void printPeriodicity(int type) {
        switch (type) {
        case TOP_OF_MINUTE:
            LogLog.debug("Appender [" + name + "] to be rolled every minute.");
            break;
        case TOP_OF_HOUR:
            LogLog.debug("Appender [" + name + "] to be rolled on top of every hour.");
            break;
        case HALF_DAY:
            LogLog.debug("Appender [" + name + "] to be rolled at midday and midnight.");
            break;
        case TOP_OF_DAY:
            LogLog.debug("Appender [" + name + "] to be rolled at midnight.");
            break;
        case TOP_OF_WEEK:
            LogLog.debug("Appender [" + name + "] to be rolled at start of week.");
            break;
        case TOP_OF_MONTH:
            LogLog.debug("Appender [" + name + "] to be rolled at start of every month.");
            break;
        default:
            LogLog.warn("Unknown periodicity for appender [" + name + "].");
        }
    }
Returns the value of the <b>DatePattern</b> option.
metamorphosis-client-extension/src/main/java/com/taobao/metamorphosis/client/extension/log4j/DailyRollingFileStreamAppender.java