@Override
  public CharSequence flatten(long timeMillis, int logLevel, String tag, String message) {
    return Long.toString(timeMillis)
        + '|' + LogLevel.getShortLevelName(logLevel)
        + '|' + tag
        + '|' + message;
  }
Simply join the timestamp, log level, tag and message together.

@since 1.3.0
xlog/src/main/java/com/elvishew/xlog/flattener/DefaultFlattener.java