fi UDF

UDF写法要求：

·      1.UDF必须继承：org.apache.hadoop.hive.ql.exec.UDF

·      2.必须至少实现一个evaluate方法，支持重载

在hive中添加UDF的方法：

·      将UDF上传到HDFS

·      登录beeline客户端，执行set的语句：set role admin;

·      在hive中注册jar包：add jarhdfs://hacluster/user/hds/udf_jar/UDF_DATE.jar;注意需要写HDFS集群名称如：hdfs://hacluster

·      如果在udf中使用了第三方的Jar包，需要将该jar包一起上传到hdfs,需要进行add jar操作，需注意：被引用的jar包先进性addjar操作，即引用jar包有先后顺序

·      创建函数 :TEMPORARY  表示此函数只是当前session生效

       CREATE TEMPORARY FUNCTION udf_date AS'com.huawei.bigdata.hive.example.UDF_DATE';

UDF_demo:

packagecom.huawei.bigdata.hive.example;

importjava.text.SimpleDateFormat;

importjava.util.Calendar;

importjava.util.Date;

importorg.apache.hadoop.hive.ql.exec.UDF;

/**

 * 做日期的加减运算

 *

 *@authorAdministrator

 *input_date：输入的日期

 *flag1:计算的频度 Y代表年 M代表月 D代表天

 *values：日期前后移动的位数

 */

publicclassUDF_DATEextendsUDF {

     publicStringevaluate(String input_date, String flag1, String values) {

     

           // 判断输入的日期是否合法

           if(input_date.length()!= 10 && input_date.length() != 8) {

                System.out.println("input_dateis wrong ,pleas check again ");

                System.exit(1);

           }

           if(!flag1.toUpperCase().equals("Y")

                     &&!flag1.toUpperCase().equals("M")

                     &&!flag1.toUpperCase().equals("D")) {

                System.out.println("flag1is wrong ,pleas check again ");

                System.out.println("please input Y or M  or D");

                System.exit(1);

           }

           // 判断输入的天数运算的值是否为数字

           booleanflag11 =true;

           for(inti =values.length(); --i > 0;) {

                if(!Character.isDigit(values.charAt(i))){

                     flag11=false;

                }

           }

           if(flag11 !=true) {

                System.out.println("flag2is values ,pleas check again ");

                System.exit(1);

           }

           Calendarcal = Calendar.getInstance();

           // 时间标准化

           SimpleDateFormatdf1 =newSimpleDateFormat("yyyyMMdd");

           SimpleDateFormatdf2 =newSimpleDateFormat("yyyy-MM-dd");

           // 判断日期的位数

           Stringoutput_date =null;

           if(input_date.length()== 10) {

           try{

                Dateinitdate=df2.parse(input_date);

                System.out.println(df2.format(initdate));

                cal.setTime(initdate);

                if(flag1.toUpperCase().equals("Y")) {

                     cal.add(Calendar.YEAR, Integer.parseInt(values));

                     output_date= df2.format(cal.getTime());

                }elseif(flag1.toUpperCase().equals("M")) {

                     cal.add(Calendar.MONTH, Integer.parseInt(values));

                     output_date= df2.format(cal.getTime());

                }elseif(flag1.toUpperCase().equals("D")) {

                     cal.add(Calendar.DATE, Integer.parseInt(values));

                     output_date= df2.format(cal.getTime());

                }

           }catch(Exception e) {

                e.printStackTrace();

           }

           }else{

                try{

                     Dateinitdate=df1.parse(input_date);

                     System.out.println(df1.format(initdate));

                     cal.setTime(initdate);

                     if(flag1.toUpperCase().equals("Y")) {

                           cal.add(Calendar.YEAR, Integer.parseInt(values));

                           output_date= df1.format(cal.getTime());

                     }elseif(flag1.toUpperCase().equals("M")) {

                           cal.add(Calendar.MONTH, Integer.parseInt(values));

                           output_date= df1.format(cal.getTime());

                     }elseif(flag1.toUpperCase().equals("D")) {

                           cal.add(Calendar.DATE, Integer.parseInt(values));

                           output_date= df1.format(cal.getTime());

                     }

                }catch(Exception e) {

                     e.printStackTrace();

                }

           }

           returnoutput_date;

     }                        

}