J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1994-2006 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 java.io; |
| 27 | |
| 28 | /** |
| 29 | * A data input stream lets an application read primitive Java data |
| 30 | * types from an underlying input stream in a machine-independent |
| 31 | * way. An application uses a data output stream to write data that |
| 32 | * can later be read by a data input stream. |
| 33 | * <p> |
| 34 | * DataInputStream is not necessarily safe for multithreaded access. |
| 35 | * Thread safety is optional and is the responsibility of users of |
| 36 | * methods in this class. |
| 37 | * |
| 38 | * @author Arthur van Hoff |
| 39 | * @see java.io.DataOutputStream |
| 40 | * @since JDK1.0 |
| 41 | */ |
| 42 | public |
| 43 | class DataInputStream extends FilterInputStream implements DataInput { |
| 44 | |
| 45 | /** |
| 46 | * Creates a DataInputStream that uses the specified |
| 47 | * underlying InputStream. |
| 48 | * |
| 49 | * @param in the specified input stream |
| 50 | */ |
| 51 | public DataInputStream(InputStream in) { |
| 52 | super(in); |
| 53 | } |
| 54 | |
| 55 | /** |
| 56 | * working arrays initialized on demand by readUTF |
| 57 | */ |
| 58 | private byte bytearr[] = new byte[80]; |
| 59 | private char chararr[] = new char[80]; |
| 60 | |
| 61 | /** |
| 62 | * Reads some number of bytes from the contained input stream and |
| 63 | * stores them into the buffer array <code>b</code>. The number of |
| 64 | * bytes actually read is returned as an integer. This method blocks |
| 65 | * until input data is available, end of file is detected, or an |
| 66 | * exception is thrown. |
| 67 | * |
| 68 | * <p>If <code>b</code> is null, a <code>NullPointerException</code> is |
| 69 | * thrown. If the length of <code>b</code> is zero, then no bytes are |
| 70 | * read and <code>0</code> is returned; otherwise, there is an attempt |
| 71 | * to read at least one byte. If no byte is available because the |
| 72 | * stream is at end of file, the value <code>-1</code> is returned; |
| 73 | * otherwise, at least one byte is read and stored into <code>b</code>. |
| 74 | * |
| 75 | * <p>The first byte read is stored into element <code>b[0]</code>, the |
| 76 | * next one into <code>b[1]</code>, and so on. The number of bytes read |
| 77 | * is, at most, equal to the length of <code>b</code>. Let <code>k</code> |
| 78 | * be the number of bytes actually read; these bytes will be stored in |
| 79 | * elements <code>b[0]</code> through <code>b[k-1]</code>, leaving |
| 80 | * elements <code>b[k]</code> through <code>b[b.length-1]</code> |
| 81 | * unaffected. |
| 82 | * |
| 83 | * <p>The <code>read(b)</code> method has the same effect as: |
| 84 | * <blockquote><pre> |
| 85 | * read(b, 0, b.length) |
| 86 | * </pre></blockquote> |
| 87 | * |
| 88 | * @param b the buffer into which the data is read. |
| 89 | * @return the total number of bytes read into the buffer, or |
| 90 | * <code>-1</code> if there is no more data because the end |
| 91 | * of the stream has been reached. |
| 92 | * @exception IOException if the first byte cannot be read for any reason |
| 93 | * other than end of file, the stream has been closed and the underlying |
| 94 | * input stream does not support reading after close, or another I/O |
| 95 | * error occurs. |
| 96 | * @see java.io.FilterInputStream#in |
| 97 | * @see java.io.InputStream#read(byte[], int, int) |
| 98 | */ |
| 99 | public final int read(byte b[]) throws IOException { |
| 100 | return in.read(b, 0, b.length); |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * Reads up to <code>len</code> bytes of data from the contained |
| 105 | * input stream into an array of bytes. An attempt is made to read |
