@Override
  public void activateOptions() {
    if (fileName != null) {
      try {
        setFile(fileName, fileAppend, bufferedIO, bufferSize);
      } catch (java.io.IOException e) {
        errorHandler.error("setFile(" + fileName + "," + fileAppend + ") call failed.", e,
          org.apache.log4j.spi.ErrorCode.FILE_OPEN_FAILURE);
      }
    }
  }
If the value of <b>File</b> is not <code>null</code>, then {@link #setFile} is called with the
values of <b>File</b> and <b>Append</b> properties.
@since 0.8.1
hbase-logging/src/test/java/org/apache/log4j/FileAppender.java