Source for java.io.ByteArrayOutputStream

   1: /* BufferedReader.java
   2:    Copyright (C) 1998, 1999, 2000, 2001, 2003, 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:  * Status:  Complete to version 1.1.
  44:  */
  45: 
  46: /**
  47:   * This class allows data to be written to a byte array buffer and
  48:   * and then retrieved by an application.   The internal byte array
  49:   * buffer is dynamically resized to hold all the data written.  Please
  50:   * be aware that writing large amounts to data to this stream will
  51:   * cause large amounts of memory to be allocated.
  52:   * <p>
  53:   * The size of the internal buffer defaults to 32 and it is resized
  54:   * by doubling the size of the buffer.  This default size can be
  55:   * overridden by using the
  56:   * <code>gnu.java.io.ByteArrayOutputStream.initialBufferSize</code>
  57:   * property.
  58:   * <p>
  59:   * There is a constructor that specified the initial buffer size and
  60:   * that is the preferred way to set that value because it it portable
  61:   * across all Java class library implementations.
  62:   * <p>
  63:   * Note that this class also has methods that convert the byte array
  64:   * buffer to a <code>String</code> using either the system default or an
  65:   * application specified character encoding.  Thus it can handle 
  66:   * multibyte character encodings.
  67:   *
  68:   * @author Aaron M. Renn (arenn@urbanophile.com)
  69:   * @author Tom Tromey (tromey@cygnus.com)
  70:   * @date September 24, 1998 
  71:   */
  72: public class ByteArrayOutputStream extends OutputStream
  73: {
  74:   /**
  75:    * This method initializes a new <code>ByteArrayOutputStream</code>
  76:    * with the default buffer size of 32 bytes.  If a different initial
  77:    * buffer size is desired, see the constructor
  78:    * <code>ByteArrayOutputStream(int size)</code>.  For applications
  79:    * where the source code is not available, the default buffer size
  80:    * can be set using the system property
  81:    * <code>gnu.java.io.ByteArrayOutputStream.initialBufferSize</code>
  82:    */
  83:   public ByteArrayOutputStream ()
  84:   {
  85:     this (initial_buffer_size);
  86:   }
  87: 
  88:   /**
  89:    * This method initializes a new <code>ByteArrayOutputStream</code> with
  90:    * a specified initial buffer size.
  91:    *
  92:    * @param size The initial buffer size in bytes
  93:    */
  94:   public ByteArrayOutputStream (int size)
  95:   {
  96:     buf = new byte[size];
  97:     count = 0;
  98:   }
  99: 
 100:   /**
 101:    * This method discards all of the bytes that have been written to
 102:    * the internal buffer so far by setting the <code>count</code>
 103:    * variable to 0.  The internal buffer remains at its currently
 104:    * allocated size.
 105:    */
 106:   public synchronized void reset ()
 107:   {
 108:     count = 0;
 109:   }
 110: 
 111:   /**
 112:    * This method returns the number of bytes that have been written to
 113:    * the buffer so far.  This is the same as the value of the protected
 114:    * <code>count</code> variable.  If the <code>reset</code> method is
 115:    * called, then this value is reset as well.  Note that this method does
 116:    * not return the length of the internal buffer, but only the number
 117:    * of bytes that have been written to it.
 118:    *
 119:    * @return The number of bytes in the internal buffer
 120:    *
 121:    * @see #reset()
 122:    */
 123:   public int size ()
 124:   {
 125:     return count;
 126:   }
 127: 
 128:   /**
 129:    * This method returns a byte array containing the bytes that have been
 130:    * written to this stream so far.  This array is a copy of the valid
 131:    * bytes in the internal buffer and its length is equal to the number of
 132:    * valid bytes, not necessarily to the the length of the current 
 133:    * internal buffer.  Note that since this method allocates a new array,
 134:    * it should be used with caution when the internal buffer is very large.
 135:    */
 136:   public synchronized byte[] toByteArray ()
 137:   {
 138:     byte[] ret = new byte[count];
 139:     System.arraycopy(buf, 0, ret, 0, count);
 140:     return ret;
 141:   }
 142: 
 143:   /**
 144:    * Returns the bytes in the internal array as a <code>String</code>.  The
 145:    * bytes in the buffer are converted to characters using the system default
 146:    * encoding.  There is an overloaded <code>toString()</code> method that
 147:    * allows an application specified character encoding to be used.