| 106 | * as many as <code>len</code> bytes, but a smaller number may be read, |
| 107 | * possibly zero. The number of bytes actually read is returned as an |
| 108 | * integer. |
| 109 | * |
| 110 | * <p> This method blocks until input data is available, end of file is |
| 111 | * detected, or an exception is thrown. |
| 112 | * |
| 113 | * <p> If <code>len</code> is zero, then no bytes are read and |
| 114 | * <code>0</code> is returned; otherwise, there is an attempt to read at |
| 115 | * least one byte. If no byte is available because the stream is at end of |
| 116 | * file, the value <code>-1</code> is returned; otherwise, at least one |
| 117 | * byte is read and stored into <code>b</code>. |
| 118 | * |
| 119 | * <p> The first byte read is stored into element <code>b[off]</code>, the |
| 120 | * next one into <code>b[off+1]</code>, and so on. The number of bytes read |
| 121 | * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of |
| 122 | * bytes actually read; these bytes will be stored in elements |
| 123 | * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>, |
| 124 | * leaving elements <code>b[off+</code><i>k</i><code>]</code> through |
| 125 | * <code>b[off+len-1]</code> unaffected. |
| 126 | * |
| 127 | * <p> In every case, elements <code>b[0]</code> through |
| 128 | * <code>b[off]</code> and elements <code>b[off+len]</code> through |
| 129 | * <code>b[b.length-1]</code> are unaffected. |
| 130 | * |
| 131 | * @param b the buffer into which the data is read. |
| 132 | * @param off the start offset in the destination array <code>b</code> |
| 133 | * @param len the maximum number of bytes read. |
| 134 | * @return the total number of bytes read into the buffer, or |
| 135 | * <code>-1</code> if there is no more data because the end |
| 136 | * of the stream has been reached. |
| 137 | * @exception NullPointerException If <code>b</code> is <code>null</code>. |
| 138 | * @exception IndexOutOfBoundsException If <code>off</code> is negative, |
| 139 | * <code>len</code> is negative, or <code>len</code> is greater than |
| 140 | * <code>b.length - off</code> |
| 141 | * @exception IOException if the first byte cannot be read for any reason |
| 142 | * other than end of file, the stream has been closed and the underlying |
| 143 | * input stream does not support reading after close, or another I/O |
| 144 | * error occurs. |
| 145 | * @see java.io.FilterInputStream#in |
| 146 | * @see java.io.InputStream#read(byte[], int, int) |
| 147 | */ |
| 148 | public final int read(byte b[], int off, int len) throws IOException { |
| 149 | return in.read(b, off, len); |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * See the general contract of the <code>readFully</code> |
| 154 | * method of <code>DataInput</code>. |
| 155 | * <p> |
| 156 | * Bytes |
| 157 | * for this operation are read from the contained |
| 158 | * input stream. |
| 159 | * |
| 160 | * @param b the buffer into which the data is read. |
| 161 | * @exception EOFException if this input stream reaches the end before |
| 162 | * reading all the bytes. |
| 163 | * @exception IOException the stream has been closed and the contained |
| 164 | * input stream does not support reading after close, or |
| 165 | * another I/O error occurs. |
| 166 | * @see java.io.FilterInputStream#in |
| 167 | */ |
| 168 | public final void readFully(byte b[]) throws IOException { |
| 169 | readFully(b, 0, b.length); |
| 170 | } |
| 171 | |
| 172 | /** |
| 173 | * See the general contract of the <code>readFully</code> |
| 174 | * method of <code>DataInput</code>. |
| 175 | * <p> |
| 176 | * Bytes |
| 177 | * for this operation are read from the contained |
| 178 | * input stream. |
| 179 | * |
