Source for java.io.StringBufferInputStream

   1: /* StringBufferInputStream.java -- Read an String as a stream
   2:    Copyright (C) 1998, 1999, 2001, 2005  Free Software Foundation, Inc.
   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: 
  39: package java.io;
  40: 
  41: /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
  42:  * "The Java Language Specification", ISBN 0-201-63451-1
  43:  * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
  44:  * Status:  Believed complete and correct.  Deprecated in JDK 1.1.
  45:  */
  46:  
  47: /**
  48:   * This class permits a <code>String</code> to be read as an input stream.
  49:   * The low eight bits of each character in the <code>String</code> are the
  50:   * bytes that are returned. The high eight bits of each character are
  51:   * discarded.
  52:   * <p>
  53:   * The mark/reset functionality in this class behaves differently than
  54:   * normal.  The <code>mark()</code> method is always ignored and the 
  55:   * <code>reset()</code> method always resets in stream to start reading from 
  56:   * position 0 in the String.  Note that since this method does not override 
  57:   * <code>markSupported()</code> in <code>InputStream</code>, calling that 
  58:   * method will return <code>false</code>.
  59:   * <p>
  60:   * Note that this class is deprecated because it does not properly handle
  61:   * 16-bit Java characters.  It is provided for backwards compatibility only
  62:   * and should not be used for new development.  The <code>StringReader</code>
  63:   * class should be used instead.
  64:   *
  65:   * @deprecated
  66:   *
  67:   * @author Aaron M. Renn (arenn@urbanophile.com)
  68:   * @author Warren Levy (warrenl@cygnus.com)
  69:   */
  70: public class StringBufferInputStream extends InputStream
  71: {
  72:   /** The String which is the input to this stream. */
  73:   protected String buffer;
  74: 
  75:   /** Position of the next byte in buffer to be read. */
  76:   protected int pos = 0;
  77: 
  78:   /** The length of the String buffer. */
  79:   protected int count;
  80: 
  81:  /**
  82:   * Create a new <code>StringBufferInputStream</code> that will read bytes
  83:   * from the passed in <code>String</code>.  This stream will read from the
  84:   * beginning to the end of the <code>String</code>.
  85:   *
  86:   * @param s The <code>String</code> this stream will read from.
  87:   */
  88:   public StringBufferInputStream(String s)
  89:   {
  90:     buffer = s;
  91:     count = s.length();
  92:   }
  93: 
  94:  /**
  95:   * This method returns the number of bytes available to be read from this
  96:   * stream.  The value returned will be equal to <code>count - pos</code>.
  97:   *
  98:   * @return The number of bytes that can be read from this stream before
  99:   * 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: }