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1: /* DataInputStream.java -- FilteredInputStream that implements DataInput 2: Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005 Free Software Foundation 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: package java.io; 39: 40: /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 41: * "The Java Language Specification", ISBN 0-201-63451-1 42: * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. 43: * Status: Believed complete and correct. 44: */ 45: 46: /** 47: * This subclass of <code>FilteredInputStream</code> implements the 48: * <code>DataInput</code> interface that provides method for reading primitive 49: * Java data types from a stream. 50: * 51: * @see DataInput 52: * 53: * @author Warren Levy (warrenl@cygnus.com) 54: * @author Aaron M. Renn (arenn@urbanophile.com) 55: * @date October 20, 1998. 56: */ 57: public class DataInputStream extends FilterInputStream implements DataInput 58: { 59: // Byte buffer, used to make primitive read calls more efficient. 60: byte[] buf = new byte [8]; 61: 62: /** 63: * This constructor initializes a new <code>DataInputStream</code> 64: * to read from the specified subordinate stream. 65: * 66: * @param in The subordinate <code>InputStream</code> to read from 67: */ 68: public DataInputStream (InputStream in) 69: { 70: super (in); 71: } 72: 73: /** 74: * This method reads bytes from the underlying stream into the specified 75: * byte array buffer. It will attempt to fill the buffer completely, but 76: * may return a short count if there is insufficient data remaining to be 77: * read to fill the buffer. 78: * 79: * @param b The buffer into which bytes will be read. 80: * 81: * @return The actual number of bytes read, or -1 if end of stream reached 82: * before reading any bytes. 83: * 84: * @exception IOException If an error occurs. 85: */ 86: public final int read (byte[] b) throws IOException 87: { 88: return in.read (b, 0, b.length); 89: } 90: 91: /** 92: * This method reads bytes from the underlying stream into the specified 93: * byte array buffer. It will attempt to read <code>len</code> bytes and 94: * will start storing them at position <code>off</code> into the buffer. 95: * This method can return a short count if there is insufficient data 96: * remaining to be read to complete the desired read length. 97: * 98: * @param b The buffer into which bytes will be read. 99: * @param off The offset into the buffer to start storing bytes. 100: * @param len The requested number of bytes to read. 101: * 102: * @return The actual number of bytes read, or -1 if end of stream reached 103: * before reading any bytes. 104: * 105: * @exception IOException If an error occurs. 106: */ 107: public final int read (byte[] b, int off, int len) throws IOException 108: { 109: return in.read (b, off, len); 110: } 111: 112: /** 113: * This method reads a Java boolean value from an input stream. It does 114: * so by reading a single byte of data. If that byte is zero, then the 115: * value returned is <code>false</code>. If the byte is non-zero, then 116: * the value returned is <code>true</code>. 117: * <p> 118: * This method can read a <code>boolean</code> written by an object 119: * implementing the <code>writeBoolean()</code> method in the 120: * <code>DataOutput</code> interface. 121: * 122: * @return The <code>boolean</code> value read 123: * 124: * @exception EOFException If end of file is reached before reading 125: * the boolean 126: * @exception IOException If any other error occurs 127: * 128: * @see DataOutput#writeBoolean 129: */ 130: public final boolean readBoolean () throws IOException 131: { 132: return convertToBoolean (in.read ()); 133: } 134: 135: /** 136: * This method reads a Java byte value from an input stream. The value 137: * is in the range of -128 to 127. 138: * <p> 139: * This method can read a <code>byte</code> written by an object 140: * implementing the <code>writeByte()</code> method in the 141: * <code>DataOutput</code> interface. 142: * 143: * @return The <code>byte</code> value read 144: * 145: * @exception EOFException If end of file is reached before reading the byte 146: * @exception IOException If any other error occurs 147: * 148: * @see DataOutput#writeByte 149: */ 150: public final byte readByte () throws IOException 151: { 152: return convertToByte (in.read ()); 153: } 154: 155: /** 156: * This method reads a Java <code>char</code> value from an input stream. 