| 180 | * @param b the buffer into which the data is read. |
| 181 | * @param off the start offset of the data. |
| 182 | * @param len the number of bytes to read. |
| 183 | * @exception EOFException if this input stream reaches the end before |
| 184 | * reading all the bytes. |
| 185 | * @exception IOException the stream has been closed and the contained |
| 186 | * input stream does not support reading after close, or |
| 187 | * another I/O error occurs. |
| 188 | * @see java.io.FilterInputStream#in |
| 189 | */ |
| 190 | public final void readFully(byte b[], int off, int len) throws IOException { |
| 191 | if (len < 0) |
| 192 | throw new IndexOutOfBoundsException(); |
| 193 | int n = 0; |
| 194 | while (n < len) { |
| 195 | int count = in.read(b, off + n, len - n); |
| 196 | if (count < 0) |
| 197 | throw new EOFException(); |
| 198 | n += count; |
| 199 | } |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * See the general contract of the <code>skipBytes</code> |
| 204 | * method of <code>DataInput</code>. |
| 205 | * <p> |
| 206 | * Bytes for this operation are read from the contained |
| 207 | * input stream. |
| 208 | * |
| 209 | * @param n the number of bytes to be skipped. |
| 210 | * @return the actual number of bytes skipped. |
| 211 | * @exception IOException if the contained input stream does not support |
| 212 | * seek, or the stream has been closed and |
| 213 | * the contained input stream does not support |
| 214 | * reading after close, or another I/O error occurs. |
| 215 | */ |
| 216 | public final int skipBytes(int n) throws IOException { |
| 217 | int total = 0; |
| 218 | int cur = 0; |
| 219 | |
| 220 | while ((total<n) && ((cur = (int) in.skip(n-total)) > 0)) { |
| 221 | total += cur; |
| 222 | } |
| 223 | |
| 224 | return total; |
| 225 | } |
| 226 | |
| 227 | /** |
| 228 | * See the general contract of the <code>readBoolean</code> |
| 229 | * method of <code>DataInput</code>. |
| 230 | * <p> |
| 231 | * Bytes for this operation are read from the contained |
| 232 | * input stream. |
| 233 | * |
| 234 | * @return the <code>boolean</code> value read. |
| 235 | * @exception EOFException if this input stream has reached the end. |
| 236 | * @exception IOException the stream has been closed and the contained |
| 237 | * input stream does not support reading after close, or |
| 238 | * another I/O error occurs. |
| 239 | * @see java.io.FilterInputStream#in |
| 240 | */ |
| 241 | public final boolean readBoolean() throws IOException { |
| 242 | int ch = in.read(); |
| 243 | if (ch < 0) |
| 244 | throw new EOFException(); |
| 245 | return (ch != 0); |
| 246 | } |
| 247 | |
| 248 | /** |
| 249 | * See the general contract of the <code>readByte</code> |
| 250 | * method of <code>DataInput</code>. |
| 251 | * <p> |
| 252 | * Bytes |
| 253 | * for this operation are read from the contained |
| 254 | * input stream. |
| 255 | * |
| 256 | * @return the next byte of this input stream as a signed 8-bit |
| 257 | * <code>byte</code>. |
| 258 | * @exception EOFException if this input stream has reached the end. |
| 259 | * @exception IOException the stream has been closed and the contained |
| 260 | * input stream does not support reading after close, or |
| 261 | * another I/O error occurs. |
| 262 | * @see java.io.FilterInputStream#in |
| 263 | */ |
| 264 | public final byte readByte() throws IOException { |
| 265 | int ch = in.read(); |
| 266 | if (ch < 0) |
| 267 | throw new EOFException(); |
| 268 | return (byte)(ch); |
| 269 | } |
| 270 | |
| 271 | /** |
| 272 | * See the general contract of the <code>readUnsignedByte</code> |
| 273 | * method of <code>DataInput</code>. |
| 274 | * <p> |
| 275 | * Bytes |
| 276 | * for this operation are read from the contained |
