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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 }