將科學(xué)計(jì)數(shù)法轉(zhuǎn)成decimal

編寫java

package cn.bdp.udf;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import java.math.BigDecimal;

@Description(name = "number_convert",
        value = "_FUNC_(string) - Convert a string to bigDecimal ，return str.")
public class NumberConvertUDF extends UDF {

    public String evaluate(String str) {
        if (str == null) {
            return "0";
        }
        try {
            BigDecimal bd = new BigDecimal(str);
            String result = bd.toPlainString();
            return result;
        } catch (Exception e) {
            return "0";
        }
    }
}

打包生成my_udf_jar.jar

創(chuàng)建自定義函數(shù)

# 將jar包上傳到HDFS
hive> add jar /tmp/my_udf_jar.jar;

# 將jar包上傳到HDFS
hive> create temporary function number_convert as 'cn.bdp.udf.NumberConvertUDF ';

hive> select number_convert("4.548820080129802E-4");

0.0004548820080129802

hive> select CAST( number_convert("4.548820080129802E-4") AS decimal(9,5) )  ;

0.00045

更新jar包操作

# 列出所有jar
hive> list jars;

# 刪除對(duì)應(yīng)的tmp
hive> delete jar /tmp/448a59e7-5ef8-4b76-8eed-ba04c73e126a_resources/udf-1.0.jar;

hive> DROP TEMPORARY FUNCTION number_convert;