2362N/A * Copyright (c) 1995, 2006, Oracle and/or its affiliates. All rights reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 2362N/A * published by the Free Software Foundation. Oracle designates this 0N/A * particular file as subject to the "Classpath" exception as provided 2362N/A * by Oracle in the LICENSE file that accompanied this code. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 0N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2362N/A * or visit www.oracle.com if you need additional information or have any 0N/A * The <code>DataInput</code> interface provides 0N/A * for reading bytes from a binary stream and 0N/A * reconstructing from them data in any of 0N/A * the Java primitive types. There is also 0N/A * facility for reconstructing a <code>String</code> 0N/A * <a href="#modified-utf-8">modified UTF-8</a> 0N/A * It is generally true of all the reading 0N/A * routines in this interface that if end of 0N/A * file is reached before the desired number 0N/A * of bytes has been read, an <code>EOFException</code> 0N/A * (which is a kind of <code>IOException</code>) 0N/A * is thrown. If any byte cannot be read for 0N/A * any reason other than end of file, an <code>IOException</code> 0N/A * other than <code>EOFException</code> is 0N/A * thrown. In particular, an <code>IOException</code> 0N/A * may be thrown if the input stream has been 0N/A * <h4><a name="modified-utf-8">Modified UTF-8</a></h4> 0N/A * Implementations of the DataInput and DataOutput interfaces represent 0N/A * Unicode strings in a format that is a slight modification of UTF-8. 0N/A * (For information regarding the standard UTF-8 format, see section 0N/A * <i>3.9 Unicode Encoding Forms</i> of <i>The Unicode Standard, Version 0N/A * Note that in the following tables, the most significant bit appears in the 0N/A * far left-hand column. 0N/A * All characters in the range <code>'\u0001'</code> to 0N/A * <code>'\u007F'</code> are represented by a single byte: 0N/A * <table border="1" cellspacing="0" cellpadding="8" width="50%" 0N/A * summary="Bit values and bytes"> 0N/A * <th id="bit">Bit Values</th> 0N/A * <th id="byte1">Byte 1</th> 0N/A * <table border="1" cellspacing="0" width="100%"> 0N/A * <td width="12%"><center>0</center> 0N/A * <td colspan="7"><center>bits 6-0</center> 0N/A * The null character <code>'\u0000'</code> and characters in the 0N/A * range <code>'\u0080'</code> to <code>'\u07FF'</code> are 0N/A * represented by a pair of bytes: 0N/A * <table border="1" cellspacing="0" cellpadding="8" width="50%" 0N/A * summary="Bit values and bytes"> 0N/A * <th id="bit">Bit Values</th> 0N/A * <th id="byte1">Byte 1</th> 0N/A * <table border="1" cellspacing="0" width="100%"> 0N/A * <td width="12%"><center>1</center> 0N/A * <td width="13%"><center>1</center> 0N/A * <td width="12%"><center>0</center> 0N/A * <td colspan="5"><center>bits 10-6</center> 0N/A * <th id="byte2">Byte 2</th> 0N/A * <table border="1" cellspacing="0" width="100%"> 0N/A * <td width="12%"><center>1</center> 0N/A * <td width="13%"><center>0</center> 0N/A * <td colspan="6"><center>bits 5-0</center> 0N/A * <code>char</code> values in the range <code>'\u0800'</code> to 0N/A * <code>'\uFFFF'</code> are represented by three bytes: 0N/A * <table border="1" cellspacing="0" cellpadding="8" width="50%" 0N/A * summary="Bit values and bytes"> 0N/A * <th id="bit">Bit Values</th> 0N/A * <th id="byte1">Byte 1</th> 0N/A * <table border="1" cellspacing="0" width="100%"> 0N/A * <td width="12%"><center>1</center> 0N/A * <td width="13%"><center>1</center> 0N/A * <td width="12%"><center>1</center> 0N/A * <td width="13%"><center>0</center> 0N/A * <td colspan="4"><center>bits 15-12</center> 0N/A * <th id="byte2">Byte 2</th> 0N/A * <table border="1" cellspacing="0" width="100%"> 0N/A * <td width="12%"><center>1</center> 0N/A * <td width="13%"><center>0</center> 0N/A * <td colspan="6"><center>bits 11-6</center> 0N/A * <th id="byte3">Byte 3</th> 0N/A * <table border="1" cellspacing="0" width="100%"> 0N/A * <td width="12%"><center>1</center> 0N/A * <td width="13%"><center>0</center> 0N/A * <td colspan="6"><center>bits 5-0</center> 0N/A * The differences between this format and the 0N/A * standard UTF-8 format are the following: 0N/A * <li>The null byte <code>'\u0000'</code> is encoded in 2-byte format 0N/A * rather than 1-byte, so that the encoded strings never have 0N/A * <li>Only the 1-byte, 2-byte, and 3-byte formats are used. 0N/A * are represented in the form of surrogate pairs. 