1、UDF中如何读取Hive的表数据，这个可以做到吗？

[AnselJoker]

package com.inspur.udf;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.security.UserGroupInformation;

public class start_prior {

    public static String evaluate(String table, String column, String column_sj, String para) throws ClassNotFoundException {
        boolean check_re = true;
        StringBuilder sb = new StringBuilder();
        StringBuilder sb_tmp = new StringBuilder();
        sb.append(para);

        String driverName="org.apache.hive.jdbc.HiveDriver";
        String url = "jdbc:hive2://10.111.30.41:10000/default;principal=hive/[e-mail]";

        Configuration conf = new Configuration();
        conf.set("hadoop.security.authentication", "Kerberos");

        try {
            System.setProperty("java.security.krb5.conf", "D:\\workspace\\UDF-MD5\\src\\main\\kerberos\\krb5.conf");
            UserGroupInformation.setConfiguration(conf);
            UserGroupInformation.loginUserFromKeytab("hive/[e-mail]", "D:\\workspace\\UDF-MD5\\src\\main\\kerberos\\hive.service.keytab");
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            Class.forName(driverName);
            Connection conn = DriverManager.getConnection(url);
            PreparedStatement stmt = null;
            ResultSet resultSet = null;

            do{
                String sql = "select " + column + " from " + table + " where " + column_sj + " in (" + para + ")";
                System.out.println(sql);
                stmt = conn.prepareStatement(sql);
                resultSet = stmt.executeQuery();

                if (resultSet.next()){
                    do{
                        sb_tmp.append(resultSet.getString(1) + ",");
                        sb.append("," + resultSet.getString(1));
                    }while(resultSet.next());
                    para=sb_tmp.deleteCharAt(sb_tmp.length()-1).toString();
                    sb_tmp.delete(0,sb_tmp.length());
                }else {
                    check_re=false;
                }

            }while (check_re);

            resultSet.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }
}