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33895a7b NR |
1 | package be.nikiroo.utils; |
2 | ||
3 | import java.io.IOException; | |
4 | import java.io.InputStream; | |
5 | import java.util.Arrays; | |
6 | ||
7 | /** | |
8 | * A simple {@link InputStream} that is buffered with a bytes array. | |
9 | * <p> | |
10 | * It is mostly intended to be used as a base class to create new | |
11 | * {@link InputStream}s with special operation modes, and to give some default | |
12 | * methods. | |
13 | * | |
14 | * @author niki | |
15 | */ | |
16 | public class BufferedInputStream extends InputStream { | |
17 | protected int pos; | |
18 | protected int len; | |
19 | protected byte[] buffer; | |
20 | protected boolean eof; | |
21 | ||
22 | private boolean closed; | |
23 | private InputStream in; | |
24 | private int openCounter; | |
25 | ||
26 | // special use, prefetched next buffer | |
27 | private byte[] buffer2; | |
28 | private int pos2; | |
29 | private int len2; | |
30 | private byte[] originalBuffer; | |
31 | ||
32 | private long bytesRead; | |
33 | ||
34 | /** | |
35 | * Create a new {@link BufferedInputStream} that wraps the given | |
36 | * {@link InputStream}. | |
37 | * | |
38 | * @param in | |
39 | * the {@link InputStream} to wrap | |
40 | */ | |
41 | public BufferedInputStream(InputStream in) { | |
42 | this.in = in; | |
43 | ||
44 | this.buffer = new byte[4096]; | |
45 | this.originalBuffer = this.buffer; | |
46 | this.pos = 0; | |
47 | this.len = 0; | |
48 | } | |
49 | ||
50 | /** | |
51 | * Create a new {@link BufferedInputStream} that wraps the given bytes array | |
52 | * as a data source. | |
53 | * | |
54 | * @param in | |
55 | * the array to wrap, cannot be NULL | |
56 | */ | |
57 | public BufferedInputStream(byte[] in) { | |
58 | this(in, 0, in.length); | |
59 | } | |
60 | ||
61 | /** | |
62 | * Create a new {@link BufferedInputStream} that wraps the given bytes array | |
63 | * as a data source. | |
64 | * | |
65 | * @param in | |
66 | * the array to wrap, cannot be NULL | |
67 | * @param offset | |
68 | * the offset to start the reading at | |
69 | * @param length | |
70 | * the number of bytes to take into account in the array, | |
71 | * starting from the offset | |
72 | * | |
73 | * @throws NullPointerException | |
74 | * if the array is NULL | |
75 | * @throws IndexOutOfBoundsException | |
76 | * if the offset and length do not correspond to the given array | |
77 | */ | |
78 | public BufferedInputStream(byte[] in, int offset, int length) { | |
79 | if (in == null) { | |
80 | throw new NullPointerException(); | |
81 | } else if (offset < 0 || length < 0 || length > in.length - offset) { | |
82 | throw new IndexOutOfBoundsException(); | |
83 | } | |
84 | ||
85 | this.in = null; | |
86 | ||
87 | this.buffer = in; | |
88 | this.originalBuffer = this.buffer; | |
89 | this.pos = offset; | |
90 | this.len = length; | |
91 | } | |
92 | ||
93 | /** | |
94 | * Return this very same {@link BufferedInputStream}, but keep a counter of | |
95 | * how many streams were open this way. When calling | |
96 | * {@link BufferedInputStream#close()}, decrease this counter if it is not | |
97 | * already zero instead of actually closing the stream. | |
98 | * <p> | |
99 | * You are now responsible for it — you <b>must</b> close it. | |
100 | * <p> | |
101 | * This method allows you to use a wrapping stream around this one and still | |
102 | * close the wrapping stream. | |
103 | * | |
104 | * @return the same stream, but you are now responsible for closing it | |
105 | * | |
106 | * @throws IOException | |
107 | * in case of I/O error or if the stream is closed | |
108 | */ | |
109 | public synchronized InputStream open() throws IOException { | |
110 | checkClose(); | |
111 | openCounter++; | |
112 | return this; | |
113 | } | |
114 | ||
115 | // max is buffer.size ! | |
116 | public boolean startsWiths(String search) throws IOException { | |
117 | return startsWith(search.getBytes("UTF-8")); | |
118 | } | |
119 | ||
120 | // max is buffer.size ! | |
121 | public boolean startsWith(byte[] search) throws IOException { | |