157: * It operates by reading two bytes from the stream and converting them to 158: * a single 16-bit Java <code>char</code>. The two bytes are stored most 159: * significant byte first (i.e., "big endian") regardless of the native 160: * host byte ordering. 161: * <p> 162: * As an example, if <code>byte1</code> and <code>byte2</code> 163: * represent the first and second byte read from the stream 164: * respectively, they will be transformed to a <code>char</code> in 165: * the following manner: 166: * <p> 167: * <code>(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code> 168: * <p> 169: * This method can read a <code>char</code> written by an object 170: * implementing the <code>writeChar()</code> method in the 171: * <code>DataOutput</code> interface. 172: * 173: * @return The <code>char</code> value read 174: * 175: * @exception EOFException If end of file is reached before reading the char 176: * @exception IOException If any other error occurs 177: * 178: * @see DataOutput#writeChar 179: */ 180: public final char readChar () throws IOException 181: { 182: readFully (buf, 0, 2); 183: return convertToChar (buf); 184: } 185: 186: /** 187: * This method reads a Java double value from an input stream. It operates 188: * by first reading a <code>long</code> value from the stream by calling the 189: * <code>readLong()</code> method in this interface, then converts 190: * that <code>long</code> to a <code>double</code> using the 191: * <code>longBitsToDouble</code> method in the class 192: * <code>java.lang.Double</code> 193: * <p> 194: * This method can read a <code>double</code> written by an object 195: * implementing the <code>writeDouble()</code> method in the 196: * <code>DataOutput</code> interface. 197: * 198: * @return The <code>double</code> value read 199: * 200: * @exception EOFException If end of file is reached before reading 201: * the double 202: * @exception IOException If any other error occurs 203: * 204: * @see DataOutput#writeDouble 205: * @see java.lang.Double#longBitsToDouble 206: */ 207: public final double readDouble () throws IOException 208: { 209: return Double.longBitsToDouble (readLong ()); 210: } 211: 212: /** 213: * This method reads a Java float value from an input stream. It 214: * operates by first reading an <code>int</code> value from the 215: * stream by calling the <code>readInt()</code> method in this 216: * interface, then converts that <code>int</code> to a 217: * <code>float</code> using the <code>intBitsToFloat</code> method 218: * in the class <code>java.lang.Float</code> 219: * <p> 220: * This method can read a <code>float</code> written by an object 221: * implementing the <code>writeFloat()</code> method in the 222: * <code>DataOutput</code> interface. 223: * 224: * @return The <code>float</code> value read 225: * 226: * @exception EOFException If end of file is reached before reading the float 227: * @exception IOException If any other error occurs 228: * 229: * @see DataOutput#writeFloat 230: * @see java.lang.Float#intBitsToFloat 231: */ 232: public final float readFloat () throws IOException 233: { 234: return Float.intBitsToFloat (readInt ()); 235: } 236: 237: /** 238: * This method reads raw bytes into the passed array until the array is 239: * full. Note that this method blocks until the data is available and 240: * throws an exception if there is not enough data left in the stream to 241: * fill the buffer. Note also that zero length buffers are permitted. 242: * In this case, the method will return immediately without reading any 243: * bytes from the stream. 244: * 245: * @param b The buffer into which to read the data 246: * 247: * @exception EOFException If end of file is reached before filling the 248: * buffer 249: * @exception IOException If any other error occurs 250: */ 251: public final void readFully (byte[] b) throws IOException 252: { 253: readFully (b, 0, b.length); 254: } 255: 256: /** 257: * This method reads raw bytes into the passed array <code>buf</code> 258: * starting 259: * <code>offset</code> bytes into the buffer. The number of bytes read 260: * will be 261: * exactly <code>len</code>. Note that this method blocks until the data is 262: * available and throws an exception if there is not enough data left in 263: * the stream to read <code>len</code> bytes. Note also that zero length 264: * buffers are permitted. In this case, the method will return immediately 265: * without reading any bytes from the stream. 