hive-讓我們一起自定義udf

1.準備編寫udf環境

引入依賴

<dependencies>

              <dependency>

                     <groupId>jdk.tools</groupId>

                     <artifactId>jdk.tools</artifactId>

                     <version>1.8</version>

                     <scope>system</scope>

                     <systemPath>${JAVA_HOME}/lib/tools.jar</systemPath>

              </dependency>

              <!--  https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-common -->

              <dependency>

                     <groupId>org.apache.hadoop</groupId>

                     <artifactId>hadoop-common</artifactId>

                     <version>3.1.3</version>

              </dependency>

              <dependency>

                     <groupId>org.apache.hive</groupId>

                     <artifactId>hive-exec</artifactId>

                     <version>3.1.2</version>

              </dependency>

       </dependencies>

2.編寫udf,繼承UDF,實現evaluate方法

package bigdata.hive;

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

public class UdfDemo extends UDF{

       public String evaluate(String ip){

        String[] datas = ip.split("\\.");//按.切分轉義

        StringBuffer sb = new StringBuffer();

        //前邊補三個0

        for(String s:datas){

            s="000"+s;

            s=s.substring(s.length()-3);

            sb.append(s).append(".");

        }

        return sb.substring(0,sb.length()-1);

    }

//本地測試

    public static void main(String[] args) {

       UdfDemo udfDemo = new UdfDemo();

        String evaluate =udfDemo.evaluate("2.3.5.3");

        System.out.println(evaluate);

    }

}

3.打包udf

執行 maven install命令  進行打包，執行成功出現 ，如下圖

          

4.上傳udf jar 包到 hdfs

hdfs dfs -put bigdata-0.0.1-SNAPSHOT.jar /user/hive/hiveFunction/

5.啓動 hive  創建註冊udf函數

create function UdfDemo as 'bigdata.hive.UdfDemo' using jar 'hdfs://master:9000/user/hive/hiveFunction/bigdata-0.0.1-SNAPSHOT.jar';

6.使用udf函數

測試 udf

select UdfDemo("2.3.5.3");