210 * resource1.close();
1211 * resource1 = null;
1212 * // This may throw an exception. Not reached if an exception has been thrown above.
1213 * resource2.close();
1214 * resource2 = null;
1215 *
1216 * // All resources are closed at this point and all operations (up to here) completed successfully without
1217 * // throwing an exception we would need to handle (by letting it propagate or by catching and handling it).
1218 * }
1219 * finally
1220 * {
1221 * // Cleanup any resource not closed in the try block due to an exception having been thrown and suppress any
1222 * // exception this may produce to not stop the exception from the try block to be propagated. If the try
1223 * // block completed successfully, all variables will have been set to null there and this will not do
1224 * // anything. This is just to cleanup properly in case of an exception.
1225 *
1226 * IOUtil.close( resource1 );
1227 * IOUtil.close( resource2 );
1228 *
1229 * // Without that utility method you would need to write the following:
1230 * //
1231 * // try
1232 * // {
1233 * // if ( resource1 != null )
1234 * // {
1235 * // resource1.close();
1236 * // }
1237 * // }
1238 * // catch( IOException e )
1239 * // {
1240 * // Suppressed. If resource1 != null, an exception has already been thrown in the try block we need to
1241 * // propagate instead of this one.
1242 * // }
1243 * // finally
1244 * // {
1245 * // try
1246 * // {
1247 * // if ( resource2 != null )
1248 * // {
1249 * // resource2.close();
1250 * // }
1251 * // }
1252 * // catch ( IOException e )
1253 * // {
1254 * // Suppressed. If resource2 != null, an exception has already been thrown in the try block we need to
1255 * // propagate instead of this one.
1256 * // }
1257 * // }
1258 * }
1259 * </pre>
1260 * </p>
1261 *
1262 * @param writer The writer to close or {@code null}.
1263 */
1264 public static void close( @Nullable Writer writer )
1265 {
1266 try
1267 {
1268 if ( writer != null )
1269 {
1270 writer.close();
1271 }
1272 }
1273 catch ( IOException ex )
1274 {
1275 // Suppressed
1276 }
1277 }
1278 }