Source for java.io.ByteArrayOutputStream

   1: /* BufferedReader.java
   2:    Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005
   3:    Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11:  
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: 
  40: package java.io;
  41: 
  42: /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
  43:  * "The Java Language Specification", ISBN 0-201-63451-1
  44:  * Status:  Complete to version 1.1.
  45:  */
  46: 
  47: /**
  48:   * This class allows data to be written to a byte array buffer and
  49:   * and then retrieved by an application.   The internal byte array
  50:   * buffer is dynamically resized to hold all the data written.  Please
  51:   * be aware that writing large amounts to data to this stream will
  52:   * cause large amounts of memory to be allocated.
  53:   * <p>
  54:   * The size of the internal buffer defaults to 32 and it is resized
  55:   * by doubling the size of the buffer.  This default size can be
  56:   * overridden by using the
  57:   * <code>gnu.java.io.ByteArrayOutputStream.initialBufferSize</code>
  58:   * property.
  59:   * <p>
  60:   * There is a constructor that specified the initial buffer size and
  61:   * that is the preferred way to set that value because it it portable
  62:   * across all Java class library implementations.
  63:   * <p>
  64:   * Note that this class also has methods that convert the byte array
  65:   * buffer to a <code>String</code> using either the system default or an
  66:   * application specified character encoding.  Thus it can handle 
  67:   * multibyte character encodings.
  68:   *
  69:   * @author Aaron M. Renn (arenn@urbanophile.com)
  70:   * @author Tom Tromey (tromey@cygnus.com)
  71:   * @date September 24, 1998 
  72:   */
  73: public class ByteArrayOutputStream extends OutputStream
  74: {
  75:   /**
  76:    * This method initializes a new <code>ByteArrayOutputStream</code>
  77:    * with the default buffer size of 32 bytes.  If a different initial
  78:    * buffer size is desired, see the constructor
  79:    * <code>ByteArrayOutputStream(int size)</code>.  For applications
  80:    * where the source code is not available, the default buffer size
  81:    * can be set using the system property
  82:    * <code>gnu.java.io.ByteArrayOutputStream.initialBufferSize</code>
  83:    */
  84:   public ByteArrayOutputStream ()
  85:   {
  86:     this (initial_buffer_size);
  87:   }
  88: 
  89:   /**
  90:    * This method initializes a new <code>ByteArrayOutputStream</code> with
  91:    * a specified initial buffer size.
  92:    *
  93:    * @param size The initial buffer size in bytes
  94:    */
  95:   public ByteArrayOutputStream (int size)
  96:   {
  97:     buf = new byte[size];
  98:     count = 0;
  99:   }
 100: 
 101:   /**
 102:    * This method discards all of the bytes that have been written to
 103:    * the internal buffer so far by setting the <code>count</code>
 104:    * variable to 0.  The internal buffer remains at its currently
 105:    * allocated size.
 106:    */
 107:   public synchronized void reset ()
 108:   {
 109:     count = 0;
 110:   }
 111: 
 112:   /**
 113:    * This method returns the number of bytes that have been written to
 114:    * the buffer so far.  This is the same as the value of the protected
 115:    * <code>count</code> variable.  If the <code>reset</code> method is
 116:    * called, then this value is reset as well.  Note that this method does
 117:    * not return the length of the internal buffer, but only the number
 118:    * of bytes that have been written to it.
 119:    *
 120:    * @return The number of bytes in the internal buffer
 121:    *
 122:    * @see #reset()
 123:    */
 124:   public int size ()
 125:   {
 126:     return count;
 127:   }
 128: 
 129:   /**
 130:    * This method returns a byte array containing the bytes that have been
 131:    * written to this stream so far.  This array is a copy of the valid
 132:    * bytes in the internal buffer and its length is equal to the number of
 133:    * valid bytes, not necessarily to the the length of the current 
 134:    * internal buffer.  Note that since this method allocates a new array,
 135:    * it should be used with caution when the internal buffer is very large.
 136:    */
 137:   public synchronized byte[] toByteArray ()
 138:   {
 139:     byte[] ret = new byte[count];
 140:     System.arraycopy(buf, 0, ret, 0, count);
 141:     return ret;
 142:   }
 143: 
 144:   /**
 145:    * Returns the bytes in the internal array as a <code>String</code>.  The
 146:    * bytes in the buffer are converted to characters using the system default
 147:    * encoding.  There is an overloaded <code>toString()</code> method that
 148:    * allows an application specified character encoding to be used.
