HIVE UDTF 自定义函数
关键词：HIVE UDTF 开发 实例
Hive运行用户自定义函数对数据信息处理，可以试用show functions查看 hive当前支持的函数，查看凡是如下
hive> show functions
> ;
OK
!
!=
%
&
*
+
-
/
hive支持三种类型的UDF函数：
-
普通UDF函数：
操作单个数据行，且产生一个数据作为输出。例如（数学函数，字符串函数） -
聚合udf （UDAF）
接受多个数据行，并产生一个数据行作为输出。例如（COUNT，MAX函数等） -
表生成UDF(UDTF)
接受一个数据行，然后返回产生多个数据行（一个表作为输出）
UDTF自定义函数的实现：
编码实现：
UDTF函数的实现必须通过继承抽象类GenericUDTF，并且要实现initialize, process,close 函数。
-
initialize实现如下：
package com.jd.risk.hive.UDTF;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDTF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import java.util.ArrayList;
import java.util.List;
public class FeatureParseUDTF extends GenericUDTF {
private PrimitiveObjectInspector stringOI = null;
@Override
public StructObjectInspector initialize(ObjectInspector[] objectInspectors) throws UDFArgumentException {
// 异常检测
if (objectInspectors.length != 1) {
throw new UDFArgumentException("NameParserGenericUDTF() takes exactly one argument");
}
if(objectInspectors[0].getCategory()!=ObjectInspector.Category.PRIMITIVE&&((PrimitiveObjectInspector) objectInspectors[0]).getPrimitiveCategory() != PrimitiveObjectInspector.PrimitiveCategory.STRING) {
throw new UDFArgumentException("NameParserGenericUDTF() takes a string as a parameter");
}
//输入
stringOI = (PrimitiveObjectInspector) objectInspectors[0];
// 输出
List<String> fieldNames = new ArrayList<String>(2);
List<ObjectInspector> fieldOIs = new ArrayList<ObjectInspector>(2);
// 输出列名
fieldNames.add("name");
fieldNames.add("value");
fieldOIs.add(PrimitiveObjectInspectorFactory.javaStringObjectInspector);
fieldOIs.add(PrimitiveObjectInspectorFactory.javaStringObjectInspector);
return ObjectInspectorFactory.getStandardStructObjectInspector(fieldNames, fieldOIs);
}
}
hive将通过initialize方法来获取UDTF函数要求的参数类型然后返回与UDTF函数输出行对象相应的Inspector。initialize使用PrimitiveObjectInspector来解析输入的数据，同时定义输出对象Inspector所需要的field。
-
process实现如下：
@Override
public void process(Object[] record) throws HiveException {
final String feature = stringOI.getPrimitiveJavaObject(record[0]).toString();
ArrayList<Object[]> results = parseInputRecord(feature);
Iterator<Object[]> it = results.iterator();
while (it.hasNext()){
Object[] r= it.next();
forward(r);
}
}
/**
* 解析函数，将json格式字符格式化成多行数据
* @param feature
* @return
*/
public ArrayList<Object[]> parseInputRecord(String feature){
ArrayList<Object[]> resultList = null;
try {
JSONObject json = JSON.parseObject(feature);
resultList = new ArrayList<Object[]>();
for (String nameSpace : json.keySet()) {
JSONObject dimensionJson = json.getJSONObject(nameSpace);
for (String dimensionName : dimensionJson.keySet()) {
JSONObject featureJson = dimensionJson.getJSONObject(dimensionName);
for (String featureName : featureJson.keySet()) {
String property_name = nameSpace + ":" + dimensionName + ":" + featureName;
Object[] item = new Object[2];
item[0] = property_name;
item[1] = featureJson.get(featureName);
resultList.add(item);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return resultList;
}
process函数实现具体的数据解析过程，在通过stringIO获取输入字段，程序中使用parseInputRecord方法将json字符串解析成多个字符，将返回一个List完成一行转多行的任务。最后forward将多行数据做udtf函数的输出。
-
close实现如下：
@Override
public void close() throws HiveException {
}
- maven 依赖：
<?xml version="1.0" encoding="UTF-8"?>
<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>4.0.0</modelVersion>
<groupId>com.jd.udf</groupId>
<artifactId>featureParse</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.apache.hive</groupId>
<artifactId>hive-exec</artifactId>
<version>0.12.0</version>
<scope>provided</scope>
</dependency>
<!-- JSON -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.1.31</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>com.allen.capturewebdata.Main</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
</project>
打包命令：
mvn assembly:assembly
UDTF使用方式：
未使用UDTF函数：
hive> select features from table1 where dt = '2017-07-18'
OK
{"rcm": {"ordering_date": {"feature1": "0","feature2": "1","feature3": "2"}}}
Time taken: 505.014 seconds, Fetched: 1 row(s)
hive>
使用UDTF函数：
hive> select featureParseUDTF(features)from table1 where dt = '2017-07-18'
OK
rcm:ordering_date:feature3 2
rcm:ordering_date:feature2 1
rcm:ordering_date:feature1 0
Time taken: 505.014 seconds, Fetched: 3 row(s)
hive>
加载featureParseUDTF方法：
hive> add jar /home/udtf/featureParse-1.0-SNAPSHOT-jar-with-dependencies.jar
> ;
Added [/home/udtf/featureParse-1.0-SNAPSHOT-jar-with-dependencies.jar] to class path
Added resources: [/home/udtf/featureParse-1.0-SNAPSHOT-jar-with-dependencies.jar]
hive> Create temporary function featureParseUDTF as 'com.jd.risk.hive.UDTF.FeatureParseUDTF';
OK
Time taken: 0.024 seconds
hive> select featureParseUDTF(features)from table1 where dt = '2017-07-18'
OK
rcm:ordering_date:feature3 2
rcm:ordering_date:feature2 1
rcm:ordering_date:feature1 0
Time taken: 505.014 seconds, Fetched: 3 row(s)
参考文献
1、http://beekeeperdata.com/posts/hadoop/2015/07/26/Hive-UDTF-Tutorial.html
2、https://acadgild.com/blog/hive-udtf/
3、http://db3.iteye.com/blog/1072778
