自定义 UDF

最新推荐文章于 2024-11-19 15:58:54 发布

原创最新推荐文章于 2024-11-19 15:58:54 发布 · 386 阅读

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本文介绍了一个Hive自定义函数(UDF)的实现过程，该函数用于将输入的日期转换为对应的季节编号。文章详细展示了如何定义和使用QuarterUDF类来解析日期并确定其所属季度，并提供了所需的Maven依赖项以及如何使用shade插件进行编译打包。

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1.所需依赖

        <dependencies>
            <dependency>
                <groupId>org.apache.hive</groupId>
                <artifactId>hive-exec</artifactId>
                <version>0.13.0</version>
            </dependency>
            <dependency>
                <groupId>org.apache.hadoop</groupId>
                <artifactId>hadoop-common</artifactId>
                <version>2.5.0</version>
            </dependency>
        </dependencies>

2.算出时间所属季节
类中需定义evaluate函数

package com.ht.hive;

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

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

/**
 * Created by pan on 2017/9/1.
 */
public class QuarterUDF extends UDF {


    private SimpleDateFormat sdf;
    public QuarterUDF() {

            this.sdf = new SimpleDateFormat("yyyy-MM-dd");
    }

    /**
     *
     * 1 第一季度 2 第二季度 3 第三季度 4 第四季度
     *
     * @param date
     * @return
     */
    public static int getSeason(Date date) {

        int season = 0;

        Calendar c = Calendar.getInstance();
        c.setTime(date);
        int month = c.get(Calendar.MONTH);
        switch (month) {
            case Calendar.JANUARY:
            case Calendar.FEBRUARY:
            case Calendar.MARCH:
                season = 1;
                break;
            case Calendar.APRIL:
            case Calendar.MAY:
            case Calendar.JUNE:
                season = 2;
                break;
            case Calendar.JULY:
            case Calendar.AUGUST:
            case Calendar.SEPTEMBER:
                season = 3;
                break;
            case Calendar.OCTOBER:
            case Calendar.NOVEMBER:
            case Calendar.DECEMBER:
                season = 4;
                break;
            default:
                break;
        }
        return season;
    }

   public String evaluate(String sdate) throws ParseException {


       Date date = sdf.parse(sdate);
       return String.valueOf(getSeason(date));
   }
}

3.shade插件编译打包

  <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.2</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>