1    
2    /* ====================================================================
3     * The Apache Software License, Version 1.1
4     *
5     * Copyright (c) 2002 The Apache Software Foundation.  All rights
6     * reserved.
7     *
8     * Redistribution and use in source and binary forms, with or without
9     * modification, are permitted provided that the following conditions
10    * are met:
11    *
12    * 1. Redistributions of source code must retain the above copyright
13    *    notice, this list of conditions and the following disclaimer.
14    *
15    * 2. Redistributions in binary form must reproduce the above copyright
16    *    notice, this list of conditions and the following disclaimer in
17    *    the documentation and/or other materials provided with the
18    *    distribution.
19    *
20    * 3. The end-user documentation included with the redistribution,
21    *    if any, must include the following acknowledgment:
22    *       "This product includes software developed by the
23    *        Apache Software Foundation (http://www.apache.org/)."
24    *    Alternately, this acknowledgment may appear in the software itself,
25    *    if and wherever such third-party acknowledgments normally appear.
26    *
27    * 4. The names "Apache" and "Apache Software Foundation" and
28    *    "Apache POI" must not be used to endorse or promote products
29    *    derived from this software without prior written permission. For
30    *    written permission, please contact apache@apache.org.
31    *
32    * 5. Products derived from this software may not be called "Apache",
33    *    "Apache POI", nor may "Apache" appear in their name, without
34    *    prior written permission of the Apache Software Foundation.
35    *
36    * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
37    * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
38    * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
39    * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
40    * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41    * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
42    * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
43    * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
44    * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
45    * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
46    * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
47    * SUCH DAMAGE.
48    * ====================================================================
49    *
50    * This software consists of voluntary contributions made by many
51    * individuals on behalf of the Apache Software Foundation.  For more
52    * information on the Apache Software Foundation, please see
53    * <http://www.apache.org/>.
54    */
55   
56   package org.apache.poi.util;
57   
58   import org.apache.poi.util.LittleEndian.BufferUnderrunException;
59   
60   import java.io.*;
61   
62   /**
63    * representation of a short (16-bit) field at a fixed location within
64    * a byte array
65    *
66    * @author Marc Johnson (mjohnson at apache dot org
67    */
68   
69   public class ShortField
70       implements FixedField
71   {
72       private short     _value;
73       private final int _offset;
74   
75       /**
76        * construct the ShortField with its offset into its containing
77        * byte array
78        *
79        * @param offset of the field within its byte array
80        *
81        * @exception ArrayIndexOutOfBoundsException if offset is negative
82        */
83   
84       public ShortField(final int offset)
85           throws ArrayIndexOutOfBoundsException
86       {
87           if (offset < 0)
88           {
89               throw new ArrayIndexOutOfBoundsException("Illegal offset: "
90                                                        + offset);
91           }
92           _offset = offset;
93       }
94   
95       /**
96        * construct the ShortField with its offset into its containing
97        * byte array and initialize its value
98        *
99        * @param offset of the field within its byte array
100       * @param value the initial value
101       *
102       * @exception ArrayIndexOutOfBoundsException if offset is negative
103       */
104  
105      public ShortField(final int offset, final short value)
106          throws ArrayIndexOutOfBoundsException
107      {
108          this(offset);
109          set(value);
110      }
111  
112      /**
113       * Construct the ShortField with its offset into its containing
114       * byte array and initialize its value from its byte array
115       *
116       * @param offset of the field within its byte array
117       * @param data the byte array to read the value from
118       *
119       * @exception ArrayIndexOutOfBoundsException if the offset is not
120       *            within the range of 0..(data.length - 1)
121       */
122  
123      public ShortField(final int offset, final byte [] data)
124          throws ArrayIndexOutOfBoundsException
125      {
126          this(offset);
127          readFromBytes(data);
128      }
129  
130      /**
131       * construct the ShortField with its offset into its containing
132       * byte array, initialize its value, and write its value to its
133       * byte array
134       *
135       * @param offset of the field within its byte array
136       * @param value the initial value
137       * @param data the byte array to write the value to
138       *
139       * @exception ArrayIndexOutOfBoundsException if offset is negative
140       */
141  
142      public ShortField(final int offset, final short value, final byte [] data)
143          throws ArrayIndexOutOfBoundsException
144      {
145          this(offset);
146          set(value, data);
147      }
148  
149      /**
150       * get the ShortField's current value
151       *
152       * @return current value
153       */
154  
155      public short get()
156      {
157          return _value;
158      }
159  
160      /**
161       * set the ShortField's current value
162       *
163       * @param value to be set
164       */
165  
166      public void set(final short value)
167      {
168          _value = value;
169      }
170  
171      /**
172       * set the ShortField's current value and write it to a byte array
173       *
174       * @param value to be set
175       * @param data the byte array to write the value to
176       *
177       * @exception ArrayIndexOutOfBoundsException if the offset is out
178       *            of range
179       */
180  
181      public void set(final short value, final byte [] data)
182          throws ArrayIndexOutOfBoundsException
183      {
184          _value = value;
185          writeToBytes(data);
186      }
187  
188      /* ********** START implementation of FixedField ********** */
189  
190      /**
191       * set the value from its offset into an array of bytes
192       *
193       * @param data the byte array from which the value is to be read
194       *
195       * @exception ArrayIndexOutOfBoundsException if the offset is out
196       *            of range
197       */
198  
199      public void readFromBytes(final byte [] data)
200          throws ArrayIndexOutOfBoundsException
201      {
202          _value = LittleEndian.getShort(data, _offset);
203      }
204  
205      /**
206       * set the value from an InputStream
207       *
208       * @param stream the InputStream from which the value is to be
209       *               read
210       *
211       * @exception BufferUnderrunException if there is not enough data
212       *            available from the InputStream
213       * @exception IOException if an IOException is thrown from reading
214       *            the InputStream
215       */
216  
217      public void readFromStream(final InputStream stream)
218          throws IOException, BufferUnderrunException
219      {
220          _value = LittleEndian.readShort(stream);
221      }
222  
223      /**
224       * write the value out to an array of bytes at the appropriate
225       * offset
226       *
227       * @param data the array of bytes to which the value is to be
228       *             written
229       *
230       * @exception ArrayIndexOutOfBoundsException if the offset is out
231       *            of range
232       */
233  
234      public void writeToBytes(final byte [] data)
235          throws ArrayIndexOutOfBoundsException
236      {
237          LittleEndian.putShort(data, _offset, _value);
238      }
239  
240      /**
241       * return the value as a String
242       *
243       * @return the value as a String
244       */
245  
246      public String toString()
247      {
248          return String.valueOf(_value);
249      }
250  
251      /* **********  END  implementation of FixedField ********** */
252  }   // end public class ShortField
253  
254