註冊函式：

將自定義函式打成jar包，上傳hdfs

$hive>create function formattime as 'com.air.udf.FormatTimeUDF' using jar 'hdfs://mycluster/user/centos/air-hive-1.0-SNAPSHOT.jar'

使用：

$hive>select formattime(datatime,'yyyy/MM/dd') day   from test where datatime>= getDaybegin() and datatime< getDaybegin(1) ;

自定義函式：

1，將long型的時間片格式化成指定日期格式

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
 * 將long型的時間片格式化成指定日期格式
*/
@Description(name = "udf_formattime",
value = "formattime",
extended = "formattime() ;
 
\r\n"
+ " formattime(1234567,'yyyy/MM/01') \r\n"
+ " formattime('1234567','yyyy/MM/dd')")
public class FormatTimeUDF extends UDF {

   /**
    * 格式化時間,long型
*/
public String evaluate(long ms,String fmt) throws ParseException {
      SimpleDateFormat sdf = new SimpleDateFormat(fmt) ;
Date d = new Date();
d.setTime(ms);
 
      return sdf.format(d) ;
}
   /**
    * 格式化時間，string型別
*/
public String evaluate(String ms,String fmt) throws ParseException {
      SimpleDateFormat sdf = new SimpleDateFormat(fmt) ;
Date d = new Date();
d.setTime(Long.parseLong(ms));
      return sdf.format(d) ;
}

   /**
    * 格式化時間，string型別
*/
public String evaluate(long ms ,String fmt , int week) throws ParseException {
      Date d = new Date();
d.setTime(ms);
//周內第一天
Date firstDay = DateUtil.getWeekBeginTime(d) ;
SimpleDateFormat sdf = new SimpleDateFormat(fmt) ;
      return sdf.format(firstDay) ;
}
}

2，得到今天的起始時間：

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import java.text.SimpleDateFormat;
import java.util.Date;
@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{

    /**
     * 計算現在的起始時刻(毫秒數)
     */
public long  evaluate(){
      return DateUtil.getDayBeginTime(new Date()).getTime();
}

    public long  evaluate(Date d){

        return DateUtil.getDayBeginTime(d).getTime();
}

    public long  evaluate(int offset){
        return DateUtil.getDayBeginTime(new Date(),offset).getTime();
}

    public long  evaluate(Date d,int offset){
        return DateUtil.getDayBeginTime(d,offset).getTime();
}

    public  long  evaluate(String dateStr) throws Exception{
        SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date d = df.parse(dateStr);
        return evaluate(d);
}
    public long  evaluate(String dateStr,int offset) throws Exception{
        SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date d = df.parse(dateStr);
        return evaluate(d,offset);
}
    public long  evaluate(String dateStr,String fmt) throws Exception{
        SimpleDateFormat df = new SimpleDateFormat(fmt);
Date d = df.parse(dateStr);
        return evaluate(d);
}
    public long  evaluate(String dateStr,int offset, String fmt) throws Exception{
        SimpleDateFormat df = new SimpleDateFormat(fmt);
Date d = df.parse(dateStr);
        return evaluate(d,offset);
}

    
}

工具類：

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class DateUtil {
   /**
    * 得到指定date的零時刻.
    */
public static Date getDayBeginTime(Date d) {
      try {
         SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd 00:00:00");
         return sdf.parse(sdf.format(d));
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}

   /**
    * 得到指定date的偏移量零時刻.
    */
public static Date getDayBeginTime(Date d,int offset) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
c.add(Calendar.DAY_OF_MONTH,offset);
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}

   /**
    * 得到指定date所在周的起始時刻.
    */
public static Date getWeekBeginTime(Date d) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
         int i = c.get(Calendar.DAY_OF_WEEK);
c.add(Calendar.DAY_OF_MONTH,-(i-1));
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}
   /**
    * 得到指定date所在周的結束時刻.
    */
public static Date getWeekEndTime(Date d) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
         int i = c.get(Calendar.DAY_OF_WEEK);
c.add(Calendar.DAY_OF_MONTH,(8-i));
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}
   /**
    * 得到指定date所在周的結束時刻.
    */
public static Date getWeekEndTime(Date d,int offset) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
         int i = c.get(Calendar.DAY_OF_WEEK);
c.add(Calendar.DAY_OF_MONTH,(8-i));
c.add(Calendar.DAY_OF_MONTH,offset*7);
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}

   /**
    * 得到指定date所在周的起始時刻.
    */
public static Date getWeekBeginTime(Date d,int offset) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
         int i = c.get(Calendar.DAY_OF_WEEK);
c.add(Calendar.DAY_OF_MONTH,-(i-1));
c.add(Calendar.DAY_OF_MONTH,offset*7);
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}
   /**
    * 得到指定date所在月的起始時刻.
    */
public static Date getMonthBeginTime(Date d ) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
         int i = c.get(Calendar.DAY_OF_MONTH);
c.add(Calendar.DAY_OF_MONTH,-(i-1));
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}
   /**
    * 得到指定date所在月的起始時刻.
    */
public static Date getMonthBeginTime(Date d,int offset) {
      try {
         Date date=getDayBeginTime(d);
Calendar c = Calendar.getInstance();
c.setTime(date);
         int i = c.get(Calendar.DAY_OF_MONTH);
c.add(Calendar.DAY_OF_MONTH,-(i-1));
c.add(Calendar.MONTH,offset);
         return c.getTime();
} catch (Exception e) {
         e.printStackTrace();
}
      return null;
}

}