| 277 | * input stream. |
| 278 | * |
| 279 | * @return the next byte of this input stream, interpreted as an |
| 280 | * unsigned 8-bit number. |
| 281 | * @exception EOFException if this input stream has reached the end. |
| 282 | * @exception IOException the stream has been closed and the contained |
| 283 | * input stream does not support reading after close, or |
| 284 | * another I/O error occurs. |
| 285 | * @see java.io.FilterInputStream#in |
| 286 | */ |
| 287 | public final int readUnsignedByte() throws IOException { |
| 288 | int ch = in.read(); |
| 289 | if (ch < 0) |
| 290 | throw new EOFException(); |
| 291 | return ch; |
| 292 | } |
| 293 | |
| 294 | /** |
| 295 | * See the general contract of the <code>readShort</code> |
| 296 | * method of <code>DataInput</code>. |
| 297 | * <p> |
| 298 | * Bytes |
| 299 | * for this operation are read from the contained |
| 300 | * input stream. |
| 301 | * |
| 302 | * @return the next two bytes of this input stream, interpreted as a |
| 303 | * signed 16-bit number. |
| 304 | * @exception EOFException if this input stream reaches the end before |
| 305 | * reading two bytes. |
| 306 | * @exception IOException the stream has been closed and the contained |
| 307 | * input stream does not support reading after close, or |
| 308 | * another I/O error occurs. |
| 309 | * @see java.io.FilterInputStream#in |
| 310 | */ |
| 311 | public final short readShort() throws IOException { |
| 312 | int ch1 = in.read(); |
| 313 | int ch2 = in.read(); |
| 314 | if ((ch1 | ch2) < 0) |
| 315 | throw new EOFException(); |
| 316 | return (short)((ch1 << 8) + (ch2 << 0)); |
| 317 | } |
| 318 | |
| 319 | /** |
| 320 | * See the general contract of the <code>readUnsignedShort</code> |
| 321 | * method of <code>DataInput</code>. |
| 322 | * <p> |
| 323 | * Bytes |
| 324 | * for this operation are read from the contained |
| 325 | * input stream. |
| 326 | * |
| 327 | * @return the next two bytes of this input stream, interpreted as an |
| 328 | * unsigned 16-bit integer. |
| 329 | * @exception EOFException if this input stream reaches the end before |
| 330 | * reading two bytes. |
| 331 | * @exception IOException the stream has been closed and the contained |
| 332 | * input stream does not support reading after close, or |
| 333 | * another I/O error occurs. |
| 334 | * @see java.io.FilterInputStream#in |
| 335 | */ |
| 336 | public final int readUnsignedShort() throws IOException { |
| 337 | int ch1 = in.read(); |
| 338 | int ch2 = in.read(); |
| 339 | if ((ch1 | ch2) < 0) |
| 340 | throw new EOFException(); |
| 341 | return (ch1 << 8) + (ch2 << 0); |
| 342 | } |
| 343 | |
| 344 | /** |
| 345 | * See the general contract of the <code>readChar</code> |
| 346 | * method of <code>DataInput</code>. |
| 347 | * <p> |
| 348 | * Bytes |
| 349 | * for this operation are read from the contained |
| 350 | * input stream. |
| 351 | * |
| 352 | * @return the next two bytes of this input stream, interpreted as a |
| 353 | * <code>char</code>. |
| 354 | * @exception EOFException if this input stream reaches the end before |
| 355 | * reading two bytes. |
| 356 | * @exception IOException the stream has been closed and the contained |
| 357 | * input stream does not support reading after close, or |
| 358 | * another I/O error occurs. |
| 359 | * @see java.io.FilterInputStream#in |
| 360 | */ |
| 361 | public final char readChar() throws IOException { |
| 362 | int ch1 = in.read(); |
| 363 | int ch2 = in.read(); |
| 364 | if ((ch1 | ch2) < 0) |
| 365 | throw new EOFException(); |
| 366 | return (char)((ch1 << 8) + (ch2 << 0)); |
| 367 | } |
| 368 | |
| 369 | /** |
| 370 | * See the general contract of the <code>readInt</code> |
| 371 | * method of <code>DataInput</code>. |