0N/A * @author Frank Yellin 0N/A * @see java.io.DataInputStream 0N/A * @see java.io.DataOutput 0N/A * Reads some bytes from an input 0N/A * stream and stores them into the buffer 0N/A * array <code>b</code>. The number of bytes 0N/A * to the length of <code>b</code>. 0N/A * This method blocks until one of the 0N/A * following conditions occurs:<p> 0N/A * <li><code>b.length</code> 0N/A * bytes of input data are available, in which 0N/A * case a normal return is made. 0N/A * file is detected, in which case an <code>EOFException</code> 0N/A * <li>An I/O error occurs, in 0N/A * which case an <code>IOException</code> other 0N/A * than <code>EOFException</code> is thrown. 0N/A * If <code>b</code> is <code>null</code>, 0N/A * a <code>NullPointerException</code> is thrown. 0N/A * If <code>b.length</code> is zero, then 0N/A * no bytes are read. Otherwise, the first 0N/A * byte read is stored into element <code>b[0]</code>, 0N/A * the next one into <code>b[1]</code>, and 0N/A * If an exception is thrown from 0N/A * this method, then it may be that some but 0N/A * not all bytes of <code>b</code> have been 0N/A * updated with data from the input stream. 0N/A * @param b the buffer into which the data is read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads <code>len</code> 0N/A * blocks until one of the following conditions 0N/A * <li><code>len</code> bytes 0N/A * of input data are available, in which case 0N/A * a normal return is made. 0N/A * is detected, in which case an <code>EOFException</code> 0N/A * <li>An I/O error occurs, in 0N/A * which case an <code>IOException</code> other 0N/A * than <code>EOFException</code> is thrown. 0N/A * If <code>b</code> is <code>null</code>, 0N/A * a <code>NullPointerException</code> is thrown. 0N/A * If <code>off</code> is negative, or <code>len</code> 0N/A * is negative, or <code>off+len</code> is 0N/A * greater than the length of the array <code>b</code>, 0N/A * then an <code>IndexOutOfBoundsException</code> 0N/A * If <code>len</code> is zero, 0N/A * then no bytes are read. Otherwise, the first 0N/A * byte read is stored into element <code>b[off]</code>, 0N/A * the next one into <code>b[off+1]</code>, 0N/A * and so on. The number of bytes read is, 0N/A * at most, equal to <code>len</code>. 0N/A * @param b the buffer into which the data is read. 0N/A * @param off an int specifying the offset into the data. 0N/A * @param len an int specifying the number of bytes to read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Makes an attempt to skip over 0N/A * <code>n</code> bytes 0N/A * of data from the input 0N/A * stream, discarding the skipped bytes. However, 0N/A * over some smaller number of 0N/A * bytes, possibly zero. This may result from 0N/A * number of conditions; reaching 0N/A * end of file before <code>n</code> bytes 0N/A * have been skipped is 0N/A * only one possibility. 0N/A * This method never throws an <code>EOFException</code>. 0N/A * number of bytes skipped is returned. 0N/A * @param n the number of bytes to be skipped. 0N/A * @return the number of bytes actually skipped. 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads one input byte and returns 0N/A * <code>true</code> if that byte is nonzero, 0N/A * <code>false</code> if that byte is zero. 0N/A * This method is suitable for reading 0N/A * the byte written by the <code>writeBoolean</code> 0N/A * method of interface <code>DataOutput</code>. 0N/A * @return the <code>boolean</code> value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads and returns one input byte. 0N/A * The byte is treated as a signed value in 0N/A * the range <code>-128</code> through <code>127</code>, 0N/A * This method is suitable for 0N/A * reading the byte written by the <code>writeByte</code> 0N/A * method of interface <code>DataOutput</code>. 0N/A * @return the 8-bit value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads one input byte, zero-extends 0N/A * it to type <code>int</code>, and returns 0N/A * the result, which is therefore in the range 0N/A * through <code>255</code>. 0N/A * This method is suitable for reading 0N/A * the byte written by the <code>writeByte</code> 0N/A * method of interface <code>DataOutput</code> 0N/A * if the argument to <code>writeByte</code> 0N/A * was intended to be a value in the range 0N/A * <code>0</code> through <code>255</code>. 