 148:    *
 149:    * @return A <code>String</code> containing the data written to this
 150:    * stream so far
 151:    */
 152:   public String toString ()
 153:   {
 154:     return new String (buf, 0, count);
 155:   }
 156: 
 157:   /**
 158:    * Returns the bytes in the internal array as a <code>String</code>.  The
 159:    * bytes in the buffer are converted to characters using the specified
 160:    * encoding. 
 161:    *
 162:    * @param enc The name of the character encoding to use
 163:    *
 164:    * @return A <code>String</code> containing the data written to this
 165:    * stream so far
 166:    *
 167:    * @exception UnsupportedEncodingException If the named encoding is
 168:    * not available
 169:    */
 170:   public String toString (String enc) throws UnsupportedEncodingException
 171:   {
 172:     return new String (buf, 0, count, enc);
 173:   }
 174: 
 175:   /**
 176:    * This method returns the bytes in the internal array as a
 177:    * <code>String</code>.  It uses each byte in the array as the low
 178:    * order eight bits of the Unicode character value and the passed in
 179:    * parameter as the high eight bits.
 180:    * <p>
 181:    * This method does not convert bytes to characters in the proper way and
 182:    * so is deprecated in favor of the other overloaded <code>toString</code>
 183:    * methods which use a true character encoding.
 184:    *
 185:    * @param hibyte The high eight bits to use for each character in
 186:    * the <code>String</code> 
 187:    *
 188:    * @return A <code>String</code> containing the data written to this
 189:    * stream so far
 190:    *
 191:    * @deprecated
 192:    */
 193:   public String toString (int hibyte)
 194:   {
 195:     return new String (buf, 0, count, hibyte);
 196:   }
 197: 
 198:   // Resize buffer to accommodate new bytes.
 199:   private void resize (int add)
 200:   {
 201:     if (count + add > buf.length)
 202:       {
 203:     int newlen = buf.length * 2;
 204:     if (count + add > newlen)
 205:       newlen = count + add;
 206:     byte[] newbuf = new byte[newlen];
 207:     System.arraycopy(buf, 0, newbuf, 0, count);
 208:     buf = newbuf;
 209:       }
 210:   }
 211: 
 212:   /**
 213:    * This method writes the writes the specified byte into the internal
 214:    * buffer.
 215:    *
 216:    * @param oneByte The byte to be read passed as an int
 217:    */
 218:   public synchronized void write (int oneByte)
 219:   {
 220:     resize (1);
 221:     buf[count++] = (byte) oneByte;
 222:   }
 223: 
 224:   /**
 225:    * This method writes <code>len</code> bytes from the passed in array 
 226:    * <code>buf</code> starting at index <code>offset</code> into the
 227:    * internal buffer.
 228:    *
 229:    * @param buffer The byte array to write data from
 230:    * @param offset The index into the buffer to start writing data from
 231:    * @param add The number of bytes to write
 232:    */
 233:   public synchronized void write (byte[] buffer, int offset, int add)
 234:   {
 235:     // If ADD < 0 then arraycopy will throw the appropriate error for
 236:     // us.
 237:     if (add >= 0)
 238:       resize (add);
 239:     System.arraycopy(buffer, offset, buf, count, add);
 240:     count += add;
 241:   }
 242: 
 243:   /**
 244:    * This method writes all the bytes that have been written to this stream
 245:    * from the internal buffer to the specified <code>OutputStream</code>.
 246:    *
 247:    * @param out The <code>OutputStream</code> to write to
 248:    *
 249:    * @exception IOException If an error occurs
 250:    */
 251:   public synchronized void writeTo (OutputStream out) throws IOException
 252:   {
 253:     out.write(buf, 0, count);
 254:   }
 255: 
 256:   /**
 257:    * The internal buffer where the data written is stored
 258:    */
 259:   protected byte[] buf;
 260: 
 261:   /**
 262:    * The number of bytes that have been written to the buffer
 263:    */
 264:   protected int count;
 265: 
 266:   /**
 267:    * The default initial buffer size.  Specified by the JCL.
 268:    */
 269:   private static final int DEFAULT_INITIAL_BUFFER_SIZE = 32;
 270: 
 271:   // The default buffer size which can be overridden by the user.
 272:   private static final int initial_buffer_size;
 273: 
 274:   static
 275:   {
 276:     int r
 277:       = Integer.getInteger ("gnu.java.io.ByteArrayOutputStream.initialBufferSize",
 278:                 DEFAULT_INITIAL_BUFFER_SIZE).intValue ();
 279:     if (r <= 0)
 280:       r = DEFAULT_INITIAL_BUFFER_SIZE;
 281:     initial_buffer_size = r;
 282:   }
 283: }