J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1999-2007 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.imageio.stream; |
| 27 | |
| 28 | import java.io.DataInput; |
| 29 | import java.io.IOException; |
| 30 | import java.nio.ByteOrder; |
| 31 | |
| 32 | /** |
| 33 | * A seekable input stream interface for use by |
| 34 | * <code>ImageReader</code>s. Various input sources, such as |
| 35 | * <code>InputStream</code>s and <code>File</code>s, |
| 36 | * as well as future fast I/O sources may be "wrapped" by a suitable |
| 37 | * implementation of this interface for use by the Image I/O API. |
| 38 | * |
| 39 | * @see ImageInputStreamImpl |
| 40 | * @see FileImageInputStream |
| 41 | * @see FileCacheImageInputStream |
| 42 | * @see MemoryCacheImageInputStream |
| 43 | * |
| 44 | */ |
| 45 | public interface ImageInputStream extends DataInput { |
| 46 | |
| 47 | /** |
| 48 | * Sets the desired byte order for future reads of data values |
| 49 | * from this stream. For example, the sequence of bytes '0x01 |
| 50 | * 0x02 0x03 0x04' if read as a 4-byte integer would have the |
| 51 | * value '0x01020304' using network byte order and the value |
| 52 | * '0x04030201' under the reverse byte order. |
| 53 | * |
| 54 | * <p> The enumeration class <code>java.nio.ByteOrder</code> is |
| 55 | * used to specify the byte order. A value of |
| 56 | * <code>ByteOrder.BIG_ENDIAN</code> specifies so-called |
| 57 | * big-endian or network byte order, in which the high-order byte |
| 58 | * comes first. Motorola and Sparc processors store data in this |
| 59 | * format, while Intel processors store data in the reverse |
| 60 | * <code>ByteOrder.LITTLE_ENDIAN</code> order. |
| 61 | * |
| 62 | * <p> The byte order has no effect on the results returned from |
| 63 | * the <code>readBits</code> method (or the value written by |
| 64 | * <code>ImageOutputStream.writeBits</code>). |
| 65 | * |
| 66 | * @param byteOrder one of <code>ByteOrder.BIG_ENDIAN</code> or |
| 67 | * <code>java.nio.ByteOrder.LITTLE_ENDIAN</code>, indicating whether |
| 68 | * network byte order or its reverse will be used for future |
| 69 | * reads. |
| 70 | * |
| 71 | * @see java.nio.ByteOrder |
| 72 | * @see #getByteOrder |
| 73 | * @see #readBits(int) |
| 74 | */ |
| 75 | void setByteOrder(ByteOrder byteOrder); |
| 76 | |
| 77 | /** |
| 78 | * Returns the byte order with which data values will be read from |
| 79 | * this stream as an instance of the |
| 80 | * <code>java.nio.ByteOrder</code> enumeration. |
| 81 | * |
| 82 | * @return one of <code>ByteOrder.BIG_ENDIAN</code> or |
| 83 | * <code>ByteOrder.LITTLE_ENDIAN</code>, indicating which byte |
| 84 | * order is being used. |
| 85 | * |
| 86 | * @see java.nio.ByteOrder |
| 87 | * @see #setByteOrder |
| 88 | */ |
| 89 | ByteOrder getByteOrder(); |
| 90 | |
| 91 | /** |
| 92 | * Reads a single byte from the stream and returns it as an |
| 93 | * integer between 0 and 255. If the end of the stream is |
| 94 | * reached, -1 is returned. |
| 95 | * |
| 96 | * <p> The bit offset within the stream is reset to zero before |
| 97 | * the read occurs. |
| 98 | * |
| 99 | * @return a byte value from the stream, as an int, or -1 to |
| 100 | * indicate EOF. |
| 101 | * |
| 102 | * @exception IOException if an I/O error occurs. |
| 103 | */ |
| 104 | int read() throws IOException; |
| 105 | |
| 106 | /** |
| 107 | * Reads up to <code>b.length</code> bytes from the stream, and |
| 108 | * stores them into <code>b</code> starting at index 0. The |
| 109 | * number of bytes read is returned. If no bytes can be read |
| 110 | * because the end of the stream has been reached, -1 is returned. |
| 111 | * |
| 112 | * <p> The bit offset within the stream is reset to zero before |
| 113 | * the read occurs. |
| 114 | * |
| 115 | * @param b an array of bytes to be written to. |
| 116 | * |
| 117 | * @return the number of bytes actually read, or <code>-1</code> |
| 118 | * to indicate EOF. |
| 119 | * |
| 120 | * @exception NullPointerException if <code>b</code> is |
| 121 | * <code>null</code>. |
| 122 | * |
| 123 | * @exception IOException if an I/O error occurs. |
| 124 | */ |
| 125 | int read(byte[] b) throws IOException; |
| 126 | |
| 127 | /** |
| 128 | * Reads up to <code>len</code> bytes from the stream, and stores |
| 129 | * them into <code>b</code> starting at index <code>off</code>. |
| 130 | * The number of bytes read is returned. If no bytes can be read |
| 131 | * because the end of the stream has been reached, <code>-1</code> |
| 132 | * is returned. |
| 133 | * |
| 134 | * <p> The bit offset within the stream is reset to zero before |
| 135 | * the read occurs. |
| 136 | * |
| 137 | * @param b an array of bytes to be written to. |
| 138 | * @param off the starting position within <code>b</code> to write to. |
| 139 | * @param len the maximum number of <code>byte</code>s to read. |
| 140 | * |
| 141 | * @return the number of bytes actually read, or <code>-1</code> |
| 142 | * to indicate EOF. |
| 143 | * |
| 144 | * @exception NullPointerException if <code>b</code> is |
| 145 | * <code>null</code>. |
| 146 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 147 | * negative, <code>len</code> is negative, or <code>off + |
| 148 | * len</code> is greater than <code>b.length</code>. |
| 149 | * @exception IOException if an I/O error occurs. |
| 150 | */ |
| 151 | int read(byte[] b, int off, int len) throws IOException; |
| 152 | |
| 153 | /** |