 149:    *
 150:    * @return A <code>String</code> containing the data written to this
 151:    * stream so far
 152:    */
 153:   public String toString ()
 154:   {
 155:     return new String (buf, 0, count);
 156:   }
 157: 
 158:   /**
 159:    * Returns the bytes in the internal array as a <code>String</code>.  The
 160:    * bytes in the buffer are converted to characters using the specified
 161:    * encoding. 
 162:    *
 163:    * @param enc The name of the character encoding to use
 164:    *
 165:    * @return A <code>String</code> containing the data written to this
 166:    * stream so far
 167:    *
 168:    * @exception UnsupportedEncodingException If the named encoding is
 169:    * not available
 170:    */
 171:   public String toString (String enc) throws UnsupportedEncodingException
 172:   {
 173:     return new String (buf, 0, count, enc);
 174:   }
 175: 
 176:   /**
 177:    * This method returns the bytes in the internal array as a
 178:    * <code>String</code>.  It uses each byte in the array as the low
 179:    * order eight bits of the Unicode character value and the passed in
 180:    * parameter as the high eight bits.
 181:    * <p>
 182:    * This method does not convert bytes to characters in the proper way and
 183:    * so is deprecated in favor of the other overloaded <code>toString</code>
 184:    * methods which use a true character encoding.
 185:    *
 186:    * @param hibyte The high eight bits to use for each character in
 187:    * the <code>String</code> 
 188:    *
 189:    * @return A <code>String</code> containing the data written to this
 190:    * stream so far
 191:    *
 192:    * @deprecated
 193:    */
 194:   public String toString (int hibyte)
 195:   {
 196:     return new String (buf, hibyte, 0, count);
 197:   }
 198: 
 199:   // Resize buffer to accommodate new bytes.
 200:   private void resize (int add)
 201:   {
 202:     if (count + add > buf.length)
 203:       {
 204:     int newlen = buf.length * 2;
 205:     if (count + add > newlen)
 206:       newlen = count + add;
 207:     byte[] newbuf = new byte[newlen];
 208:     System.arraycopy(buf, 0, newbuf, 0, count);
 209:     buf = newbuf;
 210:       }
 211:   }
 212: 
 213:   /**
 214:    * This method writes the writes the specified byte into the internal
 215:    * buffer.
 216:    *
 217:    * @param oneByte The byte to be read passed as an int
 218:    */
 219:   public synchronized void write (int oneByte)
 220:   {
 221:     resize (1);
 222:     buf[count++] = (byte) oneByte;
 223:   }
 224: 
 225:   /**
 226:    * This method writes <code>len</code> bytes from the passed in array 
 227:    * <code>buf</code> starting at index <code>offset</code> into the
 228:    * internal buffer.
 229:    *
 230:    * @param buffer The byte array to write data from
 231:    * @param offset The index into the buffer to start writing data from
 232:    * @param add The number of bytes to write
 233:    */
 234:   public synchronized void write (byte[] buffer, int offset, int add)
 235:   {
 236:     // If ADD < 0 then arraycopy will throw the appropriate error for
 237:     // us.
 238:     if (add >= 0)
 239:       resize (add);
 240:     System.arraycopy(buffer, offset, buf, count, add);
 241:     count += add;
 242:   }
 243: 
 244:   /**
 245:    * This method writes all the bytes that have been written to this stream
 246:    * from the internal buffer to the specified <code>OutputStream</code>.
 247:    *
 248:    * @param out The <code>OutputStream</code> to write to
 249:    *
 250:    * @exception IOException If an error occurs
 251:    */
 252:   public synchronized void writeTo (OutputStream out) throws IOException
 253:   {
 254:     out.write(buf, 0, count);
 255:   }
 256: 
 257:   /**
 258:    * The internal buffer where the data written is stored
 259:    */
 260:   protected byte[] buf;
 261: 
 262:   /**
 263:    * The number of bytes that have been written to the buffer
 264:    */
 265:   protected int count;
 266: 
 267:   /**
 268:    * The default initial buffer size.  Specified by the JCL.
 269:    */
 270:   private static final int DEFAULT_INITIAL_BUFFER_SIZE = 32;
 271: 
 272:   // The default buffer size which can be overridden by the user.
 273:   private static final int initial_buffer_size;
 274: 
 275:   static
 276:   {
 277:     int r
 278:       = Integer.getInteger ("gnu.java.io.ByteArrayOutputStream.initialBufferSize",
 279:                 DEFAULT_INITIAL_BUFFER_SIZE).intValue ();
 280:     if (r <= 0)
 281:       r = DEFAULT_INITIAL_BUFFER_SIZE;
 282:     initial_buffer_size = r;
 283:   }
 284: }