ByteLongObject


1   /**
2    * com.mckoi.database.global.ByteLongObject  24 Sep 2000
3    *
4    * Mckoi SQL Database ( http://www.mckoi.com/database )
5    * Copyright (C) 2000, 2001, 2002  Diehl and Associates, Inc.
6    *
7    * This program is free software; you can redistribute it and/or
8    * modify it under the terms of the GNU General Public License
9    * Version 2 as published by the Free Software Foundation.
10   *
11   * This program is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   * GNU General Public License Version 2 for more details.
15   *
16   * You should have received a copy of the GNU General Public License
17   * Version 2 along with this program; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19   *
20   * Change Log:
21   * 
22   * 
23   */
24  
25  package com.mckoi.database.global;
26  
27  import java.io.IOException  ;
28  import java.io.InputStream  ;
29  
30  /**
31   * A byte array that can be transferred between the client and server.  This
32   * is used for transferring BLOB data to/from the database engine.
33   *
34   * @author Tobias Downer
35   */
36  
37  public class ByteLongObject implements java.io.Serializable  , BlobAccessor {
38  
39    static final long serialVersionUID = -6843780673892019530L;
40  
41    /**
42     * The binary data.
43     */
44    private byte[] data;
45  
46    /**
47     * Constructor.
48     */
49    public ByteLongObject(byte[] from, int offset, int length) {
50      data = new byte[(int) length];
51      System.arraycopy(from, (int) offset, data, 0, (int) length);
52    }
53  
54    public ByteLongObject(byte[] from) {
55      this(from, 0, from.length);
56    }
57  
58    public ByteLongObject(InputStream   in, int length) throws IOException   {
59      data = new byte[length];
60      int i = 0;
61      while (i < length) {
62        int read = in.read(data, i, length - i);
63        if (read == -1) {
64          throw new IOException  ("Premature end of stream.");
65        }
66        i += read;
67      }
68    }
69  
70    /**
71     * Returns the size of the data in this object.
72     */
73    public int length() {
74      return data.length;
75    }
76  
77    /**
78     * Returns the byte at offset 'n' into the binary object.
79     */
80    public byte getByte(int n) {
81      return data[n];
82    }
83  
84    /**
85     * Returns the internal byte[] of this binary object.  Care needs to be
86     * taken when handling this object because altering the contents will
87     * change this object.
88     */
89    public byte[] getByteArray() {
90      return data;
91    }
92  
93    /**
94     * Returns an InputStream that allows us to read the entire byte long object.
95     */
96    public InputStream   getInputStream() {
97      return new BLOBInputStream();
98    }
99    
100   public String   toString() {
101     StringBuffer   buf = new StringBuffer  ();
102     if (data == null) {
103       buf.append("[ BLOB (NULL) ]");
104     }
105     else {
106       buf.append("[ BLOB size=");
107       buf.append(data.length);
108       buf.append(" ]");
109     }
110     return new String  (buf);
111   }
112 
113   /**
114    * Inner class that encapsulates the byte long object in an input stream.
115    */
116   private class BLOBInputStream extends InputStream   {
117     
118     private int index;
119     
120     public BLOBInputStream() {
121       index = 0;
122     }
123     
124     public int read() throws IOException   {
125       if (index >= length()) {
126         return -1;
127       }
128       int b = ((int) getByte(index)) & 0x0FF;
129       ++index;
130       return b;
131     }
132 
133     public int read(byte[] buf, int off, int len) throws IOException   {
134       // As per the InputStream specification.
135       if (len == 0) {
136         return 0;
137       }
138       
139       int size = length();
140       int to_read = Math.min(len, size - index);
141 
142       if (to_read <= 0) {
143         // Nothing can be read
144         return -1;
145       }
146 
147       System.arraycopy(data, index, buf, off, to_read);
148       index += to_read;
149 
150       return to_read;
151     }
152     
153   }
154   
155 }
156
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