| 154 | * Reads up to <code>len</code> bytes from the stream, and |
| 155 | * modifies the supplied <code>IIOByteBuffer</code> to indicate |
| 156 | * the byte array, offset, and length where the data may be found. |
| 157 | * The caller should not attempt to modify the data found in the |
| 158 | * <code>IIOByteBuffer</code>. |
| 159 | * |
| 160 | * <p> The bit offset within the stream is reset to zero before |
| 161 | * the read occurs. |
| 162 | * |
| 163 | * @param buf an IIOByteBuffer object to be modified. |
| 164 | * @param len the maximum number of <code>byte</code>s to read. |
| 165 | * |
| 166 | * @exception IndexOutOfBoundsException if <code>len</code> is |
| 167 | * negative. |
| 168 | * @exception NullPointerException if <code>buf</code> is |
| 169 | * <code>null</code>. |
| 170 | * |
| 171 | * @exception IOException if an I/O error occurs. |
| 172 | */ |
| 173 | void readBytes(IIOByteBuffer buf, int len) throws IOException; |
| 174 | |
| 175 | /** |
| 176 | * Reads a byte from the stream and returns a <code>boolean</code> |
| 177 | * value of <code>true</code> if it is nonzero, <code>false</code> |
| 178 | * if it is zero. |
| 179 | * |
| 180 | * <p> The bit offset within the stream is reset to zero before |
| 181 | * the read occurs. |
| 182 | * |
| 183 | * @return a boolean value from the stream. |
| 184 | * |
| 185 | * @exception EOFException if the end of the stream is reached. |
| 186 | * @exception IOException if an I/O error occurs. |
| 187 | */ |
| 188 | boolean readBoolean() throws IOException; |
| 189 | |
| 190 | /** |
| 191 | * Reads a byte from the stream and returns it as a |
| 192 | * <code>byte</code> value. Byte values between <code>0x00</code> |
| 193 | * and <code>0x7f</code> represent integer values between |
| 194 | * <code>0</code> and <code>127</code>. Values between |
| 195 | * <code>0x80</code> and <code>0xff</code> represent negative |
| 196 | * values from <code>-128</code> to <code>/1</code>. |
| 197 | * |
| 198 | * <p> The bit offset within the stream is reset to zero before |
| 199 | * the read occurs. |
| 200 | * |
| 201 | * @return a signed byte value from the stream. |
| 202 | * |
| 203 | * @exception EOFException if the end of the stream is reached. |
| 204 | * @exception IOException if an I/O error occurs. |
| 205 | */ |
| 206 | byte readByte() throws IOException; |
| 207 | |
| 208 | /** |
| 209 | * Reads a byte from the stream, and (conceptually) converts it to |
| 210 | * an int, masks it with <code>0xff</code> in order to strip off |
| 211 | * any sign-extension bits, and returns it as a <code>byte</code> |
| 212 | * value. |
| 213 | * |
| 214 | * <p> Thus, byte values between <code>0x00</code> and |
| 215 | * <code>0x7f</code> are simply returned as integer values between |
| 216 | * <code>0</code> and <code>127</code>. Values between |
| 217 | * <code>0x80</code> and <code>0xff</code>, which normally |
| 218 | * represent negative <code>byte</code>values, will be mapped into |
| 219 | * positive integers between <code>128</code> and |
| 220 | * <code>255</code>. |
| 221 | * |
| 222 | * <p> The bit offset within the stream is reset to zero before |
| 223 | * the read occurs. |
| 224 | * |
| 225 | * @return an unsigned byte value from the stream. |
| 226 | * |
| 227 | * @exception EOFException if the end of the stream is reached. |
| 228 | * @exception IOException if an I/O error occurs. |
| 229 | */ |
| 230 | int readUnsignedByte() throws IOException; |
| 231 | |
| 232 | /** |
| 233 | * Reads two bytes from the stream, and (conceptually) |
| 234 | * concatenates them according to the current byte order, and |
| 235 | * returns the result as a <code>short</code> value. |
| 236 | * |
| 237 | * <p> The bit offset within the stream is reset to zero before |
| 238 | * the read occurs. |
| 239 | * |
| 240 | * @return a signed short value from the stream. |
| 241 | * |
| 242 | * @exception EOFException if the stream reaches the end before |
| 243 | * reading all the bytes. |
| 244 | * @exception IOException if an I/O error occurs. |
| 245 | * |
| 246 | * @see #getByteOrder |
| 247 | */ |
| 248 | short readShort() throws IOException; |
| 249 | |
| 250 | /** |
| 251 | * Reads two bytes from the stream, and (conceptually) |
| 252 | * concatenates them according to the current byte order, converts |
| 253 | * the resulting value to an <code>int</code>, masks it with |
| 254 | * <code>0xffff</code> in order to strip off any sign-extension |
| 255 | * buts, and returns the result as an unsigned <code>int</code> |
| 256 | * value. |
| 257 | * |
| 258 | * <p> The bit offset within the stream is reset to zero before |
| 259 | * the read occurs. |
| 260 | * |
| 261 | * @return an unsigned short value from the stream, as an int. |
| 262 | * |
| 263 | * @exception EOFException if the stream reaches the end before |
| 264 | * reading all the bytes. |
| 265 | * @exception IOException if an I/O error occurs. |
| 266 | * |
| 267 | * @see #getByteOrder |
| 268 | */ |
| 269 | int readUnsignedShort() throws IOException; |
| 270 | |
| 271 | /** |
| 272 | * Equivalent to <code>readUnsignedShort</code>, except that the |
| 273 | * result is returned using the <code>char</code> datatype. |
| 274 | * |
| 275 | * <p> The bit offset within the stream is reset to zero before |
| 276 | * the read occurs. |
| 277 | * |
| 278 | * @return an unsigned char value from the stream. |
| 279 | * |
| 280 | * @exception EOFException if the stream reaches the end before |