122 | if (search.length > originalBuffer.length) { | |
123 | throw new IOException( | |
124 | "This stream does not support searching for more than " | |
125 | + buffer.length + " bytes"); | |
126 | } | |
127 | ||
128 | checkClose(); | |
129 | ||
130 | if (available() < search.length) { | |
131 | preRead(); | |
132 | } | |
133 | ||
134 | if (available() >= search.length) { | |
135 | // Easy path | |
136 | return startsWith(search, buffer, pos); | |
137 | } else if (!eof) { | |
138 | // Harder path | |
139 | if (buffer2 == null && buffer.length == originalBuffer.length) { | |
140 | buffer2 = Arrays.copyOf(buffer, buffer.length * 2); | |
141 | ||
142 | pos2 = buffer.length; | |
143 | len2 = in.read(buffer2, pos2, buffer.length); | |
144 | if (len2 > 0) { | |
145 | bytesRead += len2; | |
146 | } | |
147 | ||
148 | // Note: here, len/len2 = INDEX of last good byte | |
149 | len2 += pos2; | |
150 | } | |
151 | ||
152 | if (available() + (len2 - pos2) >= search.length) { | |
153 | return startsWith(search, buffer2, pos2); | |
154 | } | |
155 | } | |
156 | ||
157 | return false; | |
158 | } | |
159 | ||
160 | /** | |
161 | * The number of bytes read from the under-laying {@link InputStream}. | |
162 | * | |
163 | * @return the number of bytes | |
164 | */ | |
165 | public long getBytesRead() { | |
166 | return bytesRead; | |
167 | } | |
168 | ||
169 | /** | |
170 | * Check if this stream is totally spent (no more data to read or to | |
171 | * process). | |
172 | * <p> | |
173 | * Note: an empty stream that is still not started will return FALSE, as we | |
174 | * don't know yet if it is empty. | |
175 | * | |
176 | * @return TRUE if it is | |
177 | */ | |
178 | public boolean eof() { | |
179 | return closed || (len < 0 && !hasMoreData()); | |
180 | } | |
181 | ||
182 | @Override | |
183 | public int read() throws IOException { | |
184 | checkClose(); | |
185 | ||
186 | preRead(); | |
187 | if (eof) { | |
188 | return -1; | |
189 | } | |
190 | ||
191 | return buffer[pos++]; | |
192 | } | |
193 | ||
194 | @Override | |
195 | public int read(byte[] b) throws IOException { | |
196 | return read(b, 0, b.length); | |
197 | } | |
198 | ||
199 | @Override | |
200 | public int read(byte[] b, int boff, int blen) throws IOException { | |
201 | checkClose(); | |
202 | ||
203 | if (b == null) { | |
204 | throw new NullPointerException(); | |
205 | } else if (boff < 0 || blen < 0 || blen > b.length - boff) { | |
206 | throw new IndexOutOfBoundsException(); | |
207 | } else if (blen == 0) { | |
208 | return 0; | |
209 | } | |
210 | ||
211 | int done = 0; | |
212 | while (hasMoreData() && done < blen) { | |
213 | preRead(); | |
214 | if (hasMoreData()) { | |
215 | int now = Math.min(blen, len) - pos; | |
216 | if (now > 0) { | |
217 | System.arraycopy(buffer, pos, b, boff, now); | |
218 | pos += now; | |
219 | done += now; | |
220 | } | |
221 | } | |
222 | } | |
223 | ||
224 | return done > 0 ? done : -1; | |
225 | } | |
226 | ||
227 | @Override | |
228 | public long skip(long n) throws IOException { | |
229 | if (n <= 0) { | |
230 | return 0; | |
231 | } | |
232 | ||
233 | long skipped = 0; | |
234 | while (hasMoreData() && n > 0) { | |
235 | preRead(); | |
236 | ||
237 | long inBuffer = Math.min(n, available()); | |
238 | pos += inBuffer; | |
239 | n -= inBuffer; | |
240 | skipped += inBuffer; | |
241 | } | |
242 | ||
243 | return skipped; | |
244 | } | |
245 | ||
246 | @Override | |
247 | public int available() { | |
248 | if (closed) { | |
249 | return 0; | |
250 | } | |
251 | ||
252 | return Math.max(0, len - pos); | |
253 | } | |
254 | ||
255 | /** | |
256 | * Closes this stream and releases any system resources associated with the | |
257 | * stream. | |
258 | * <p> | |
259 | * Including the under-laying {@link InputStream}. | |
260 | * <p> | |
261 | * <b>Note:</b> if you called the {@link BufferedInputStream#open()} method | |
262 | * prior to this one, it will just decrease the internal count of how many | |
263 | * open streams it held and do nothing else. The stream will actually be | |
264 | * closed when you have called {@link BufferedInputStream#close()} once more | |
