001/*
002 * Copyright 2010-2014 UnboundID Corp.
003 * All Rights Reserved.
004 */
005/*
006 * Copyright (C) 2010-2014 UnboundID Corp.
007 *
008 * This program is free software; you can redistribute it and/or modify
009 * it under the terms of the GNU General Public License (GPLv2 only)
010 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
011 * as published by the Free Software Foundation.
012 *
013 * This program is distributed in the hope that it will be useful,
014 * but WITHOUT ANY WARRANTY; without even the implied warranty of
015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
016 * GNU General Public License for more details.
017 *
018 * You should have received a copy of the GNU General Public License
019 * along with this program; if not, see <http://www.gnu.org/licenses>.
020 */
021package com.unboundid.util;
022
023
024
025import java.io.IOException;
026import java.io.OutputStream;
027import java.io.Serializable;
028
029import static com.unboundid.util.UtilityMessages.*;
030
031
032
033/**
034 * This class provides an {@code OutputStream} implementation that writes data
035 * to a provided byte array.  It is similar to the
036 * {@code java.io.ByteArrayOutputStream} class, except that it allows you to
037 * pass in the array that it uses, and the array will not grow over time.
038 */
039@Mutable()
040@ThreadSafety(level=ThreadSafetyLevel.NOT_THREADSAFE)
041public final class FixedArrayOutputStream
042       extends OutputStream
043       implements Serializable
044{
045  /**
046   * The serial version UID for this serializable class.
047   */
048  private static final long serialVersionUID = 4678108653480347534L;
049
050
051
052  // The byte array used by this class.
053  private final byte[] array;
054
055  // The initial position for this array.
056  private final int initialPosition;
057
058  // The maximum number of bytes that may be written.
059  private final int length;
060
061  // The maximum position at which data may be written.
062  private final int maxPosition;
063
064  // The current position at which data may be written.
065  private int pos;
066
067
068
069  /**
070   * Creates a new output stream that will write data to the provided array.
071   * It will use the entire array.
072   *
073   * @param  array  The array to which data will be written.  It must not be
074   *                {@code null}.
075   */
076  public FixedArrayOutputStream(final byte[] array)
077  {
078    this(array, 0, array.length);
079  }
080
081
082
083  /**
084   * Creates a new output stream that will write data to the provided array.
085   * It will use the specified portion of the array.
086   *
087   * @param  array  The array to which data will be written.  It must not be
088   *                {@code null}.
089   * @param  pos    The position at which to start writing data.  It must be
090   *                greater than or equal to zero and less than or equal to the
091   *                length of the array.
092   * @param  len    The maximum number of bytes that may be written.  It must
093   *                be greater than or equal to zero and less than or equal to
094   *                the difference between the length of the array and the
095   *                provided {@code pos} value.
096   */
097  public FixedArrayOutputStream(final byte[] array, final int pos,
098                                   final int len)
099  {
100    this.array = array;
101    this.pos   = pos;
102
103    initialPosition = pos;
104    maxPosition     = pos + len;
105    length          = len;
106
107    Validator.ensureTrue((pos >= 0),
108         "The position must be greater than or equal to zero.");
109    Validator.ensureTrue((len >= 0),
110         "The length must be greater than or equal to zero.");
111    Validator.ensureTrue((maxPosition <= array.length),
112         "The sum of pos and len must not exceed the array length.");
113  }
114
115
116
117  /**
118   * Retrieves the backing array used by this output stream.
119   *
120   * @return  The backing array used by this output stream.
121   */
122  public byte[] getBackingArray()
123  {
124    return array;
125  }
126
127
128
129  /**
130   * Retrieves the initial position provided when this output stream was
131   * created.
132   *
133   * @return  The initial position provided when this output stream was created.
134   */
135  public int getInitialPosition()
136  {
137    return initialPosition;
138  }
139
140
141
142  /**
143   * Retrieves the maximum number of bytes that may be written to this output
144   * stream.
145   *
146   * @return  The maximum number of bytes that may be written to this output
147   *          stream.
148   */
149  public int getLength()
150  {
151    return length;
152  }
153
154
155
156  /**
157   * Retrieves the number of bytes that have been written so far to this output
158   * stream.
159   *
160   * @return  The number of bytes that have been written so far to this output
161   *          stream.
162   */
163  public int getBytesWritten()
164  {
165    return (pos - initialPosition);
166  }
167
168
169
170  /**
171   * Closes this output stream.  This has no effect.
172   */
173  @Override()
174  public void close()
175  {
176    // No implementation required.
177  }
178
179
180
181  /**
182   * Flushes this output stream.  This has no effect.
183   */
184  @Override()
185  public void flush()
186  {
187    // No implementation required.
188  }
189
190
191
192  /**
193   * Writes the provided byte to this output stream.
194   *
195   * @param  b  The byte to be written.
196   *
197   * @throws  IOException  If an attempt was made to write beyond the end of the
198   *                       array.
199   */
200  @Override()
201  public void write(final int b)
202         throws IOException
203  {
204    if (pos >= maxPosition)
205    {
206      throw new IOException(ERR_FIXED_ARRAY_OS_WRITE_BEYOND_END.get());
207    }
208
209    array[pos++] = (byte) b;
210  }
211
212
213
214  /**
215   * Writes the contents of the provided array to this output stream.
216   *
217   * @param  b  The byte array containing the data to be written.  It must not
218   *            be {@code null}.
219   *
220   * @throws  IOException  If an attempt was made to write beyond the end of the
221   *                       array.
222   */
223  @Override()
224  public void write(final byte[] b)
225         throws IOException
226  {
227    write(b, 0, b.length);
228  }
229
230
231
232  /**
233   * Writes the contents of the provided array to this output stream.
234   *
235   * @param  b    The byte array containing the data to be written.  It must not
236   *              be {@code null}.
237   * @param  off  The offset within the provided array of the beginning of the
238   *              data to be written.  It must be greater than or equal to zero
239   *              and less than or equal to the length of the provided array.
240   * @param  len  The number of bytes to be written.  It must be greater than or
241   *              equal to zero, and the sum of {@code off} and {@code len} must
242   *              be less than the length of the provided array.
243   *
244   * @throws  IOException  If an attempt was made to write beyond the end of the
245   *                       array.
246   */
247  @Override()
248  public void write(final byte[] b, final int off, final int len)
249         throws IOException
250  {
251    Validator.ensureTrue((off >= 0),
252         "The provided offset must be greater than or equal to zero.");
253    Validator.ensureTrue((len >= 0),
254         "The provided length must be greater than or equal to zero.");
255    Validator.ensureTrue(((off + len) <= b.length),
256         "The sum of off and len must not exceed the array length.");
257
258    if ((pos + len) > maxPosition)
259    {
260      throw new IOException(ERR_FIXED_ARRAY_OS_WRITE_BEYOND_END.get());
261    }
262
263    System.arraycopy(b, off, array, pos, len);
264    pos += len;
265  }
266}