LimitedInputStream


1   package com.quadcap.io;
2   
3   /* Copyright 1997 - 2003 Quadcap Software.  All rights reserved.
4    *
5    * This software is distributed under the Quadcap Free Software License.
6    * This software may be used or modified for any purpose, personal or
7    * commercial.  Open Source redistributions are permitted.  Commercial
8    * redistribution of larger works derived from, or works which bundle
9    * this software requires a "Commercial Redistribution License"; see
10   * http://www.quadcap.com/purchase.
11   *
12   * Redistributions qualify as "Open Source" under  one of the following terms:
13   *   
14   *    Redistributions are made at no charge beyond the reasonable cost of
15   *    materials and delivery.
16   *
17   *    Redistributions are accompanied by a copy of the Source Code or by an
18   *    irrevocable offer to provide a copy of the Source Code for up to three
19   *    years at the cost of materials and delivery.  Such redistributions
20   *    must allow further use, modification, and redistribution of the Source
21   *    Code under substantially the same terms as this license.
22   *
23   * Redistributions of source code must retain the copyright notices as they
24   * appear in each source code file, these license terms, and the
25   * disclaimer/limitation of liability set forth as paragraph 6 below.
26   *
27   * Redistributions in binary form must reproduce this Copyright Notice,
28   * these license terms, and the disclaimer/limitation of liability set
29   * forth as paragraph 6 below, in the documentation and/or other materials
30   * provided with the distribution.
31   *
32   * The Software is provided on an "AS IS" basis.  No warranty is
33   * provided that the Software is free of defects, or fit for a
34   * particular purpose.  
35   *
36   * Limitation of Liability. Quadcap Software shall not be liable
37   * for any damages suffered by the Licensee or any third party resulting
38   * from use of the Software.
39   */
40  
41  import java.io.InputStream  ;
42  import java.io.IOException  ;
43  
44  /**
45   * This class implements a sort of 'head' operation, creating a new
46   * input stream as a filter stream on top of an existing stream, returning
47   * only the first "N" bytes.
48   *
49   * @author Stan Bailes
50   */
51  public class LimitedInputStream extends InputStream   {
52      InputStream                           in;
53      int                                 cnt = 0;
54      int                                 limit;
55  
56      /**
57       * Construct a new LimitedInputStream, attached to the specified
58       * input stream and with the specified limit.
59       *
60       * @param in the input stream
61       * @param limit the number of bytes to read
62       */
63      public LimitedInputStream(InputStream   in, int limit) {
64          this.in = in;
65          this.limit = limit;
66      }
67  
68      /**
69       * Read a byte from this stream, returning -1 if the underlying
70       * stream returns EOF, or if we've reached our limit.
71       *
72       * @exception IOException may be thrown
73       */
74      public int read() throws IOException   {
75          if (cnt++ >= limit) return -1;
76          return in.read();
77      }
78  }
79
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