| 281 | * reading all the bytes. |
| 282 | * @exception IOException if an I/O error occurs. |
| 283 | * |
| 284 | * @see #readUnsignedShort |
| 285 | */ |
| 286 | char readChar() throws IOException; |
| 287 | |
| 288 | /** |
| 289 | * Reads 4 bytes from the stream, and (conceptually) concatenates |
| 290 | * them according to the current byte order and returns the result |
| 291 | * as an <code>int</code>. |
| 292 | * |
| 293 | * <p> The bit offset within the stream is ignored and treated as |
| 294 | * though it were zero. |
| 295 | * |
| 296 | * @return a signed int value from the stream. |
| 297 | * |
| 298 | * @exception EOFException if the stream reaches the end before |
| 299 | * reading all the bytes. |
| 300 | * @exception IOException if an I/O error occurs. |
| 301 | * |
| 302 | * @see #getByteOrder |
| 303 | */ |
| 304 | int readInt() throws IOException; |
| 305 | |
| 306 | /** |
| 307 | * Reads 4 bytes from the stream, and (conceptually) concatenates |
| 308 | * them according to the current byte order, converts the result |
| 309 | * to a long, masks it with <code>0xffffffffL</code> in order to |
| 310 | * strip off any sign-extension bits, and returns the result as an |
| 311 | * unsigned <code>long</code> value. |
| 312 | * |
| 313 | * <p> The bit offset within the stream is reset to zero before |
| 314 | * the read occurs. |
| 315 | * |
| 316 | * @return an unsigned int value from the stream, as a long. |
| 317 | * |
| 318 | * @exception EOFException if the stream reaches the end before |
| 319 | * reading all the bytes. |
| 320 | * @exception IOException if an I/O error occurs. |
| 321 | * |
| 322 | * @see #getByteOrder |
| 323 | */ |
| 324 | long readUnsignedInt() throws IOException; |
| 325 | |
| 326 | /** |
| 327 | * Reads 8 bytes from the stream, and (conceptually) concatenates |
| 328 | * them according to the current byte order and returns the result |
| 329 | * as a <code>long</code>. |
| 330 | * |
| 331 | * <p> The bit offset within the stream is reset to zero before |
| 332 | * the read occurs. |
| 333 | * |
| 334 | * @return a signed long value from the stream. |
| 335 | * |
| 336 | * @exception EOFException if the stream reaches the end before |
| 337 | * reading all the bytes. |
| 338 | * @exception IOException if an I/O error occurs. |
| 339 | * |
| 340 | * @see #getByteOrder |
| 341 | */ |
| 342 | long readLong() throws IOException; |
| 343 | |
| 344 | /** |
| 345 | * Reads 4 bytes from the stream, and (conceptually) concatenates |
| 346 | * them according to the current byte order and returns the result |
| 347 | * as a <code>float</code>. |
| 348 | * |
| 349 | * <p> The bit offset within the stream is reset to zero before |
| 350 | * the read occurs. |
| 351 | * |
| 352 | * @return a float value from the stream. |
| 353 | * |
| 354 | * @exception EOFException if the stream reaches the end before |
| 355 | * reading all the bytes. |
| 356 | * @exception IOException if an I/O error occurs. |
| 357 | * |
| 358 | * @see #getByteOrder |
| 359 | */ |
| 360 | float readFloat() throws IOException; |
| 361 | |
| 362 | /** |
| 363 | * Reads 8 bytes from the stream, and (conceptually) concatenates |
| 364 | * them according to the current byte order and returns the result |
| 365 | * as a <code>double</code>. |
| 366 | * |
| 367 | * <p> The bit offset within the stream is reset to zero before |
| 368 | * the read occurs. |
| 369 | * |
| 370 | * @return a double value from the stream. |
| 371 | * |
| 372 | * @exception EOFException if the stream reaches the end before |
| 373 | * reading all the bytes. |
| 374 | * @exception IOException if an I/O error occurs. |
| 375 | * |
| 376 | * @see #getByteOrder |
| 377 | */ |
| 378 | double readDouble() throws IOException; |
| 379 | |
| 380 | /** |
| 381 | * Reads the next line of text from the input stream. It reads |
| 382 | * successive bytes, converting each byte separately into a |
| 383 | * character, until it encounters a line terminator or end of |
| 384 | * file; the characters read are then returned as a |
| 385 | * <code>String</code>. Note that because this method processes |
| 386 | * bytes, it does not support input of the full Unicode character |
| 387 | * set. |
| 388 | * |
| 389 | * <p> If end of file is encountered before even one byte can be |
| 390 | * read, then <code>null</code> is returned. Otherwise, each byte |
| 391 | * that is read is converted to type <code>char</code> by |
| 392 | * zero-extension. If the character <code>'\n'</code> is |
| 393 | * encountered, it is discarded and reading ceases. If the |
| 394 | * character <code>'\r'</code> is encountered, it is discarded |
| 395 | * and, if the following byte converts  to the character |
| 396 | * <code>'\n'</code>, then that is discarded also; reading then |
| 397 | * ceases. If end of file is encountered before either of the |
| 398 | * characters <code>'\n'</code> and <code>'\r'</code> is |
| 399 | * encountered, reading ceases. Once reading has ceased, a |
| 400 | * <code>String</code> is returned that contains all the |
| 401 | * characters read and not discarded, taken in order. Note that |
| 402 | * every character in this string will have a value less than |
| 403 | * <code>\u0100</code>, that is, <code>(char)256</code>. |
| 404 | * |
| 405 | * <p> The bit offset within the stream is reset to zero before |
| 406 | * the read occurs. |
| 407 | * |
| 408 | * @return a String containing a line of text from the stream. |
