package org.apache.mina.filter.stream;
import java.io.IOException;
import org.apache.mina.common.FileRegion;
import org.apache.mina.common.IoBuffer;
import org.apache.mina.common.IoFilter;
import org.apache.mina.common.IoSession;
import org.apache.mina.common.WriteRequest;
/**
* Filter implementation that converts a {@link FileRegion} to {@link IoBuffer}
* objects and writes those buffers to the next filter. When end of the
* {@code FileRegion} has been reached this filter will call
* {@link IoFilter.NextFilter#messageSent(IoSession,WriteRequest)} using the
* original {@link FileRegion} written to the session and notifies
* {@link org.apache.mina.common.WriteFuture} on the original
* {@link org.apache.mina.common.WriteRequest}.
* <p>Normall {@code FileRegion} objects should be handled by the
* {@link org.apache.mina.common.IoProcessor} but this is not always possible
* if a filter is being used that needs to modify the contents of the file
* before sending over the network (i.e. the
* {@link org.apache.mina.filter.ssl.SslFilter} or a data compression filter.)
* </p>
* <p> This filter will ignore written messages which aren't {@link FileRegion}
* instances. Such messages will be passed to the next filter directly.
* </p>
* <p><b>NOTE:</b> this filter does not close the file channel in
* {@link FileRegion#getFileChannel()} after the data from the file has been
* written. The {@code FileChannel} should be closed in either
* {@link org.apache.mina.common.IoHandler#messageSent(IoSession,Object)}
* or in an {@link org.apache.mina.common.IoFutureListener} associated with the
* {@code WriteFuture}.
* </p>
*
* @author The Apache MINA Project (dev@mina.apache.org)
* @version $Rev$, $Date$
*/
public class FileRegionWriteFilter extends
AbstractStreamWriteFilter<FileRegion> {
@Override
protected Class<FileRegion> getMessageClass() {
return FileRegion.class;
}
@Override
protected IoBuffer getNextBuffer(FileRegion fileRegion) throws IOException {
// If there are no more bytes to read, return null
if (fileRegion.getRemainingBytes() <= 0) {
return null;
}
// Allocate the buffer for reading from the file
final int bufferSize = (int) Math.min(getWriteBufferSize(), fileRegion.getRemainingBytes());
IoBuffer buffer = IoBuffer.allocate(bufferSize);
// Read from the file
int bytesRead = fileRegion.getFileChannel().read(buffer.buf(),
fileRegion.getPosition());
fileRegion.update(bytesRead);
// return the buffer
buffer.flip();
return buffer;
}
}