MonitorInputStream


1   /*
2    * Copyright 2002-2005 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.vfs.util;
17  
18  import java.io.BufferedInputStream  ;
19  import java.io.IOException  ;
20  import java.io.InputStream  ;
21  
22  /**
23   * An InputStream that provides buffering and end-of-stream monitoring.
24   *
25   * @author <a HREF="mailto:adammurdoch@apache.org">Adam Murdoch</a>
26   */
27  public class MonitorInputStream
28      extends BufferedInputStream  
29  {
30      private boolean finished;
31      private long count;
32  
33      public MonitorInputStream(final InputStream   in)
34      {
35          super(in);
36          count = 0;
37      }
38  
39      /**
40       * Reads a character.
41       */
42      public int read() throws IOException  
43      {
44          if (finished)
45          {
46              return -1;
47          }
48  
49          final int ch = super.read();
50          if (ch != -1)
51          {
52              count++;
53              return ch;
54          }
55  
56          // End-of-stream
57          close();
58          return -1;
59      }
60  
61      /**
62       * Reads bytes from this input stream.error occurs.
63       */
64      public int read(final byte[] buffer, final int offset, final int length)
65          throws IOException  
66      {
67          if (finished)
68          {
69              return -1;
70          }
71  
72          final int nread = super.read(buffer, offset, length);
73          if (nread != -1)
74          {
75              count += nread;
76              return nread;
77          }
78  
79          // End-of-stream
80          close();
81          return -1;
82      }
83  
84      /**
85       * Closes this input stream and releases any system resources
86       * associated with the stream.
87       */
88      public void close() throws IOException  
89      {
90          if (finished)
91          {
92              return;
93          }
94  
95          // Close the stream
96          IOException   exc = null;
97          try
98          {
99              super.close();
100         }
101         catch (final IOException   ioe)
102         {
103             exc = ioe;
104         }
105 
106         // Notify that the stream has been closed
107         try
108         {
109             onClose();
110         }
111         catch (final IOException   ioe)
112         {
113             exc = ioe;
114         }
115 
116         finished = true;
117         if (exc != null)
118         {
119             throw exc;
120         }
121     }
122 
123     /**
124      * Called after the stream has been closed.  This implementation does
125      * nothing.
126      */
127     protected void onClose() throws IOException  
128     {
129     }
130 
131     /**
132      * Get the nuber of bytes read by this input stream
133      */
134     public long getCount()
135     {
136         return count;
137     }
138 }
139
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