| 409 | * |
| 410 | * @exception IOException if an I/O error occurs. |
| 411 | */ |
| 412 | String readLine() throws IOException; |
| 413 | |
| 414 | /** |
| 415 | * Reads in a string that has been encoded using a |
| 416 | * <a href="../../../java/io/DataInput.html#modified-utf-8">modified |
| 417 | * UTF-8</a> |
| 418 | * format. The general contract of <code>readUTF</code> is that |
| 419 | * it reads a representation of a Unicode character string encoded |
| 420 | * in modified UTF-8 format; this string of characters is |
| 421 | * then returned as a <code>String</code>. |
| 422 | * |
| 423 | * <p> First, two bytes are read and used to construct an unsigned |
| 424 | * 16-bit integer in the manner of the |
| 425 | * <code>readUnsignedShort</code> method, using network byte order |
| 426 | * (regardless of the current byte order setting). This integer |
| 427 | * value is called the <i>UTF length</i> and specifies the number |
| 428 | * of additional bytes to be read. These bytes are then converted |
| 429 | * to characters by considering them in groups. The length of each |
| 430 | * group is computed from the value of the first byte of the |
| 431 | * group. The byte following a group, if any, is the first byte of |
| 432 | * the next group. |
| 433 | * |
| 434 | * <p> If the first byte of a group matches the bit pattern |
| 435 | * <code>0xxxxxxx</code> (where <code>x</code> means "may be |
| 436 | * <code>0</code> or <code>1</code>"), then the group consists of |
| 437 | * just that byte. The byte is zero-extended to form a character. |
| 438 | * |
| 439 | * <p> If the first byte of a group matches the bit pattern |
| 440 | * <code>110xxxxx</code>, then the group consists of that byte |
| 441 | * <code>a</code> and a second byte <code>b</code>. If there is no |
| 442 | * byte <code>b</code> (because byte <code>a</code> was the last |
| 443 | * of the bytes to be read), or if byte <code>b</code> does not |
| 444 | * match the bit pattern <code>10xxxxxx</code>, then a |
| 445 | * <code>UTFDataFormatException</code> is thrown. Otherwise, the |
| 446 | * group is converted to the character: |
| 447 | * |
| 448 | * <p> <pre><code> |
| 449 | * (char)(((a& 0x1F) << 6) | (b & 0x3F)) |
| 450 | * </code></pre> |
| 451 | * |
| 452 | * If the first byte of a group matches the bit pattern |
| 453 | * <code>1110xxxx</code>, then the group consists of that byte |
| 454 | * <code>a</code> and two more bytes <code>b</code> and |
| 455 | * <code>c</code>. If there is no byte <code>c</code> (because |
| 456 | * byte <code>a</code> was one of the last two of the bytes to be |
| 457 | * read), or either byte <code>b</code> or byte <code>c</code> |
| 458 | * does not match the bit pattern <code>10xxxxxx</code>, then a |
| 459 | * <code>UTFDataFormatException</code> is thrown. Otherwise, the |
| 460 | * group is converted to the character: |
| 461 | * |
| 462 | * <p> <pre><code> |
| 463 | * (char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F)) |
| 464 | * </code></pre> |
| 465 | * |
| 466 | * If the first byte of a group matches the pattern |
| 467 | * <code>1111xxxx</code> or the pattern <code>10xxxxxx</code>, |
| 468 | * then a <code>UTFDataFormatException</code> is thrown. |
| 469 | * |
| 470 | * <p> If end of file is encountered at any time during this |
| 471 | * entire process, then an <code>EOFException</code> is thrown. |
| 472 | * |
| 473 | * <p> After every group has been converted to a character by this |
| 474 | * process, the characters are gathered, in the same order in |
| 475 | * which their corresponding groups were read from the input |
| 476 | * stream, to form a <code>String</code>, which is returned. |
| 477 | * |
| 478 | * <p> The current byte order setting is ignored. |
| 479 | * |
| 480 | * <p> The bit offset within the stream is reset to zero before |
| 481 | * the read occurs. |
| 482 | * |
| 483 | * <p><strong>Note:</strong> This method should not be used in |
| 484 | * the implementation of image formats that use standard UTF-8, |
| 485 | * because the modified UTF-8 used here is incompatible with |
| 486 | * standard UTF-8. |
| 487 | * |
| 488 | * @return a String read from the stream. |
| 489 | * |
| 490 | * @exception EOFException if this stream reaches the end |
| 491 | * before reading all the bytes. |
| 492 | * @exception UTFDataFormatException if the bytes do not represent a |
| 493 | * valid modified UTF-8 encoding of a string. |
| 494 | * @exception IOException if an I/O error occurs. |
| 495 | */ |
| 496 | String readUTF() throws IOException; |
| 497 | |
| 498 | /** |
| 499 | * Reads <code>len</code> bytes from the stream, and stores them |
| 500 | * into <code>b</code> starting at index <code>off</code>. |
| 501 | * If the end of the stream is reached, an <code>EOFException</code> |
| 502 | * will be thrown. |
| 503 | * |
| 504 | * <p> The bit offset within the stream is reset to zero before |
| 505 | * the read occurs. |
| 506 | * |
| 507 | * @param b an array of bytes to be written to. |
| 508 | * @param off the starting position within <code>b</code> to write to. |
| 509 | * @param len the maximum number of <code>byte</code>s to read. |
| 510 | * |
| 511 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 512 | * negative, <code>len</code> is negative, or <code>off + |
| 513 | * len</code> is greater than <code>b.length</code>. |
| 514 | * @exception NullPointerException if <code>b</code> is |
