Custom Functions -> UDF
01. Write a function to realize the value of the field attribute case conversion
Add hive file dependencies in pom.xml
<dependency>
<groupId>org.apache.hive</groupId>
<artifactId>hive-jdbc</artifactId>
<version>0.13.1</version>
</dependency>
<dependency>
<groupId>org.apache.hive</groupId>
<artifactId>hive-exec</artifactId>
<version>0.13.1</version>
</dependency>
New ToLowCase class in maven project
package com.darrenzhang.hivedemo.hive_demo;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.io.Text;
public class ToLowCase extends UDF{
public Text evaluate(Text str){
if(str == null) return null;
if(str != null&& str.toString().length() <= 0) return null;
return new Text(str.toString().toLowerCase());
}
public static void main(String[] args){
System.out.println(new ToLowCase().evaluate(new Text(args[0])));
}
}
It is labeled jar package
![17696673-bf1ed1b512ef3e44.png](https://upload-images.jianshu.io/upload_images/17696673-bf1ed1b512ef3e44.png)
Export to jar file
![17696673-7f11f35e56b2c472.png](https://upload-images.jianshu.io/upload_images/17696673-7f11f35e56b2c472.png)
Civilian storage jar package
And then has been next, finish it.
After labeled jar package, jia put this package to a temporary hive list
![17696673-23a4199f5a35ab22.png](https://upload-images.jianshu.io/upload_images/17696673-23a4199f5a35ab22.png)
The jar package posted to the hive a temporary list
![17696673-294c2f007e8daa04.png](https://upload-images.jianshu.io/upload_images/17696673-294c2f007e8daa04.png)
The jar package posted to the hive a temporary list
![17696673-ffa3610936a5e82e.png](https://upload-images.jianshu.io/upload_images/17696673-ffa3610936a5e82e.png)
Whether the query added successfully