0N/A * @return the unsigned 8-bit value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads two input bytes and returns 0N/A * a <code>short</code> value. Let <code>a</code> 0N/A * be the first byte read and <code>b</code> 0N/A * be the second byte. The value 0N/A * <p><pre><code>(short)((a << 8) | (b & 0xff)) 0N/A * is suitable for reading the bytes written 0N/A * by the <code>writeShort</code> method of 0N/A * interface <code>DataOutput</code>. 0N/A * @return the 16-bit value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads two input bytes and returns 0N/A * an <code>int</code> value in the range <code>0</code> 0N/A * through <code>65535</code>. Let <code>a</code> 0N/A * be the first byte read and 0N/A * be the second byte. The value returned is: 0N/A * <p><pre><code>(((a & 0xff) << 8) | (b & 0xff)) 0N/A * This method is suitable for reading the bytes 0N/A * written by the <code>writeShort</code> method 0N/A * of interface <code>DataOutput</code> if 0N/A * the argument to <code>writeShort</code> 0N/A * was intended to be a value in the range 0N/A * <code>0</code> through <code>65535</code>. 0N/A * @return the unsigned 16-bit value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads two input bytes and returns a <code>char</code> value. 0N/A * Let <code>a</code> 0N/A * be the first byte read and <code>b</code> 0N/A * be the second byte. The value 0N/A * <p><pre><code>(char)((a << 8) | (b & 0xff)) 0N/A * is suitable for reading bytes written by 0N/A * the <code>writeChar</code> method of interface 0N/A * <code>DataOutput</code>. 0N/A * @return the <code>char</code> value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads four input bytes and returns an 0N/A * <code>int</code> value. Let <code>a-d</code> 0N/A * be the first through fourth bytes read. The value returned is: 0N/A * (((a & 0xff) << 24) | ((b & 0xff) << 16) | 0N/A *  ((c & 0xff) << 8) | (d & 0xff)) 0N/A * This method is suitable 0N/A * for reading bytes written by the <code>writeInt</code> 0N/A * method of interface <code>DataOutput</code>. 0N/A * @return the <code>int</code> value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads eight input bytes and returns 0N/A * a <code>long</code> value. Let <code>a-h</code> 0N/A * be the first through eighth bytes read. 0N/A * The value returned is: 0N/A * (((long)(a & 0xff) << 56) | 0N/A * ((long)(b & 0xff) << 48) | 0N/A * ((long)(c & 0xff) << 40) | 0N/A * ((long)(d & 0xff) << 32) | 0N/A * ((long)(e & 0xff) << 24) | 0N/A * ((long)(f & 0xff) << 16) | 0N/A * ((long)(g & 0xff) << 8) | 0N/A * ((long)(h & 0xff))) 0N/A * This method is suitable 0N/A * for reading bytes written by the <code>writeLong</code> 0N/A * method of interface <code>DataOutput</code>. 0N/A * @return the <code>long</code> value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads four input bytes and returns 0N/A * a <code>float</code> value. It does this 0N/A * by first constructing an <code>int</code> 0N/A * value in exactly the manner 0N/A * of the <code>readInt</code> 0N/A * method, then converting this <code>int</code> 0N/A * value to a <code>float</code> in 0N/A * exactly the manner of the method <code>Float.intBitsToFloat</code>. 0N/A * This method is suitable for reading 0N/A * bytes written by the <code>writeFloat</code> 0N/A * method of interface <code>DataOutput</code>. 0N/A * @return the <code>float</code> value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads eight input bytes and returns 0N/A * a <code>double</code> value. It does this 0N/A * by first constructing a <code>long</code> 0N/A * value in exactly the manner 0N/A * of the <code>readlong</code> 0N/A * method, then converting this <code>long</code> 0N/A * value to a <code>double</code> in exactly 0N/A * the manner of the method <code>Double.longBitsToDouble</code>. 0N/A * This method is suitable for reading 0N/A * bytes written by the <code>writeDouble</code> 0N/A * method of interface <code>DataOutput</code>. 0N/A * @return the <code>double</code> value read. 0N/A * @exception EOFException if this stream reaches the end before reading 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads the next line of text from the input stream. 