| 372 | * <p> |
| 373 | * Bytes |
| 374 | * for this operation are read from the contained |
| 375 | * input stream. |
| 376 | * |
| 377 | * @return the next four bytes of this input stream, interpreted as an |
| 378 | * <code>int</code>. |
| 379 | * @exception EOFException if this input stream reaches the end before |
| 380 | * reading four bytes. |
| 381 | * @exception IOException the stream has been closed and the contained |
| 382 | * input stream does not support reading after close, or |
| 383 | * another I/O error occurs. |
| 384 | * @see java.io.FilterInputStream#in |
| 385 | */ |
| 386 | public final int readInt() throws IOException { |
| 387 | int ch1 = in.read(); |
| 388 | int ch2 = in.read(); |
| 389 | int ch3 = in.read(); |
| 390 | int ch4 = in.read(); |
| 391 | if ((ch1 | ch2 | ch3 | ch4) < 0) |
| 392 | throw new EOFException(); |
| 393 | return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0)); |
| 394 | } |
| 395 | |
| 396 | private byte readBuffer[] = new byte[8]; |
| 397 | |
| 398 | /** |
| 399 | * See the general contract of the <code>readLong</code> |
| 400 | * method of <code>DataInput</code>. |
| 401 | * <p> |
| 402 | * Bytes |
| 403 | * for this operation are read from the contained |
| 404 | * input stream. |
| 405 | * |
| 406 | * @return the next eight bytes of this input stream, interpreted as a |
| 407 | * <code>long</code>. |
| 408 | * @exception EOFException if this input stream reaches the end before |
| 409 | * reading eight bytes. |
| 410 | * @exception IOException the stream has been closed and the contained |
| 411 | * input stream does not support reading after close, or |
| 412 | * another I/O error occurs. |
| 413 | * @see java.io.FilterInputStream#in |
| 414 | */ |
| 415 | public final long readLong() throws IOException { |
| 416 | readFully(readBuffer, 0, 8); |
| 417 | return (((long)readBuffer[0] << 56) + |
| 418 | ((long)(readBuffer[1] & 255) << 48) + |
| 419 | ((long)(readBuffer[2] & 255) << 40) + |
| 420 | ((long)(readBuffer[3] & 255) << 32) + |
| 421 | ((long)(readBuffer[4] & 255) << 24) + |
| 422 | ((readBuffer[5] & 255) << 16) + |
| 423 | ((readBuffer[6] & 255) << 8) + |
| 424 | ((readBuffer[7] & 255) << 0)); |
| 425 | } |
| 426 | |
| 427 | /** |
| 428 | * See the general contract of the <code>readFloat</code> |
| 429 | * method of <code>DataInput</code>. |
| 430 | * <p> |
| 431 | * Bytes |
| 432 | * for this operation are read from the contained |
| 433 | * input stream. |
| 434 | * |
| 435 | * @return the next four bytes of this input stream, interpreted as a |
| 436 | * <code>float</code>. |
| 437 | * @exception EOFException if this input stream reaches the end before |
| 438 | * reading four bytes. |
| 439 | * @exception IOException the stream has been closed and the contained |
| 440 | * input stream does not support reading after close, or |
| 441 | * another I/O error occurs. |
| 442 | * @see java.io.DataInputStream#readInt() |
| 443 | * @see java.lang.Float#intBitsToFloat(int) |
| 444 | */ |
| 445 | public final float readFloat() throws IOException { |
| 446 | return Float.intBitsToFloat(readInt()); |
| 447 | } |
| 448 | |
| 449 | /** |
| 450 | * See the general contract of the <code>readDouble</code> |
| 451 | * method of <code>DataInput</code>. |
| 452 | * <p> |
| 453 | * Bytes |
| 454 | * for this operation are read from the contained |
| 455 | * input stream. |
| 456 | * |
| 457 | * @return the next eight bytes of this input stream, interpreted as a |
| 458 | * <code>double</code>. |
| 459 | * @exception EOFException if this input stream reaches the end before |
| 460 | * reading eight bytes. |
| 461 | * @exception IOException the stream has been closed and the contained |
