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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.core.file;
21  
22  import java.nio.channels.FileChannel;
23  
24  /**
25   * Indicates the region of a file to be sent to the remote host.
26   *
27   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
28   */
29  public interface FileRegion {
30  
31      /**
32       * The open <tt>FileChannel<tt> from which data will be read to send to
33       * remote host.
34       *
35       * @return  An open <tt>FileChannel<tt>.
36       */
37      FileChannel getFileChannel();
38  
39      /**
40       * The current file position from which data will be read.
41       *
42       * @return  The current file position.
43       */
44      long getPosition();
45  
46      /**
47       * Updates the current file position based on the specified amount.  This
48       * increases the value returned by {@link #getPosition()} and
49       * {@link getWrittenBytes} by the given amount and decreases the value
50       * returned by {@link #getCount()} by the given {@code amount}.
51       *
52       * @param amount  The new value for the file position.
53       */
54      void update(long amount);
55  
56      /**
57       * The number of bytes remaining to be written from the file to the remote
58       * host.
59       *
60       * @return  The number of bytes remaining to be written.
61       */
62      long getRemainingBytes();
63  
64      /**
65       * The total number of bytes already written.
66       *
67       * @return  The total number of bytes already written.
68       */
69      long getWrittenBytes();
70  
71      /**
72       * Provides an absolute filename for the underlying FileChannel.
73       * 
74       * @return  the absolute filename, or <tt>null</tt> if the FileRegion
75       *   does not know the filename
76       */
77      String getFilename();
78  }