NettyTransport.java 文件源码

void sendFile(File file) throws Exception {
  long length = file.length();
  LOG.debug("Got request of sending file {} of length {}.",
            file, length);
  Message handshake = MessageBuilder.buildFileHeader(length);
  byte[] bytes = handshake.toByteArray();
  // Sends HANDSHAKE first before transferring actual file data, the
  // HANDSHAKE will tell the peer's channel to prepare for the file
  // transferring.
  channel.writeAndFlush(Unpooled.wrappedBuffer(bytes)).sync();
  ChannelHandler prepender = channel.pipeline().get("frameEncoder");
  // Removes length prepender, we don't need this handler for file
  // transferring.
  channel.pipeline().remove(prepender);
  // Adds ChunkedWriteHandler for file transferring.
  ChannelHandler cwh = new ChunkedWriteHandler();
  channel.pipeline().addLast(cwh);
  // Begins file transferring.
  RandomAccessFile raf = new RandomAccessFile(file, "r");
  if (channel.pipeline().get(SslHandler.class) != null) {
    // Zero-Copy file transferring is not supported for ssl.
    channel.writeAndFlush(new ChunkedFile(raf, 0, length, 8912));
  } else {
    // Use Zero-Copy file transferring in non-ssl mode.
    FileRegion region = new DefaultFileRegion(raf.getChannel(), 0, length);
    channel.writeAndFlush(region);
  }
  // Restores pipeline to original state.
  channel.pipeline().remove(cwh);
  channel.pipeline().addLast("frameEncoder", prepender);
}