001/* StringBufferInputStream.java -- Read an String as a stream 002 Copyright (C) 1998, 1999, 2001, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package java.io; 040 041/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 042 * "The Java Language Specification", ISBN 0-201-63451-1 043 * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. 044 * Status: Believed complete and correct. Deprecated in JDK 1.1. 045 */ 046 047/** 048 * This class permits a <code>String</code> to be read as an input stream. 049 * The low eight bits of each character in the <code>String</code> are the 050 * bytes that are returned. The high eight bits of each character are 051 * discarded. 052 * <p> 053 * The mark/reset functionality in this class behaves differently than 054 * normal. The <code>mark()</code> method is always ignored and the 055 * <code>reset()</code> method always resets in stream to start reading from 056 * position 0 in the String. Note that since this method does not override 057 * <code>markSupported()</code> in <code>InputStream</code>, calling that 058 * method will return <code>false</code>. 059 * <p> 060 * Note that this class is deprecated because it does not properly handle 061 * 16-bit Java characters. It is provided for backwards compatibility only 062 * and should not be used for new development. The <code>StringReader</code> 063 * class should be used instead. 064 * 065 * @deprecated 066 * 067 * @author Aaron M. Renn (arenn@urbanophile.com) 068 * @author Warren Levy (warrenl@cygnus.com) 069 */ 070public class StringBufferInputStream extends InputStream 071{ 072 /** The String which is the input to this stream. */ 073 protected String buffer; 074 075 /** Position of the next byte in buffer to be read. */ 076 protected int pos = 0; 077 078 /** The length of the String buffer. */ 079 protected int count; 080 081 /** 082 * Create a new <code>StringBufferInputStream</code> that will read bytes 083 * from the passed in <code>String</code>. This stream will read from the 084 * beginning to the end of the <code>String</code>. 085 * 086 * @param s The <code>String</code> this stream will read from. 087 */ 088 public StringBufferInputStream(String s) 089 { 090 buffer = s; 091 count = s.length(); 092 } 093 094 /** 095 * This method returns the number of bytes available to be read from this 096 * stream. The value returned will be equal to <code>count - pos</code>. 097 * 098 * @return The number of bytes that can be read from this stream before 099 * blocking, which is all of them 100 */ 101 public int available() 102 { 103 return count - pos; 104 } 105 106 /** 107 * This method reads one byte from the stream. The <code>pos</code> counter 108 * is advanced to the next byte to be read. The byte read is returned as 109 * an int in the range of 0-255. If the stream position is already at the 110 * end of the buffer, no byte is read and a -1 is returned in order to 111 * indicate the end of the stream. 112 * 113 * @return The byte read, or -1 if end of stream 114 */ 115 public int read() 116 { 117 if (pos >= count) 118 return -1; // EOF 119 120 return ((int) buffer.charAt(pos++)) & 0xFF; 121 } 122 123/** 124 * This method reads bytes from the stream and stores them into a caller 125 * supplied buffer. It starts storing the data at index <code>offset</code> 126 * into the buffer and attempts to read <code>len</code> bytes. This method 127 * can return before reading the number of bytes requested if the end of the 128 * stream is encountered first. The actual number of bytes read is 129 * returned. If no bytes can be read because the stream is already at 130 * the end of stream position, a -1 is returned. 131 * <p> 132 * This method does not block. 133 * 134 * @param b The array into which the bytes read should be stored. 135 * @param off The offset into the array to start storing bytes 136 * @param len The requested number of bytes to read 137 * 138 * @return The actual number of bytes read, or -1 if end of stream. 139 */ 140 public int read(byte[] b, int off, int len) 141 { 142 if (off < 0 || len < 0 || off + len > b.length) 143 throw new ArrayIndexOutOfBoundsException(); 144 145 if (pos >= count) 146 return -1; // EOF 147 148 int numRead = Math.min(len, count - pos); 149 if (numRead < 0) 150 return 0; 151 152 buffer.getBytes(pos, pos + numRead, b, off); 153 pos += numRead; 154 return numRead; 155 } 156 157 /** 158 * This method sets the read position in the stream to the beginning 159 * setting the <code>pos</code> variable equal to 0. Note that this differs 160 * from the common implementation of the <code>reset()</code> method. 161 */ 162 public void reset() 163 { 164 pos = 0; 165 } 166 167 /** 168 * This method attempts to skip the requested number of bytes in the 169 * input stream. It does this by advancing the <code>pos</code> value by the 170 * specified number of bytes. It this would exceed the length of the 171 * buffer, then only enough bytes are skipped to position the stream at 172 * the end of the buffer. The actual number of bytes skipped is returned. 173 * 174 * @param n The requested number of bytes to skip 175 * 176 * @return The actual number of bytes skipped. 177 */ 178 public long skip(long n) 179 { 180 if (n < 0) 181 return 0L; 182 183 long actualSkip = Math.min(n, count - pos); 184 pos += actualSkip; 185 return actualSkip; 186 } 187}