| 515 | * <code>null</code>. |
| 516 | * @exception EOFException if the stream reaches the end before |
| 517 | * reading all the bytes. |
| 518 | * @exception IOException if an I/O error occurs. |
| 519 | */ |
| 520 | void readFully(byte[] b, int off, int len) throws IOException; |
| 521 | |
| 522 | /** |
| 523 | * Reads <code>b.length</code> bytes from the stream, and stores them |
| 524 | * into <code>b</code> starting at index <code>0</code>. |
| 525 | * If the end of the stream is reached, an <code>EOFException</code> |
| 526 | * will be thrown. |
| 527 | * |
| 528 | * <p> The bit offset within the stream is reset to zero before |
| 529 | * the read occurs. |
| 530 | * |
| 531 | * @param b an array of <code>byte</code>s. |
| 532 | * |
| 533 | * @exception NullPointerException if <code>b</code> is |
| 534 | * <code>null</code>. |
| 535 | * @exception EOFException if the stream reaches the end before |
| 536 | * reading all the bytes. |
| 537 | * @exception IOException if an I/O error occurs. |
| 538 | */ |
| 539 | void readFully(byte[] b) throws IOException; |
| 540 | |
| 541 | /** |
| 542 | * Reads <code>len</code> shorts (signed 16-bit integers) from the |
| 543 | * stream according to the current byte order, and |
| 544 | * stores them into <code>s</code> starting at index |
| 545 | * <code>off</code>. If the end of the stream is reached, an |
| 546 | * <code>EOFException</code> will be thrown. |
| 547 | * |
| 548 | * <p> The bit offset within the stream is reset to zero before |
| 549 | * the read occurs. |
| 550 | * |
| 551 | * @param s an array of shorts to be written to. |
| 552 | * @param off the starting position withinb to write to. |
| 553 | * @param len the maximum number of <code>short</code>s to read. |
| 554 | * |
| 555 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 556 | * negative, <code>len</code> is negative, or <code>off + |
| 557 | * len</code> is greater than <code>s.length</code>. |
| 558 | * @exception NullPointerException if <code>s</code> is |
| 559 | * <code>null</code>. |
| 560 | * @exception EOFException if the stream reaches the end before |
| 561 | * reading all the bytes. |
| 562 | * @exception IOException if an I/O error occurs. |
| 563 | */ |
| 564 | void readFully(short[] s, int off, int len) throws IOException; |
| 565 | |
| 566 | /** |
| 567 | * Reads <code>len</code> chars (unsigned 16-bit integers) from the |
| 568 | * stream according to the current byte order, and |
| 569 | * stores them into <code>c</code> starting at index |
| 570 | * <code>off</code>. If the end of the stream is reached, an |
| 571 | * <code>EOFException</code> will be thrown. |
| 572 | * |
| 573 | * <p> The bit offset within the stream is reset to zero before |
| 574 | * the read occurs. |
| 575 | * |
| 576 | * @param c an array of chars to be written to. |
| 577 | * @param off the starting position withinb to write to. |
| 578 | * @param len the maximum number of <code>char</code>s to read. |
| 579 | * |
| 580 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 581 | * negative, <code>len</code> is negative, or <code>off + |
| 582 | * len</code> is greater than <code>c.length</code>. |
| 583 | * @exception NullPointerException if <code>c</code> is |
| 584 | * <code>null</code>. |
| 585 | * @exception EOFException if the stream reaches the end before |
| 586 | * reading all the bytes. |
| 587 | * @exception IOException if an I/O error occurs. |
| 588 | */ |
| 589 | void readFully(char[] c, int off, int len) throws IOException; |
| 590 | |
| 591 | /** |
| 592 | * Reads <code>len</code> ints (signed 32-bit integers) from the |
| 593 | * stream according to the current byte order, and |
| 594 | * stores them into <code>i</code> starting at index |
| 595 | * <code>off</code>. If the end of the stream is reached, an |
| 596 | * <code>EOFException</code> will be thrown. |
| 597 | * |
| 598 | * <p> The bit offset within the stream is reset to zero before |
| 599 | * the read occurs. |
| 600 | * |
| 601 | * @param i an array of ints to be written to. |
| 602 | * @param off the starting position withinb to write to. |
| 603 | * @param len the maximum number of <code>int</code>s to read. |
| 604 | * |
| 605 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 606 | * negative, <code>len</code> is negative, or <code>off + |
| 607 | * len</code> is greater than <code>i.length</code>. |
| 608 | * @exception NullPointerException if <code>i</code> is |
| 609 | * <code>null</code>. |
| 610 | * @exception EOFException if the stream reaches the end before |
| 611 | * reading all the bytes. |
| 612 | * @exception IOException if an I/O error occurs. |
| 613 | */ |
| 614 | void readFully(int[] i, int off, int len) throws IOException; |
| 615 | |
| 616 | /** |
| 617 | * Reads <code>len</code> longs (signed 64-bit integers) from the |
| 618 | * stream according to the current byte order, and |
| 619 | * stores them into <code>l</code> starting at index |
| 620 | * <code>off</code>. If the end of the stream is reached, an |
| 621 | * <code>EOFException</code> will be thrown. |
| 622 | * |
| 623 | * <p> The bit offset within the stream is reset to zero before |
| 624 | * the read occurs. |
| 625 | * |
| 626 | * @param l an array of longs to be written to. |
| 627 | * @param off the starting position withinb to write to. |
| 628 | * @param len the maximum number of <code>long</code>s to read. |
| 629 | * |
| 630 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 631 | * negative, <code>len</code> is negative, or <code>off + |