0N/A * It reads successive bytes, converting 0N/A * each byte separately into a character, 0N/A * until it encounters a line terminator or 0N/A * file; the characters read are then 0N/A * returned as a <code>String</code>. Note 0N/A * method processes bytes, 0N/A * it does not support input of the full Unicode 0N/A * If end of file is encountered 0N/A * before even one byte can be read, then <code>null</code> 0N/A * is returned. Otherwise, each byte that is 0N/A * read is converted to type <code>char</code> 0N/A * by zero-extension. If the character <code>'\n'</code> 0N/A * is encountered, it is discarded and reading 0N/A * ceases. If the character <code>'\r'</code> 0N/A * is encountered, it is discarded and, if 0N/A * the following byte converts  to the 0N/A * character <code>'\n'</code>, then that is 0N/A * discarded also; reading then ceases. If 0N/A * end of file is encountered before either 0N/A * of the characters <code>'\n'</code> and 0N/A * <code>'\r'</code> is encountered, reading 0N/A * ceases. Once reading has ceased, a <code>String</code> 0N/A * is returned that contains all the characters 0N/A * read and not discarded, taken in order. 0N/A * Note that every character in this string 0N/A * will have a value less than <code>\u0100</code>, 0N/A * that is, <code>(char)256</code>. 0N/A * @return the next line of text from the input stream, 0N/A * or <CODE>null</CODE> if the end of file is 0N/A * encountered before a byte can be read. 0N/A * @exception IOException if an I/O error occurs. 0N/A * Reads in a string that has been encoded using a 0N/A * <a href="#modified-utf-8">modified UTF-8</a> 0N/A * The general contract of <code>readUTF</code> 0N/A * is that it reads a representation of a Unicode 0N/A * character string encoded in modified 0N/A * UTF-8 format; this string of characters 0N/A * is then returned as a <code>String</code>. 0N/A * First, two bytes are read and used to 0N/A * construct an unsigned 16-bit integer in 0N/A * exactly the manner of the <code>readUnsignedShort</code> 0N/A * method . This integer value is called the 0N/A * <i>UTF length</i> and specifies the number 0N/A * of additional bytes to be read. These bytes 0N/A * are then converted to characters by considering 0N/A * them in groups. The length of each group 0N/A * is computed from the value of the first 0N/A * byte of the group. The byte following a 0N/A * group, if any, is the first byte of the 0N/A * If the first byte of a group 0N/A * matches the bit pattern <code>0xxxxxxx</code> 0N/A * (where <code>x</code> means "may be <code>0</code> 0N/A * or <code>1</code>"), then the group consists 0N/A * of just that byte. The byte is zero-extended 0N/A * to form a character. 0N/A * of a group matches the bit pattern <code>110xxxxx</code>, 0N/A * then the group consists of that byte <code>a</code> 0N/A * and a second byte <code>b</code>. If there 0N/A * is no byte <code>b</code> (because byte 0N/A * <code>a</code> was the last of the bytes 0N/A * to be read), or if byte <code>b</code> does 0N/A * not match the bit pattern <code>10xxxxxx</code>, 0N/A * then a <code>UTFDataFormatException</code> 0N/A * is thrown. Otherwise, the group is converted 0N/A * to the character:<p> 0N/A * <pre><code>(char)(((a& 0x1F) << 6) | (b & 0x3F)) 0N/A * If the first byte of a group 0N/A * matches the bit pattern <code>1110xxxx</code>, 0N/A * then the group consists of that byte <code>a</code> 0N/A * and two more bytes <code>b</code> and <code>c</code>. 0N/A * If there is no byte <code>c</code> (because 0N/A * byte <code>a</code> was one of the last 0N/A * two of the bytes to be read), or either 0N/A * byte <code>b</code> or byte <code>c</code> 0N/A * does not match the bit pattern <code>10xxxxxx</code>, 0N/A * then a <code>UTFDataFormatException</code> 0N/A * is thrown. Otherwise, the group is converted 0N/A * to the character:<p> 0N/A * (char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F)) 0N/A * If the first byte of a group matches the 0N/A * pattern <code>1111xxxx</code> or the pattern 0N/A * <code>10xxxxxx</code>, then a <code>UTFDataFormatException</code> 0N/A * If end of file is encountered 0N/A * at any time during this entire process, 0N/A * then an <code>EOFException</code> is thrown. 0N/A * After every group has been converted to 0N/A * a character by this process, the characters 0N/A * are gathered, in the same order in which 0N/A * their corresponding groups were read from 0N/A * the input stream, to form a <code>String</code>, 0N/A * which is returned. 0N/A * The <code>writeUTF</code> 0N/A * method of interface <code>DataOutput</code> 0N/A * may be used to write data that is suitable 0N/A * for reading by this method. 0N/A * @return a Unicode string. 0N/A * @exception EOFException if this stream reaches the end 0N/A * before reading all the bytes. 0N/A * @exception IOException if an I/O error occurs. 0N/A * @exception UTFDataFormatException if the bytes do not represent a 0N/A * valid modified UTF-8 encoding of a string.