用java代码编写，继承UDF类即可

然后打包，导入hive中，再创建个函数名就能使用

hive: add jar '/路径/xxx.jar';
hive: create function 函数名 as '主类名';

以下用计算地球间两点的距离的为例

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

public class CalculateLength extends UDF {
    /**
     * 地球半径
     */
    private static final double EARTH_RADIUS = 6378137;

    /**
     * 计算两个经纬度之间的距离
     *
     * @param longi1 经度1
     * @param lati1  纬度1
     * @param longi2 经度2
     * @param lati2  纬度2
     * @return 距离
     */
    public double evaluate(double longi1, double lati1, double longi2, double lati2) {
        double lat21 = lati1 * Math.PI / 180.0;
        double lat22 = lati2 * Math.PI / 180.0;
        double a = lat21 - lat22;
        double b = (longi1 - longi2) * Math.PI / 180.0;
        double sa2 = Math.sin(a / 2.0);
        double sb2 = Math.sin(b / 2.0);
        double d = 2 * EARTH_RADIUS * Math.asin(Math.sqrt(sa2 * sa2 + Math.cos(lat21) * Math.cos(lat22) * sb2 * sb2));
        return Math.abs(d);
    }
}