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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.filter.stream;
    21
    22  import java.io.IOException;
    23
    24  import org.apache.mina.core.buffer.IoBuffer;
    25  import org.apache.mina.core.file.FileRegion;
    26
    27  /**
    28   * Filter implementation that converts a {@link FileRegion} to {@link IoBuffer}
    29   * objects and writes those buffers to the next filter. When end of the
    30   * {@code FileRegion} has been reached this filter will call
    31   * {@link IoFilter.NextFilter#messageSent(IoSession,WriteRequest)} using the
    32   * original {@link FileRegion} written to the session and notifies
    33   * {@link org.apache.mina.core.future.WriteFuture} on the original
    34   * {@link org.apache.mina.core.write.WriteRequest}.
    35   * <p>Normall {@code FileRegion} objects should be handled by the
    36   * {@link org.apache.mina.core.service.IoProcessor} but this is not always possible
    37   * if a filter is being used that needs to modify the contents of the file
    38   * before sending over the network (i.e. the
    39   * {@link org.apache.mina.filter.ssl.SslFilter} or a data compression filter.)
    40   * </p>
    41   * <p> This filter will ignore written messages which aren't {@link FileRegion}
    42   * instances. Such messages will be passed to the next filter directly.
    43   * </p>
    44   * <p><b>NOTE:</b> this filter does not close the file channel in
    45   * {@link FileRegion#getFileChannel()} after the data from the file has been
    46   * written.  The {@code FileChannel} should be closed in either
    47   * {@link org.apache.mina.core.service.IoHandler#messageSent(IoSession,Object)}
    48   * or in an {@link org.apache.mina.core.future.IoFutureListener} associated with the
    49   * {@code WriteFuture}.
    50   * </p>
    51   *
    52   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
    53   * @org.apache.xbean.XBean
    54   */
    55  public class FileRegionWriteFilter extends AbstractStreamWriteFilter<FileRegion> {
    56
    57      @Override
    58      protected Class<FileRegion> getMessageClass() {
    59          return FileRegion.class;
    60      }
    61
    62      @Override
    63      protected IoBuffer getNextBuffer(FileRegion fileRegion) throws IOException {
    64          // If there are no more bytes to read, return null
    65          if (fileRegion.getRemainingBytes() <= 0) {
    66              return null;
    67          }
    68
    69          // Allocate the buffer for reading from the file
    70          final int bufferSize = (int) Math.min(getWriteBufferSize(), fileRegion.getRemainingBytes());
    71          IoBuffer buffer = IoBuffer.allocate(bufferSize);
    72
    73          // Read from the file
    74          int bytesRead = fileRegion.getFileChannel().read(buffer.buf(), fileRegion.getPosition());
    75          fileRegion.update(bytesRead);
    76
    77          // return the buffer
    78          buffer.flip();
    79          return buffer;
    80      }
    81
    82  }