| 462 | * input stream does not support reading after close, or |
| 463 | * another I/O error occurs. |
| 464 | * @see java.io.DataInputStream#readLong() |
| 465 | * @see java.lang.Double#longBitsToDouble(long) |
| 466 | */ |
| 467 | public final double readDouble() throws IOException { |
| 468 | return Double.longBitsToDouble(readLong()); |
| 469 | } |
| 470 | |
| 471 | private char lineBuffer[]; |
| 472 | |
| 473 | /** |
| 474 | * See the general contract of the <code>readLine</code> |
| 475 | * method of <code>DataInput</code>. |
| 476 | * <p> |
| 477 | * Bytes |
| 478 | * for this operation are read from the contained |
| 479 | * input stream. |
| 480 | * |
| 481 | * @deprecated This method does not properly convert bytes to characters. |
| 482 | * As of JDK 1.1, the preferred way to read lines of text is via the |
| 483 | * <code>BufferedReader.readLine()</code> method. Programs that use the |
| 484 | * <code>DataInputStream</code> class to read lines can be converted to use |
| 485 | * the <code>BufferedReader</code> class by replacing code of the form: |
| 486 | * <blockquote><pre> |
| 487 | * DataInputStream d = new DataInputStream(in); |
| 488 | * </pre></blockquote> |
| 489 | * with: |
| 490 | * <blockquote><pre> |
| 491 | * BufferedReader d |
| 492 | * = new BufferedReader(new InputStreamReader(in)); |
| 493 | * </pre></blockquote> |
| 494 | * |
| 495 | * @return the next line of text from this input stream. |
| 496 | * @exception IOException if an I/O error occurs. |
| 497 | * @see java.io.BufferedReader#readLine() |
| 498 | * @see java.io.FilterInputStream#in |
| 499 | */ |
| 500 | @Deprecated |
| 501 | public final String readLine() throws IOException { |
| 502 | char buf[] = lineBuffer; |
| 503 | |
| 504 | if (buf == null) { |
| 505 | buf = lineBuffer = new char[128]; |
| 506 | } |
| 507 | |
| 508 | int room = buf.length; |
| 509 | int offset = 0; |
| 510 | int c; |
| 511 | |
| 512 | loop: while (true) { |
| 513 | switch (c = in.read()) { |
| 514 | case -1: |
| 515 | case '\n': |
| 516 | break loop; |
| 517 | |
| 518 | case '\r': |
| 519 | int c2 = in.read(); |
| 520 | if ((c2 != '\n') && (c2 != -1)) { |
| 521 | if (!(in instanceof PushbackInputStream)) { |
| 522 | this.in = new PushbackInputStream(in); |
| 523 | } |
| 524 | ((PushbackInputStream)in).unread(c2); |
| 525 | } |
| 526 | break loop; |
| 527 | |
| 528 | default: |
| 529 | if (--room < 0) { |
| 530 | buf = new char[offset + 128]; |
| 531 | room = buf.length - offset - 1; |
| 532 | System.arraycopy(lineBuffer, 0, buf, 0, offset); |
| 533 | lineBuffer = buf; |
| 534 | } |
| 535 | buf[offset++] = (char) c; |
| 536 | break; |
| 537 | } |
| 538 | } |
| 539 | if ((c == -1) && (offset == 0)) { |
| 540 | return null; |
| 541 | } |
| 542 | return String.copyValueOf(buf, 0, offset); |
| 543 | } |
| 544 | |
| 545 | /** |
| 546 | * See the general contract of the <code>readUTF</code> |
| 547 | * method of <code>DataInput</code>. |
| 548 | * <p> |
| 549 | * Bytes |
| 550 | * for this operation are read from the contained |
| 551 | * input stream. |
| 552 | * |
| 553 | * @return a Unicode string. |
| 554 | * @exception EOFException if this input stream reaches the end before |
| 555 | * reading all the bytes. |
| 556 | * @exception IOException the stream has been closed and the contained |
| 557 | * input stream does not support reading after close, or |
| 558 | * another I/O error occurs. |
| 559 | * @exception UTFDataFormatException if the bytes do not represent a valid |
| 560 | * modified UTF-8 encoding of a string. |
| 561 | * @see java.io.DataInputStream#readUTF(java.io.DataInput) |
| 562 | */ |
| 563 | public final String readUTF() throws IOException { |
| 564 | return readUTF(this); |
| 565 | } |
| 566 | |
| 567 | /** |