| 632 | * len</code> is greater than <code>l.length</code>. |
| 633 | * @exception NullPointerException if <code>l</code> is |
| 634 | * <code>null</code>. |
| 635 | * @exception EOFException if the stream reaches the end before |
| 636 | * reading all the bytes. |
| 637 | * @exception IOException if an I/O error occurs. |
| 638 | */ |
| 639 | void readFully(long[] l, int off, int len) throws IOException; |
| 640 | |
| 641 | /** |
| 642 | * Reads <code>len</code> floats (32-bit IEEE single-precision |
| 643 | * floats) from the stream according to the current byte order, |
| 644 | * and stores them into <code>f</code> starting at |
| 645 | * index <code>off</code>. If the end of the stream is reached, |
| 646 | * an <code>EOFException</code> will be thrown. |
| 647 | * |
| 648 | * <p> The bit offset within the stream is reset to zero before |
| 649 | * the read occurs. |
| 650 | * |
| 651 | * @param f an array of floats to be written to. |
| 652 | * @param off the starting position withinb to write to. |
| 653 | * @param len the maximum number of <code>float</code>s to read. |
| 654 | * |
| 655 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 656 | * negative, <code>len</code> is negative, or <code>off + |
| 657 | * len</code> is greater than <code>f.length</code>. |
| 658 | * @exception NullPointerException if <code>f</code> is |
| 659 | * <code>null</code>. |
| 660 | * @exception EOFException if the stream reaches the end before |
| 661 | * reading all the bytes. |
| 662 | * @exception IOException if an I/O error occurs. |
| 663 | */ |
| 664 | void readFully(float[] f, int off, int len) throws IOException; |
| 665 | |
| 666 | /** |
| 667 | * Reads <code>len</code> doubles (64-bit IEEE double-precision |
| 668 | * floats) from the stream according to the current byte order, |
| 669 | * and stores them into <code>d</code> starting at |
| 670 | * index <code>off</code>. If the end of the stream is reached, |
| 671 | * an <code>EOFException</code> will be thrown. |
| 672 | * |
| 673 | * <p> The bit offset within the stream is reset to zero before |
| 674 | * the read occurs. |
| 675 | * |
| 676 | * @param d an array of doubles to be written to. |
| 677 | * @param off the starting position withinb to write to. |
| 678 | * @param len the maximum number of <code>double</code>s to read. |
| 679 | * |
| 680 | * @exception IndexOutOfBoundsException if <code>off</code> is |
| 681 | * negative, <code>len</code> is negative, or <code>off + |
| 682 | * len</code> is greater than <code>d.length</code>. |
| 683 | * @exception NullPointerException if <code>d</code> is |
| 684 | * <code>null</code>. |
| 685 | * @exception EOFException if the stream reaches the end before |
| 686 | * reading all the bytes. |
| 687 | * @exception IOException if an I/O error occurs. |
| 688 | */ |
| 689 | void readFully(double[] d, int off, int len) throws IOException; |
| 690 | |
| 691 | /** |
| 692 | * Returns the current byte position of the stream. The next read |
| 693 | * will take place starting at this offset. |
| 694 | * |
| 695 | * @return a long containing the position of the stream. |
| 696 | * |
| 697 | * @exception IOException if an I/O error occurs. |
| 698 | */ |
| 699 | long getStreamPosition() throws IOException; |
| 700 | |
| 701 | /** |
| 702 | * Returns the current bit offset, as an integer between 0 and 7, |
| 703 | * inclusive. The bit offset is updated implicitly by calls to |
| 704 | * the <code>readBits</code> method. A value of 0 indicates the |
| 705 | * most-significant bit, and a value of 7 indicates the least |
| 706 | * significant bit, of the byte being read. |
| 707 | * |
| 708 | * <p> The bit offset is set to 0 when a stream is first |
| 709 | * opened, and is reset to 0 by calls to <code>seek</code>, |
| 710 | * <code>skipBytes</code>, or any <code>read</code> or |
| 711 | * <code>readFully</code> method. |
| 712 | * |
| 713 | * @return an <code>int</code> containing the bit offset between |
| 714 | * 0 and 7, inclusive. |
| 715 | * |
| 716 | * @exception IOException if an I/O error occurs. |
| 717 | * |
| 718 | * @see #setBitOffset |
| 719 | */ |
| 720 | int getBitOffset() throws IOException; |
| 721 | |
| 722 | /** |
| 723 | * Sets the bit offset to an integer between 0 and 7, inclusive. |
| 724 | * The byte offset within the stream, as returned by |
| 725 | * <code>getStreamPosition</code>, is left unchanged. |
| 726 | * A value of 0 indicates the |
| 727 | * most-significant bit, and a value of 7 indicates the least |
| 728 | * significant bit, of the byte being read. |
| 729 | * |
| 730 | * @param bitOffset the desired offset, as an <code>int</code> |
| 731 | * between 0 and 7, inclusive. |
| 732 | * |
| 733 | * @exception IllegalArgumentException if <code>bitOffset</code> |
| 734 | * is not between 0 and 7, inclusive. |
| 735 | * @exception IOException if an I/O error occurs. |
| 736 | * |
| 737 | * @see #getBitOffset |
| 738 | */ |
| 739 | void setBitOffset(int bitOffset) throws IOException; |
| 740 | |
| 741 | /** |
| 742 | * Reads a single bit from the stream and returns it as an |
| 743 | * <code>int</code> with the value <code>0</code> or |
| 744 | * <code>1</code>. The bit offset is advanced by one and reduced |
| 745 | * modulo 8. |
| 746 | * |
| 747 | * @return an <code>int</code> containing the value <code>0</code> |
| 748 | * or <code>1</code>. |
| 749 | * |
