hive 中简单的udf函数编写

1.注册函数，使用using jar方式在hdfs上引用udf库。
$hive>create function formattime as ‘com.it18zhang.applogs.udf.FormatTimeUDF‘ using jar ‘hdfs://hadoop01/app/app-logs-hive-1.0-SNAPSHOT.jar‘;2.注销函数，只需要删除mysql的hive数据记录即可。
delete from func_ru ;
delete from funcs ;show funcyions；desc formatted function substring；

2.udf函数获取天开始一些简单方法@Description(name = "udf_getdaybegin",
            value = "getdaybegin",
            extended = "getdaybegin() ;\r\n"
                               + " getdaybegin(2) \r\n"
                               + " getdaybegin(‘2017/06/29 01:02:03‘) \r\n"
                               + " getdaybegin(‘2017/06/29 01:02:03‘,2) \r\n"
                               + " getdaybegin(date_obj) \r\n"
                               + " getdaybegin(date_obj,2)")
    public class DayBeginUDF extends UDF {
        /**
         * 计算现在的起始时刻(毫秒数)
         */
        public long evaluate() throws ParseException {
            return evaluate(new Date());
        }

        /**
         * 指定天偏移量
         */
        public long evaluate(int offset) throws ParseException {
            return evaluate(DateUtil.getDayBeginTime(new Date(), offset));
        }

        /**
         * 计算某天的开始时刻(毫秒数)
         */
        public long evaluate(Date d) throws ParseException {
            return DateUtil.getDayBeginTime(d).getTime();
        }

        /**
         * 计算某天的开始时刻(毫秒数)
         */
        public long evaluate(Date d, int offset) throws ParseException {
            return DateUtil.getDayBeginTime(d, offset).getTime();
        }

        /**
         * 计算某天的起始时刻(毫秒数)
         */
        public long evaluate(String dateStr) throws ParseException {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
            Date d = sdf.parse(dateStr);
            return evaluate(d);
        }

        /**
         * 计算某天的起始时刻(毫秒数)
         */
        public long evaluate(String dateStr, int offset) throws ParseException {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
            Date d = sdf.parse(dateStr);
            return DateUtil.getDayBeginTime(d, offset).getTime();
        }

        /**
         * 计算某天的起始时刻(毫秒数)
         */
        public long evaluate(String dateStr, String fmt) throws ParseException {
            SimpleDateFormat sdf = new SimpleDateFormat(fmt);
            Date d = sdf.parse(dateStr);
            return DateUtil.getDayBeginTime(d).getTime();
        }

        /**
         * 计算某天的起始时刻(毫秒数)
         */
        public long evaluate(String dateStr, String fmt, int offset) throws ParseException {
            SimpleDateFormat sdf = new SimpleDateFormat(fmt);
            Date d = sdf.parse(dateStr);
            return DateUtil.getDayBeginTime(d, offset).getTime();
        }
    }

原文地址：https://www.cnblogs.com/hejunhong/p/10321022.html