首先pom文件导入依赖，Hadoop和hive的依赖导入自己机器的版本，hive记得导jdbc

org.apache.hadoop hadoop-client 2.6.
org.apache.hive hive-service 1.2.
org.apache.hive hive-jdbc 1.2.
org.apache.hive hive-exec 1.2.

新建UDF的Java类

package com.hive.udf;

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

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
* Created by lenovo on 2017/10/26.
*/
public class DateTransforUDF extends UDF{

public static final SimpleDateFormat inputFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  //匹配讲要格式化的日期格式  
public static final SimpleDateFormat outputFormat=new SimpleDateFormat("yyyyMMddHHmmss");  //要格式化的最终格式  
/\*  
2013-02-17 10:38:34  
20130217103834  
 \*/

public Text evaluate(final Text input){  
    Text output=new Text();

    if (null==input){  
        return null;  
    }  
    String inputDate = input.toString().trim();  
    if(null==inputDate){  
        return null;  
    }  
    try {  
        Date parseDate = inputFormat.parse(inputDate);  
        String outputDate = outputFormat.format(parseDate);  
        output.set(outputDate);  
    } catch (ParseException e) {  
        e.printStackTrace();  
        return output;  
    }  
    return output;  
}

public static void main(String\[\] args) {  
    System.out.println(new DateTransforUDF().evaluate(new Text("2013-02-17 10:38:34")));  
}  

}

打jar包，上传到Linux，

hive (register_info)> add jar /root/hive_udf/BaseTest-1.0-SNAPSHOT.jar
> ;
Added [/root/hive_udf/BaseTest-1.0-SNAPSHOT.jar] to class path
Added resources: [/root/hive_udf/BaseTest-1.0-SNAPSHOT.jar]
hive (register_info)> create temporary function Tdate as 'com.test.OnlyDateUDF';
OK
Time taken: 0.006 seconds