| 750 | * @exception EOFException if the stream reaches the end before |
| 751 | * reading all the bits. |
| 752 | * @exception IOException if an I/O error occurs. |
| 753 | */ |
| 754 | int readBit() throws IOException; |
| 755 | |
| 756 | /** |
| 757 | * Reads a bitstring from the stream and returns it as a |
| 758 | * <code>long</code>, with the first bit read becoming the most |
| 759 | * significant bit of the output. The read starts within the byte |
| 760 | * indicated by <code>getStreamPosition</code>, at the bit given |
| 761 | * by <code>getBitOffset</code>. The bit offset is advanced by |
| 762 | * <code>numBits</code> and reduced modulo 8. |
| 763 | * |
| 764 | * <p> The byte order of the stream has no effect on this |
| 765 | * method. The return value of this method is constructed as |
| 766 | * though the bits were read one at a time, and shifted into |
| 767 | * the right side of the return value, as shown by the following |
| 768 | * pseudo-code: |
| 769 | * |
| 770 | * <pre> |
| 771 | * long accum = 0L; |
| 772 | * for (int i = 0; i < numBits; i++) { |
| 773 | * accum <<= 1; // Shift left one bit to make room |
| 774 | * accum |= readBit(); |
| 775 | * } |
| 776 | * </pre> |
| 777 | * |
| 778 | * Note that the result of <code>readBits(32)</code> may thus not |
| 779 | * be equal to that of <code>readInt()</code> if a reverse network |
| 780 | * byte order is being used (i.e., <code>getByteOrder() == |
| 781 | * false</code>). |
| 782 | * |
| 783 | * <p> If the end of the stream is encountered before all the bits |
| 784 | * have been read, an <code>EOFException</code> is thrown. |
| 785 | * |
| 786 | * @param numBits the number of bits to read, as an <code>int</code> |
| 787 | * between 0 and 64, inclusive. |
| 788 | * @return the bitstring, as a <code>long</code> with the last bit |
| 789 | * read stored in the least significant bit. |
| 790 | * |
| 791 | * @exception IllegalArgumentException if <code>numBits</code> |
| 792 | * is not between 0 and 64, inclusive. |
| 793 | * @exception EOFException if the stream reaches the end before |
| 794 | * reading all the bits. |
| 795 | * @exception IOException if an I/O error occurs. |
| 796 | */ |
| 797 | long readBits(int numBits) throws IOException; |
| 798 | |
| 799 | /** |
| 800 | * Returns the total length of the stream, if known. Otherwise, |
| 801 | * <code>-1</code> is returned. |
| 802 | * |
| 803 | * @return a <code>long</code> containing the length of the |
| 804 | * stream, if known, or else <code>-1</code>. |
| 805 | * |
| 806 | * @exception IOException if an I/O error occurs. |
| 807 | */ |
| 808 | long length() throws IOException; |
| 809 | |
| 810 | /** |
| 811 | * Moves the stream position forward by a given number of bytes. It |
| 812 | * is possible that this method will only be able to skip forward |
| 813 | * by a smaller number of bytes than requested, for example if the |
| 814 | * end of the stream is reached. In all cases, the actual number |
| 815 | * of bytes skipped is returned. The bit offset is set to zero |
| 816 | * prior to advancing the position. |
| 817 | * |
| 818 | * @param n an <code>int</code> containing the number of bytes to |
| 819 | * be skipped. |
| 820 | * |
| 821 | * @return an <code>int</code> representing the number of bytes skipped. |
| 822 | * |
| 823 | * @exception IOException if an I/O error occurs. |
| 824 | */ |
| 825 | int skipBytes(int n) throws IOException; |
| 826 | |
| 827 | /** |
| 828 | * Moves the stream position forward by a given number of bytes. |
| 829 | * This method is identical to <code>skipBytes(int)</code> except |
| 830 | * that it allows for a larger skip distance. |
| 831 | * |
| 832 | * @param n a <code>long</code> containing the number of bytes to |
| 833 | * be skipped. |
| 834 | * |
| 835 | * @return a <code>long</code> representing the number of bytes |
| 836 | * skipped. |
| 837 | * |
| 838 | * @exception IOException if an I/O error occurs. |
| 839 | */ |
| 840 | long skipBytes(long n) throws IOException; |
| 841 | |
| 842 | /** |
| 843 | * Sets the current stream position to the desired location. The |
| 844 | * next read will occur at this location. The bit offset is set |
| 845 | * to 0. |
| 846 | * |
| 847 | * <p> An <code>IndexOutOfBoundsException</code> will be thrown if |
| 848 | * <code>pos</code> is smaller than the flushed position (as |
| 849 | * returned by <code>getflushedPosition</code>). |
| 850 | * |
| 851 | * <p> It is legal to seek past the end of the file; an |
| 852 | * <code>EOFException</code> will be thrown only if a read is |
| 853 | * performed. |
| 854 | * |
| 855 | * @param pos a <code>long</code> containing the desired file |
| 856 | * pointer position. |
| 857 | * |
| 858 | * @exception IndexOutOfBoundsException if <code>pos</code> is smaller |
| 859 | * than the flushed position. |
| 860 | * @exception IOException if any other I/O error occurs. |
| 861 | */ |
| 862 | void seek(long pos) throws IOException; |
| 863 | |
| 864 | /** |
| 865 | * Marks a position in the stream to be returned to by a |
| 866 | * subsequent call to <code>reset</code>. Unlike a standard |
| 867 | * <code>InputStream</code>, all <code>ImageInputStream</code>s |
| 868 | * support marking. Additionally, calls to <code>mark</code> and |
| 869 | * <code>reset</code> may be nested arbitrarily. |
| 870 | * |
| 871 | * <p> Unlike the <code>mark</code> methods declared by the |
| 872 | * <code>Reader</code> and <code>InputStream</code> interfaces, no |
