创建hive udf用户自定义函数

一、前提准备

1.搭建idea maven 开发环境
file -->Mew --> project -->Maven-

搭建maven工程

2.配置pom.xml

<dependency>
      <groupId>org.apache.hive</groupId>
      <artifactId>hive-exec</artifactId>
      <version>2.2.0</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-common</artifactId>
      <version>2.6.2</version>
</dependency>

然后导入import maven变更

二、编写一个简单的函数

package com.paic;

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

public final class Lower extends UDF {
    public Text evaluate(final Text s){
        if (s == null){
            return null;
        }
        return new Text(s.toString().toLowerCase());
    }
}

image.png

注意：自定义UDF需要继承UDF类并实现evaluate()函数

1.运行无误后打包
打包：直接在命令行输入: mvn clean package

2.上传到linux服务器/home/udf/
3.进入hive，将jar包导入hive中

hive> add jar /home/udf/Lower.jar ;
Added [/home/udf/Lower.jar] to class path
Added resources: [/home/udf/Lower.jar]
hive> create temporary function testLower as 'com.paic.Lower';
hive> insert into Test values("ZHANZHE");
hive> select testLower(name) from Test;
OK
zhanzhe