266: * 267: * @param buf The buffer into which to read the data 268: * @param offset The offset into the buffer to start storing data 269: * @param len The number of bytes to read into the buffer 270: * 271: * @exception EOFException If end of file is reached before filling the 272: * buffer 273: * @exception IOException If any other error occurs 274: */ 275: public final void readFully (byte[] buf, int offset, int len) throws IOException 276: { 277: if (len < 0) 278: throw new IndexOutOfBoundsException("Negative length: " + len); 279: 280: while (len > 0) 281: { 282: // in.read will block until some data is available. 283: int numread = in.read (buf, offset, len); 284: if (numread < 0) 285: throw new EOFException (); 286: len -= numread; 287: offset += numread; 288: } 289: } 290: 291: /** 292: * This method reads a Java <code>int</code> value from an input stream 293: * It operates by reading four bytes from the stream and converting them to 294: * a single Java <code>int</code>. The bytes are stored most 295: * significant byte first (i.e., "big endian") regardless of the native 296: * host byte ordering. 297: * <p> 298: * As an example, if <code>byte1</code> through <code>byte4</code> represent 299: * the first four bytes read from the stream, they will be 300: * transformed to an <code>int</code> in the following manner: 301: * <p> 302: * <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) + 303: * ((byte3 & 0xFF)<< 8) + (byte4 & 0xFF)))</code> 304: * <p> 305: * The value returned is in the range of -2147483648 to 2147483647. 306: * <p> 307: * This method can read an <code>int</code> written by an object 308: * implementing the <code>writeInt()</code> method in the 309: * <code>DataOutput</code> interface. 310: * 311: * @return The <code>int</code> value read 312: * 313: * @exception EOFException If end of file is reached before reading the int 314: * @exception IOException If any other error occurs 315: * 316: * @see DataOutput#writeInt 317: */ 318: public final int readInt () throws IOException 319: { 320: readFully (buf, 0, 4); 321: return convertToInt (buf); 322: } 323: 324: /** 325: * This method reads the next line of text data from an input 326: * stream. It operates by reading bytes and converting those bytes 327: * to <code>char</code> values by treating the byte read as the low 328: * eight bits of the <code>char</code> and using 0 as the high eight 329: * bits. Because of this, it does not support the full 16-bit 330: * Unicode character set. 331: * <p> 332: * The reading of bytes ends when either the end of file or a line 333: * terminator is encountered. The bytes read are then returned as a 334: * <code>String</code> A line terminator is a byte sequence 335: * consisting of either <code>\r</code>, <code>\n</code> or 336: * <code>\r\n</code>. These termination charaters are discarded and 337: * are not returned as part of the string. 338: * <p> 339: * This method can read data that was written by an object implementing the 340: * <code>writeLine()</code> method in <code>DataOutput</code>. 341: * 342: * @return The line read as a <code>String</code> 343: * 344: * @exception IOException If an error occurs 345: * 346: * @see DataOutput 347: * 348: * @deprecated 349: */ 350: public final String readLine() throws IOException 351: { 352: StringBuffer strb = new StringBuffer(); 353: 354: while (true) 355: { 356: int c = in.read(); 357: if (c == -1) // got an EOF 358: return strb.length() > 0 ? strb.toString() : null; 359: if (c == '\r') 360: { 361: int next_c = in.read(); 362: if (next_c != '\n' && next_c != -1) 363: { 364: if (!(in instanceof PushbackInputStream)) 365: in = new PushbackInputStream(in); 366: ((PushbackInputStream) in).unread(next_c); 367: } 368: break; 369: } 370: if (c == '\n') 371: break; 372: strb.append((char) c); 373: } 374: 375: return strb.length() > 0 ? strb.toString() : ""; 376: } 377: 378: /** 379: * This method reads a Java <code>long</code> value from an input stream 380: * It operates by reading eight bytes from the stream and converting them to 381: * a single Java <code>long</code>. The bytes are stored most 382: * significant byte first (i.e., "big endian") regardless of the native 383: * host byte ordering. 