| 873 | * <code>readLimit</code> parameter is used. An arbitrary amount |
| 874 | * of data may be read following the call to <code>mark</code>. |
| 875 | * |
| 876 | * <p> The bit position used by the <code>readBits</code> method |
| 877 | * is saved and restored by each pair of calls to |
| 878 | * <code>mark</code> and <code>reset</code>. |
| 879 | * |
| 880 | * <p> Note that it is valid for an <code>ImageReader</code> to call |
| 881 | * <code>flushBefore</code> as part of a read operation. |
| 882 | * Therefore, if an application calls <code>mark</code> prior to |
| 883 | * passing that stream to an <code>ImageReader</code>, the application |
| 884 | * should not assume that the marked position will remain valid after |
| 885 | * the read operation has completed. |
| 886 | */ |
| 887 | void mark(); |
| 888 | |
| 889 | /** |
| 890 | * Returns the stream pointer to its previous position, including |
| 891 | * the bit offset, at the time of the most recent unmatched call |
| 892 | * to <code>mark</code>. |
| 893 | * |
| 894 | * <p> Calls to <code>reset</code> without a corresponding call |
| 895 | * to <code>mark</code> have no effect. |
| 896 | * |
| 897 | * <p> An <code>IOException</code> will be thrown if the previous |
| 898 | * marked position lies in the discarded portion of the stream. |
| 899 | * |
| 900 | * @exception IOException if an I/O error occurs. |
| 901 | */ |
| 902 | void reset() throws IOException; |
| 903 | |
| 904 | /** |
| 905 | * Discards the initial portion of the stream prior to the |
| 906 | * indicated postion. Attempting to seek to an offset within the |
| 907 | * flushed portion of the stream will result in an |
| 908 | * <code>IndexOutOfBoundsException</code>. |
| 909 | * |
| 910 | * <p> Calling <code>flushBefore</code> may allow classes |
| 911 | * implementing this interface to free up resources such as memory |
| 912 | * or disk space that are being used to store data from the |
| 913 | * stream. |
| 914 | * |
| 915 | * @param pos a <code>long</code> containing the length of the |
| 916 | * stream prefix that may be flushed. |
| 917 | * |
| 918 | * @exception IndexOutOfBoundsException if <code>pos</code> lies |
| 919 | * in the flushed portion of the stream or past the current stream |
| 920 | * position. |
| 921 | * @exception IOException if an I/O error occurs. |
| 922 | */ |
| 923 | void flushBefore(long pos) throws IOException; |
| 924 | |
| 925 | /** |
| 926 | * Discards the initial position of the stream prior to the current |
| 927 | * stream position. Equivalent to |
| 928 | * <code>flushBefore(getStreamPosition())</code>. |
| 929 | * |
| 930 | * @exception IOException if an I/O error occurs. |
| 931 | */ |
| 932 | void flush() throws IOException; |
| 933 | |
| 934 | /** |
| 935 | * Returns the earliest position in the stream to which seeking |
| 936 | * may be performed. The returned value will be the maximum of |
| 937 | * all values passed into previous calls to |
| 938 | * <code>flushBefore</code>. |
| 939 | * |
| 940 | * @return the earliest legal position for seeking, as a |
| 941 | * <code>long</code>. |
| 942 | */ |
| 943 | long getFlushedPosition(); |
| 944 | |
| 945 | /** |
| 946 | * Returns <code>true</code> if this <code>ImageInputStream</code> |
| 947 | * caches data itself in order to allow seeking backwards. |
| 948 | * Applications may consult this in order to decide how frequently, |
| 949 | * or whether, to flush in order to conserve cache resources. |
| 950 | * |
| 951 | * @return <code>true</code> if this <code>ImageInputStream</code> |
| 952 | * caches data. |
| 953 | * |
| 954 | * @see #isCachedMemory |
| 955 | * @see #isCachedFile |
| 956 | */ |
| 957 | boolean isCached(); |
| 958 | |
| 959 | /** |
| 960 | * Returns <code>true</code> if this <code>ImageInputStream</code> |
| 961 | * caches data itself in order to allow seeking backwards, and |
| 962 | * the cache is kept in main memory. Applications may consult |
| 963 | * this in order to decide how frequently, or whether, to flush |
| 964 | * in order to conserve cache resources. |
| 965 | * |
| 966 | * @return <code>true</code> if this <code>ImageInputStream</code> |
| 967 | * caches data in main memory. |
| 968 | * |
| 969 | * @see #isCached |
| 970 | * @see #isCachedFile |
| 971 | */ |
| 972 | boolean isCachedMemory(); |
| 973 | |
| 974 | /** |
| 975 | * Returns <code>true</code> if this <code>ImageInputStream</code> |
| 976 | * caches data itself in order to allow seeking backwards, and |
| 977 | * the cache is kept in a temporary file. Applications may consult |
| 978 | * this in order to decide how frequently, or whether, to flush |
| 979 | * in order to conserve cache resources. |
| 980 | * |
| 981 | * @return <code>true</code> if this <code>ImageInputStream</code> |
| 982 | * caches data in a temporary file. |
| 983 | * |
| 984 | * @see #isCached |
| 985 | * @see #isCachedMemory |
| 986 | */ |
| 987 | boolean isCachedFile(); |
| 988 | |
| 989 | /** |
| 990 | * Closes the stream. Attempts to access a stream that has been |
| 991 | * closed may result in <code>IOException</code>s or incorrect |
| 992 | * behavior. Calling this method may allow classes implementing |
| 993 | * this interface to release resources associated with the stream |
| 994 | * such as memory, disk space, or file descriptors. |
| 995 | * |
| 996 | * @exception IOException if an I/O error occurs. |
| 997 | */ |
| 998 | void close() throws IOException; |
| 999 | } |