1.注册函数，使用using jar方式在hdfs上引用udf库。
$hive>create function formattime as 'com.bigdata.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();
}
}