384: * <p> 385: * As an example, if <code>byte1</code> through <code>byte8</code> represent 386: * the first eight bytes read from the stream, they will be 387: * transformed to an <code>long</code> in the following manner: 388: * <p> 389: * <code>(long)(((byte1 & 0xFF) << 56) + ((byte2 & 0xFF) << 48) + 390: * ((byte3 & 0xFF) << 40) + ((byte4 & 0xFF) << 32) + 391: * ((byte5 & 0xFF) << 24) + ((byte6 & 0xFF) << 16) + 392: * ((byte7 & 0xFF) << 8) + (byte8 & 0xFF))) 393: * </code> 394: * <p> 395: * The value returned is in the range of -9223372036854775808 to 396: * 9223372036854775807. 397: * <p> 398: * This method can read an <code>long</code> written by an object 399: * implementing the <code>writeLong()</code> method in the 400: * <code>DataOutput</code> interface. 401: * 402: * @return The <code>long</code> value read 403: * 404: * @exception EOFException If end of file is reached before reading the long 405: * @exception IOException If any other error occurs 406: * 407: * @see DataOutput#writeLong 408: */ 409: public final long readLong () throws IOException 410: { 411: readFully (buf, 0, 8); 412: return convertToLong (buf); 413: } 414: 415: /** 416: * This method reads a signed 16-bit value into a Java in from the 417: * stream. It operates by reading two bytes from the stream and 418: * converting them to a single 16-bit Java <code>short</code>. The 419: * two bytes are stored most significant byte first (i.e., "big 420: * endian") regardless of the native host byte ordering. 421: * <p> 422: * As an example, if <code>byte1</code> and <code>byte2</code> 423: * represent the first and second byte read from the stream 424: * respectively, they will be transformed to a <code>short</code>. in 425: * the following manner: 426: * <p> 427: * <code>(short)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF))</code> 428: * <p> 429: * The value returned is in the range of -32768 to 32767. 430: * <p> 431: * This method can read a <code>short</code> written by an object 432: * implementing the <code>writeShort()</code> method in the 433: * <code>DataOutput</code> interface. 434: * 435: * @return The <code>short</code> value read 436: * 437: * @exception EOFException If end of file is reached before reading the value 438: * @exception IOException If any other error occurs 439: * 440: * @see DataOutput#writeShort 441: */ 442: public final short readShort () throws IOException 443: { 444: readFully (buf, 0, 2); 445: return convertToShort (buf); 446: } 447: 448: /** 449: * This method reads 8 unsigned bits into a Java <code>int</code> 450: * value from the stream. The value returned is in the range of 0 to 451: * 255. 452: * <p> 453: * This method can read an unsigned byte written by an object 454: * implementing the <code>writeUnsignedByte()</code> method in the 455: * <code>DataOutput</code> interface. 456: * 457: * @return The unsigned bytes value read as a Java <code>int</code>. 458: * 459: * @exception EOFException If end of file is reached before reading the value 460: * @exception IOException If any other error occurs 461: * 462: * @see DataOutput#writeByte 463: */ 464: public final int readUnsignedByte () throws IOException 465: { 466: return convertToUnsignedByte (in.read ()); 467: } 468: 469: /** 470: * This method reads 16 unsigned bits into a Java int value from the stream. 471: * It operates by reading two bytes from the stream and converting them to 472: * a single Java <code>int</code> The two bytes are stored most 473: * significant byte first (i.e., "big endian") regardless of the native 474: * host byte ordering. 475: * <p> 476: * As an example, if <code>byte1</code> and <code>byte2</code> 477: * represent the first and second byte read from the stream 478: * respectively, they will be transformed to an <code>int</code> in 479: * the following manner: 480: * <p> 481: * <code>(int)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))</code> 482: * <p> 483: * The value returned is in the range of 0 to 65535. 484: * <p> 485: * This method can read an unsigned short written by an object 486: * implementing the <code>writeUnsignedShort()</code> method in the 487: * <code>DataOutput</code> interface. 