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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. 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, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.handler.stream;
17  
18  import static org.jboss.netty.buffer.ChannelBuffers.*;
19  
20  import java.io.File;
21  import java.io.IOException;
22  import java.io.RandomAccessFile;
23  
24  import org.jboss.netty.channel.FileRegion;
25  
26  /**
27   * A {@link ChunkedInput} that fetches data from a file chunk by chunk.
28   * <p>
29   * If your operating system supports
30   * <a href="http://en.wikipedia.org/wiki/Zero-copy">zero-copy file transfer</a>
31   * such as {@code sendfile()}, you might want to use {@link FileRegion} instead.
32   */
33  public class ChunkedFile implements ChunkedInput {
34  
35      private final RandomAccessFile file;
36      private final long startOffset;
37      private final long endOffset;
38      private final int chunkSize;
39      private long offset;
40  
41      /**
42       * Creates a new instance that fetches data from the specified file.
43       */
44      public ChunkedFile(File file) throws IOException {
45          this(file, ChunkedStream.DEFAULT_CHUNK_SIZE);
46      }
47  
48      /**
49       * Creates a new instance that fetches data from the specified file.
50       *
51       * @param chunkSize the number of bytes to fetch on each
52       *                  {@link #nextChunk()} call
53       */
54      public ChunkedFile(File file, int chunkSize) throws IOException {
55          this(new RandomAccessFile(file, "r"), chunkSize);
56      }
57  
58      /**
59       * Creates a new instance that fetches data from the specified file.
60       */
61      public ChunkedFile(RandomAccessFile file) throws IOException {
62          this(file, ChunkedStream.DEFAULT_CHUNK_SIZE);
63      }
64  
65      /**
66       * Creates a new instance that fetches data from the specified file.
67       *
68       * @param chunkSize the number of bytes to fetch on each
69       *                  {@link #nextChunk()} call
70       */
71      public ChunkedFile(RandomAccessFile file, int chunkSize) throws IOException {
72          this(file, 0, file.length(), chunkSize);
73      }
74  
75      /**
76       * Creates a new instance that fetches data from the specified file.
77       *
78       * @param offset the offset of the file where the transfer begins
79       * @param length the number of bytes to transfer
80       * @param chunkSize the number of bytes to fetch on each
81       *                  {@link #nextChunk()} call
82       */
83      public ChunkedFile(RandomAccessFile file, long offset, long length, int chunkSize) throws IOException {
84          if (file == null) {
85              throw new NullPointerException("file");
86          }
87          if (offset < 0) {
88              throw new IllegalArgumentException(
89                      "offset: " + offset + " (expected: 0 or greater)");
90          }
91          if (length < 0) {
92              throw new IllegalArgumentException(
93                      "length: " + length + " (expected: 0 or greater)");
94          }
95          if (chunkSize <= 0) {
96              throw new IllegalArgumentException(
97                      "chunkSize: " + chunkSize +
98                      " (expected: a positive integer)");
99          }
100 
101         this.file = file;
102         this.offset = startOffset = offset;
103         endOffset = offset + length;
104         this.chunkSize = chunkSize;
105 
106         file.seek(offset);
107     }
108 
109     /**
110      * Returns the offset in the file where the transfer began.
111      */
112     public long getStartOffset() {
113         return startOffset;
114     }
115 
116     /**
117      * Returns the offset in the file where the transfer will end.
118      */
119     public long getEndOffset() {
120         return endOffset;
121     }
122 
123     /**
124      * Returns the offset in the file where the transfer is happening currently.
125      */
126     public long getCurrentOffset() {
127         return offset;
128     }
129 
130     public boolean hasNextChunk() throws Exception {
131         return offset < endOffset && file.getChannel().isOpen();
132     }
133 
134     public boolean isEndOfInput() throws Exception {
135         return !hasNextChunk();
136     }
137 
138     public void close() throws Exception {
139         file.close();
140     }
141 
142     public Object nextChunk() throws Exception {
143         long offset = this.offset;
144         if (offset >= endOffset) {
145             return null;
146         }
147 
148         int chunkSize = (int) Math.min(this.chunkSize, endOffset - offset);
149         byte[] chunk = new byte[chunkSize];
150         file.readFully(chunk);
151         this.offset = offset + chunkSize;
152         return wrappedBuffer(chunk);
153     }
154 }