Hive1.2.1

pom:

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>

    <groupId>com.neu.edugroupId>
    <artifactId>UDFartifactId>
    <version>1.0-SNAPSHOTversion>
    <dependencies>
        <dependency>
            <groupId>org.apache.hivegroupId>
            <artifactId>hive-execartifactId>
            <version>1.2.1version>
        dependency>
        <dependency>
            <groupId>org.apache.hadoopgroupId>
            <artifactId>hadoop-clientartifactId>
            <version>2.8.0version>
        dependency>
    dependencies>

project>

1.UDF

参考：https://cwiki.apache.org/confluence/display/Hive/HivePlugins

实现大小写转换

事先创建好people表：

CREATE TABLE `people`(
  `name` string)
ROW FORMAT DELIMITED 
  FIELDS TERMINATED BY '\t' 
  LINES TERMINATED BY '\n' 
WITH SERDEPROPERTIES ( 
  'escape.delim'=' ') 
STORED AS INPUTFORMAT 
  'org.apache.hadoop.mapred.TextInputFormat' 
OUTPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
  'hdfs://172.17.11.85:9000/user/hive/warehouse/people'
TBLPROPERTIES (
  'COLUMN_STATS_ACCURATE'='true', 
  'numFiles'='1', 
  'totalSize'='48', 
  'transient_lastDdlTime'='1498961850')

新建Maven项目，然后新建类：

import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.io.Text;

/**
 * @version 2017/7/2.10:07
 */
public class ULower extends UDF {
    public Text evaluate(final Text s) {
        if (s == null) {
            return null;
        }
        return new Text(s.toString().toLowerCase());
    }
}

之后打包，上传到Linux集群中任何一个地方，

进入hive CLI:

 add jar /root/UDF-1.0-SNAPSHOT.jar;
 list jars;
 create temporary function my_lower as 'ULower';
 select my_lower(name) from people;

删除UDF：DROP FUNCTION [IF EXISTS] function_name;

2.UDAF:

参考：https://cwiki.apache.org/confluence/display/Hive/GenericUDAFCaseStudy

求和

public static enum Mode {  
    PARTIAL1, //从原始数据到部分聚合数据的过程（map阶段），将调用iterate()和terminatePartial()方法。  
    PARTIAL2, //从部分聚合数据到部分聚合数据的过程（map端的combiner阶段），将调用merge() 和terminatePartial()方法。      
    FINAL,    //从部分聚合数据到全部聚合的过程（reduce阶段），将调用merge()和 terminate()方法。  
    COMPLETE  //从原始数据直接到全部聚合的过程（表示只有map，没有reduce，map端直接出结果），将调用merge() 和 terminate()方法。  
};  

getNewAggregationBuffer()：返回存储临时聚合结果的AggregationBuffer对象。
reset(AggregationBuffer agg)：重置聚合结果对象，以支持mapper和reducer的重用。
iterate(AggregationBuffer agg,Object[] parameters)：迭代处理原始数据parameters并保存到agg中。
terminatePartial(AggregationBuffer agg)：以持久化的方式返回agg表示的部分聚合结果，这里的持久化意味着返回值只能Java基础类型、数组、基础类型包装器、Hadoop的Writables、Lists和Maps。
merge(AggregationBuffer agg,Object partial)：合并由partial表示的部分聚合结果到agg中。
terminate(AggregationBuffer agg)：返回最终结果。

Java code

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;

/**
 * @version 2017/7/2.10:43
 */
public class SumUDAF extends AbstractGenericUDAFResolver {
    static final Log LOG = LogFactory.getLog(SumUDAF.class.getName());

    @Override
    public GenericUDAFEvaluator getEvaluator(GenericUDAFParameterInfo info) throws SemanticException {
        return new TotalNumOfLettersEvaluator();
    }

    public static class TotalNumOfLettersEvaluator extends GenericUDAFEvaluator {

        PrimitiveObjectInspector inputOI;
        ObjectInspector outputOI;
        PrimitiveObjectInspector integerOI;

        int total = 0;

        @Override
        public ObjectInspector init(Mode m, ObjectInspector[] parameters)
                throws HiveException {

            assert (parameters.length == 1);
            super.init(m, parameters);

            // init input object inspectors
            if (m == Mode.PARTIAL1 || m == Mode.COMPLETE) {
                inputOI = (PrimitiveObjectInspector) parameters[0];
            } else {
                integerOI = (PrimitiveObjectInspector) parameters[0];
            }

            // init output object inspectors
            outputOI = ObjectInspectorFactory.getReflectionObjectInspector(Integer.class,
                    ObjectInspectorFactory.ObjectInspectorOptions.JAVA);
            return outputOI;

        }

        /**
         * class for storing the current sum of letters
         */
        static class SumBuffer implements AggregationBuffer {
            int sum = 0;

            void add(int num) {
                sum += num;
            }
        }

        @Override
        public AggregationBuffer getNewAggregationBuffer() throws HiveException {
            SumBuffer result = new SumBuffer();
            return result;
        }

        @Override
        public void reset(AggregationBuffer agg) throws HiveException {
            SumBuffer myagg = new SumBuffer();
        }

        @Override
        public void iterate(AggregationBuffer agg, Object[] parameters)
                throws HiveException {
            assert (parameters.length == 1);
            if (parameters[0] != null) {
                SumBuffer myagg = (SumBuffer) agg;
                Object p1 = inputOI.getPrimitiveJavaObject(parameters[0]);
                myagg.add(Integer.parseInt(String.valueOf(p1)));
            }
        }

        @Override
        public Object terminatePartial(AggregationBuffer agg) throws HiveException {
            SumBuffer myagg = (SumBuffer) agg;
            total += myagg.sum;
            return total;
        }

        @Override
        public void merge(AggregationBuffer agg, Object partial)
                throws HiveException {
            if (partial != null) {
                SumBuffer myagg1 = (SumBuffer) agg;
                Integer partialSum = (Integer) integerOI.getPrimitiveJavaObject(partial);
                myagg1.add(partialSum);
            }
        }

        @Override
        public Object terminate(AggregationBuffer agg) throws HiveException {
            SumBuffer myagg = (SumBuffer) agg;
            return myagg.sum;
        }

    }
}

 add jar /root/UDF-1.0-SNAPSHOT.jar;
 CREATE FUNCTION UDSum as 'SumUDAF';
 SELECT  UDSum(money)  FROM salary;
 DROP FUNCTION IF EXISTS UDSum;