488: * 489: * @return The unsigned short value read as a Java <code>int</code> 490: * 491: * @exception EOFException If end of file is reached before reading the value 492: * @exception IOException If any other error occurs 493: * 494: * @see DataOutput#writeShort 495: */ 496: public final int readUnsignedShort () throws IOException 497: { 498: readFully (buf, 0, 2); 499: return convertToUnsignedShort (buf); 500: } 501: 502: /** 503: * This method reads a <code>String</code> from an input stream that 504: * is encoded in a modified UTF-8 format. This format has a leading 505: * two byte sequence that contains the remaining number of bytes to 506: * read. This two byte sequence is read using the 507: * <code>readUnsignedShort()</code> method of this interface. 508: * <p> 509: * After the number of remaining bytes have been determined, these 510: * bytes are read an transformed into <code>char</code> values. 511: * These <code>char</code> values are encoded in the stream using 512: * either a one, two, or three byte format. The particular format 513: * in use can be determined by examining the first byte read. 514: * <p> 515: * If the first byte has a high order bit of 0, then that character 516: * consists on only one byte. This character value consists of 517: * seven bits that are at positions 0 through 6 of the byte. As an 518: * example, if <code>byte1</code> is the byte read from the stream, 519: * it would be converted to a <code>char</code> like so: 520: * <p> 521: * <code>(char)byte1</code> 522: * <p> 523: * If the first byte has 110 as its high order bits, then the 524: * character consists of two bytes. The bits that make up the character 525: * value are in positions 0 through 4 of the first byte and bit positions 526: * 0 through 5 of the second byte. (The second byte should have 527: * 10 as its high order bits). These values are in most significant 528: * byte first (i.e., "big endian") order. 529: * <p> 530: * As an example, if <code>byte1</code> and <code>byte2</code> are 531: * the first two bytes read respectively, and the high order bits of 532: * them match the patterns which indicate a two byte character 533: * encoding, then they would be converted to a Java 534: * <code>char</code> like so: 535: * <p> 536: * <code>(char)(((byte1 & 0x1F) << 6) | (byte2 & 0x3F))</code> 537: * <p> 538: * If the first byte has a 1110 as its high order bits, then the 539: * character consists of three bytes. The bits that make up the character 540: * value are in positions 0 through 3 of the first byte and bit positions 541: * 0 through 5 of the other two bytes. (The second and third bytes should 542: * have 10 as their high order bits). These values are in most 543: * significant byte first (i.e., "big endian") order. 544: * <p> 545: * As an example, if <code>byte1</code> <code>byte2</code> and 546: * <code>byte3</code> are the three bytes read, and the high order 547: * bits of them match the patterns which indicate a three byte 548: * character encoding, then they would be converted to a Java 549: * <code>char</code> like so: 550: * <p> 551: * <code>(char)(((byte1 & 0x0F) << 12) | ((byte2 & 0x3F) << 6) | 552: * (byte3 & 0x3F))</code> 553: * <p> 554: * Note that all characters are encoded in the method that requires 555: * the fewest number of bytes with the exception of the character 556: * with the value of <code>\u0000</code> which is encoded as two 557: * bytes. This is a modification of the UTF standard used to 558: * prevent C language style <code>NUL</code> values from appearing 559: * in the byte stream. 560: * <p> 561: * This method can read data that was written by an object implementing the 562: * <code>writeUTF()</code> method in <code>DataOutput</code> 563: * 564: * @return The <code>String</code> read 565: * 566: * @exception EOFException If end of file is reached before reading 567: * the String 568: * @exception UTFDataFormatException If the data is not in UTF-8 format 569: * @exception IOException If any other error occurs 570: * 571: * @see DataOutput#writeUTF 572: */ 573: public final String readUTF () throws IOException 574: { 575: return readUTF (this); 576: } 577: 578: /** 579: * This method reads a String encoded in UTF-8 format from the 580: * specified <code>DataInput</code> source. 581: * 582: * @param in The <code>DataInput</code> source to read from 583: * 584: * @return The String read from the source 585: * 586: * @exception IOException If an error occurs 587: * 588: * @see DataInput#readUTF 589: */ 590: public static final String readUTF(DataInput in) throws IOException 591: { 592: final int UTFlen = in.readUnsignedShort (); 593: byte[] buf = new byte [UTFlen]; 594: 595: // This blocks until the entire string is available rather than 596: // doing partial processing on the bytes that are available and then 597: // blocking. An advantage of the latter is that Exceptions 598: // could be thrown earlier. The former is a bit cleaner. 