265 | * than {@link BufferedInputStream#open()}. | |
266 | * | |
267 | * @exception IOException | |
268 | * in case of I/O error | |
269 | */ | |
270 | @Override | |
271 | public synchronized void close() throws IOException { | |
272 | close(true); | |
273 | } | |
274 | ||
275 | /** | |
276 | * Closes this stream and releases any system resources associated with the | |
277 | * stream. | |
278 | * <p> | |
279 | * Including the under-laying {@link InputStream} if | |
280 | * <tt>incudingSubStream</tt> is true. | |
281 | * <p> | |
282 | * You can call this method multiple times, it will not cause an | |
283 | * {@link IOException} for subsequent calls. | |
284 | * <p> | |
285 | * <b>Note:</b> if you called the {@link BufferedInputStream#open()} method | |
286 | * prior to this one, it will just decrease the internal count of how many | |
287 | * open streams it held and do nothing else. The stream will actually be | |
288 | * closed when you have called {@link BufferedInputStream#close()} once more | |
289 | * than {@link BufferedInputStream#open()}. | |
290 | * | |
291 | * @exception IOException | |
292 | * in case of I/O error | |
293 | */ | |
294 | public synchronized void close(boolean includingSubStream) | |
295 | throws IOException { | |
296 | if (!closed) { | |
297 | if (openCounter > 0) { | |
298 | openCounter--; | |
299 | } else { | |
300 | closed = true; | |
301 | if (includingSubStream && in != null) { | |
302 | in.close(); | |
303 | } | |
304 | } | |
305 | } | |
306 | } | |
307 | ||
308 | /** | |
309 | * Check if we still have some data in the buffer and, if not, fetch some. | |
310 | * | |
311 | * @return TRUE if we fetched some data, FALSE if there are still some in | |
312 | * the buffer | |
313 | * | |
314 | * @throws IOException | |
315 | * in case of I/O error | |
316 | */ | |
317 | protected boolean preRead() throws IOException { | |
318 | boolean hasRead = false; | |
319 | if (!eof && in != null && pos >= len) { | |
320 | pos = 0; | |
321 | if (buffer2 != null) { | |
322 | buffer = buffer2; | |
323 | pos = pos2; | |
324 | len = len2; | |
325 | ||
326 | buffer2 = null; | |
327 | pos2 = 0; | |
328 | len2 = 0; | |
329 | } else { | |
330 | buffer = originalBuffer; | |
331 | ||
332 | len = read(in, buffer); | |
333 | if (len > 0) { | |
334 | bytesRead += len; | |
335 | } | |
336 | } | |
337 | ||
338 | hasRead = true; | |
339 | } | |
340 | ||
341 | if (pos >= len) { | |
342 | eof = true; | |
343 | } | |
344 | ||
345 | return hasRead; | |
346 | } | |
347 | ||
348 | /** | |
349 | * Read the under-laying stream into the local buffer. | |
350 | * | |
351 | * @param in | |
352 | * the under-laying {@link InputStream} | |
353 | * @param buffer | |
354 | * the buffer we use in this {@link BufferedInputStream} | |
355 | * | |
356 | * @return the number of bytes read | |
357 | * | |
358 | * @throws IOException | |
359 | * in case of I/O error | |
360 | */ | |
361 | protected int read(InputStream in, byte[] buffer) throws IOException { | |
362 | return in.read(buffer); | |
363 | } | |
364 | ||
365 | /** | |
366 | * We have more data available in the buffer or we can fetch more. | |
367 | * | |
368 | * @return TRUE if it is the case, FALSE if not | |
369 | */ | |
370 | protected boolean hasMoreData() { | |
371 | return !closed && !(eof && pos >= len); | |
372 | } | |
373 | ||
374 | /** | |
375 | * Check that the stream was not closed, and throw an {@link IOException} if | |
376 | * it was. | |
377 | * | |
378 | * @throws IOException | |
379 | * if it was closed | |
380 | */ | |
381 | protected void checkClose() throws IOException { | |
382 | if (closed) { | |
383 | throw new IOException( | |
384 | "This NextableInputStream was closed, you cannot use it anymore."); | |
385 | } | |
386 | } | |
387 | ||
388 | // buffer must be > search | |
389 | static private boolean startsWith(byte[] search, byte[] buffer, int offset) { | |
390 | boolean same = true; | |
391 | for (int i = 0; i < search.length; i++) { | |
392 | if (search[i] != buffer[offset + i]) { | |
393 | same = false; | |
394 | break; | |
395 | } | |
396 | } | |
397 | ||
398 | return same; | |
399 | } | |
400 | } |