| 568 | * Reads from the |
| 569 | * stream <code>in</code> a representation |
| 570 | * of a Unicode character string encoded in |
| 571 | * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format; |
| 572 | * this string of characters is then returned as a <code>String</code>. |
| 573 | * The details of the modified UTF-8 representation |
| 574 | * are exactly the same as for the <code>readUTF</code> |
| 575 | * method of <code>DataInput</code>. |
| 576 | * |
| 577 | * @param in a data input stream. |
| 578 | * @return a Unicode string. |
| 579 | * @exception EOFException if the input stream reaches the end |
| 580 | * before all the bytes. |
| 581 | * @exception IOException the stream has been closed and the contained |
| 582 | * input stream does not support reading after close, or |
| 583 | * another I/O error occurs. |
| 584 | * @exception UTFDataFormatException if the bytes do not represent a |
| 585 | * valid modified UTF-8 encoding of a Unicode string. |
| 586 | * @see java.io.DataInputStream#readUnsignedShort() |
| 587 | */ |
| 588 | public final static String readUTF(DataInput in) throws IOException { |
| 589 | int utflen = in.readUnsignedShort(); |
| 590 | byte[] bytearr = null; |
| 591 | char[] chararr = null; |
| 592 | if (in instanceof DataInputStream) { |
| 593 | DataInputStream dis = (DataInputStream)in; |
| 594 | if (dis.bytearr.length < utflen){ |
| 595 | dis.bytearr = new byte[utflen*2]; |
| 596 | dis.chararr = new char[utflen*2]; |
| 597 | } |
| 598 | chararr = dis.chararr; |
| 599 | bytearr = dis.bytearr; |
| 600 | } else { |
| 601 | bytearr = new byte[utflen]; |
| 602 | chararr = new char[utflen]; |
| 603 | } |
| 604 | |
| 605 | int c, char2, char3; |
| 606 | int count = 0; |
| 607 | int chararr_count=0; |
| 608 | |
| 609 | in.readFully(bytearr, 0, utflen); |
| 610 | |
| 611 | while (count < utflen) { |
| 612 | c = (int) bytearr[count] & 0xff; |
| 613 | if (c > 127) break; |
| 614 | count++; |
| 615 | chararr[chararr_count++]=(char)c; |
| 616 | } |
| 617 | |
| 618 | while (count < utflen) { |
| 619 | c = (int) bytearr[count] & 0xff; |
| 620 | switch (c >> 4) { |
| 621 | case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: |
| 622 | /* 0xxxxxxx*/ |
| 623 | count++; |
| 624 | chararr[chararr_count++]=(char)c; |
| 625 | break; |
| 626 | case 12: case 13: |
| 627 | /* 110x xxxx 10xx xxxx*/ |
| 628 | count += 2; |
| 629 | if (count > utflen) |
| 630 | throw new UTFDataFormatException( |
| 631 | "malformed input: partial character at end"); |
| 632 | char2 = (int) bytearr[count-1]; |
| 633 | if ((char2 & 0xC0) != 0x80) |
| 634 | throw new UTFDataFormatException( |
| 635 | "malformed input around byte " + count); |
| 636 | chararr[chararr_count++]=(char)(((c & 0x1F) << 6) | |
| 637 | (char2 & 0x3F)); |
| 638 | break; |
| 639 | case 14: |
| 640 | /* 1110 xxxx 10xx xxxx 10xx xxxx */ |
| 641 | count += 3; |
| 642 | if (count > utflen) |
| 643 | throw new UTFDataFormatException( |
| 644 | "malformed input: partial character at end"); |
| 645 | char2 = (int) bytearr[count-2]; |
| 646 | char3 = (int) bytearr[count-1]; |
| 647 | if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80)) |
| 648 | throw new UTFDataFormatException( |
| 649 | "malformed input around byte " + (count-1)); |
| 650 | chararr[chararr_count++]=(char)(((c & 0x0F) << 12) | |
| 651 | ((char2 & 0x3F) << 6) | |
| 652 | ((char3 & 0x3F) << 0)); |
| 653 | break; |
| 654 | default: |
| 655 | /* 10xx xxxx, 1111 xxxx */ |
| 656 | throw new UTFDataFormatException( |
| 657 | "malformed input around byte " + count); |
| 658 | } |
| 659 | } |
| 660 | // The number of chars produced may be less than utflen |
| 661 | return new String(chararr, 0, chararr_count); |
| 662 | } |
| 663 | } |