599: in.readFully (buf, 0, UTFlen); 600: 601: return convertFromUTF (buf); 602: } 603: 604: /** 605: * This method attempts to skip and discard the specified number of bytes 606: * in the input stream. It may actually skip fewer bytes than requested. 607: * This method will not skip any bytes if passed a negative number of bytes 608: * to skip. 609: * 610: * @param n The requested number of bytes to skip. 611: * 612: * @return The requested number of bytes to skip. 613: * 614: * @exception IOException If an error occurs. 615: * @specnote The JDK docs claim that this returns the number of bytes 616: * actually skipped. The JCL claims that this method can throw an 617: * EOFException. Neither of these appear to be true in the JDK 1.3's 618: * implementation. This tries to implement the actual JDK behaviour. 619: */ 620: public final int skipBytes (int n) throws IOException 621: { 622: if (n <= 0) 623: return 0; 624: try 625: { 626: return (int) in.skip (n); 627: } 628: catch (EOFException x) 629: { 630: // do nothing. 631: } 632: return n; 633: } 634: 635: static boolean convertToBoolean (int b) throws EOFException 636: { 637: if (b < 0) 638: throw new EOFException (); 639: 640: return (b != 0); 641: } 642: 643: static byte convertToByte (int i) throws EOFException 644: { 645: if (i < 0) 646: throw new EOFException (); 647: 648: return (byte) i; 649: } 650: 651: static int convertToUnsignedByte (int i) throws EOFException 652: { 653: if (i < 0) 654: throw new EOFException (); 655: 656: return (i & 0xFF); 657: } 658: 659: static char convertToChar (byte[] buf) 660: { 661: return (char) ((buf [0] << 8) 662: | (buf [1] & 0xff)); 663: } 664: 665: static short convertToShort (byte[] buf) 666: { 667: return (short) ((buf [0] << 8) 668: | (buf [1] & 0xff)); 669: } 670: 671: static int convertToUnsignedShort (byte[] buf) 672: { 673: return (((buf [0] & 0xff) << 8) 674: | (buf [1] & 0xff)); 675: } 676: 677: static int convertToInt (byte[] buf) 678: { 679: return (((buf [0] & 0xff) << 24) 680: | ((buf [1] & 0xff) << 16) 681: | ((buf [2] & 0xff) << 8) 682: | (buf [3] & 0xff)); 683: } 684: 685: static long convertToLong (byte[] buf) 686: { 687: return (((long)(buf [0] & 0xff) << 56) | 688: ((long)(buf [1] & 0xff) << 48) | 689: ((long)(buf [2] & 0xff) << 40) | 690: ((long)(buf [3] & 0xff) << 32) | 691: ((long)(buf [4] & 0xff) << 24) | 692: ((long)(buf [5] & 0xff) << 16) | 693: ((long)(buf [6] & 0xff) << 8) | 694: ((long)(buf [7] & 0xff))); 695: } 696: 697: // FIXME: This method should be re-thought. I suspect we have multiple 698: // UTF-8 decoders floating around. We should use the standard charset 699: // converters, maybe and adding a direct call into one of the new 700: // NIO converters for a super-fast UTF8 decode. 701: static String convertFromUTF (byte[] buf) 702: throws EOFException, UTFDataFormatException 703: { 704: // Give StringBuffer an initial estimated size to avoid 705: // enlarge buffer frequently 706: StringBuffer strbuf = new StringBuffer (buf.length / 2 + 2); 707: 708: for (int i = 0; i < buf.length; ) 709: { 710: if ((buf [i] & 0x80) == 0) // bit pattern 0xxxxxxx 711: strbuf.append ((char) (buf [i++] & 0xFF)); 712: else if ((buf [i] & 0xE0) == 0xC0) // bit pattern 110xxxxx 713: { 714: if (i + 1 >= buf.length 715: || (buf [i + 1] & 0xC0) != 0x80) 716: throw new UTFDataFormatException (); 717: 718: strbuf.append((char) (((buf [i++] & 0x1F) << 6) 719: | (buf [i++] & 0x3F))); 720: } 721: else if ((buf [i] & 0xF0) == 0xE0) // bit pattern 1110xxxx 722: { 723: if (i + 2 >= buf.length 724: || (buf [i + 1] & 0xC0) != 0x80 725: || (buf [i + 2] & 0xC0) != 0x80) 726: throw new UTFDataFormatException (); 727: 728: strbuf.append ((char) (((buf [i++] & 0x0F) << 12) 729: | ((buf [i++] & 0x3F) << 6) 730: | (buf [i++] & 0x3F))); 731: } 732: else // must be ((buf [i] & 0xF0) == 0xF0 || (buf [i] & 0xC0) == 0x80) 733: throw new UTFDataFormatException (); // bit patterns 1111xxxx or 734: // 10xxxxxx 735: } 736: 737: return strbuf.toString (); 738: } 739: }
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