this(false);
try {
// Initialize the datasource
if (srcFile != null) {
FileBackedDataSource d = new FileBackedDataSource(srcFile, readOnly);
channel = d.getChannel();
_data = d;
} else {
_data = new FileBackedDataSource(channel, readOnly);
}
// Get the header
ByteBuffer headerBuffer = ByteBuffer.allocate(POIFSConstants.SMALLER_BIG_BLOCK_SIZE);
IOUtils.readFully(channel, headerBuffer);