Getting a HiveServer2 Delegation Token

import java.io.FileWriter;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.security.PrivilegedExceptionAction;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.shims.Utils;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hive.jdbc.HiveConnection;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

public class JDBCTest {
  public static final String driverName = "org.apache.hive.jdbc.HiveDriver";
  public static String connectURL = "jdbc:hive2://node2.cluster0.example.com:2181,node1.cluster0.example.com:2181,node3.cluster0.example.com:2181/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=hiveserver2";
  public static String schemaName = "hcat";
  public static String verticaUser = "condor";
  public static String proxyUser = "condor-2";
  public static String krb5conf = "/home/server/kerberos/krb5.conf";
  public static String realm = "EXAMPLE.COM";
  public static String keytab = "/home/server/kerberos/kt.keytab";

  public static void main(String[] args) {
    if (args.length < 7) {
      System.out.println(
          "Usage: JDBCTest <jdbc_url> <hive_schema> <kerberized_user> <proxy_user> <krb5_conf> <krb_realm> <krb_keytab>");
      System.exit(1);
    }
    connectURL = args[0];
    schemaName = args[1];
    verticaUser = args[2];
    proxyUser = args[3];
    krb5conf = args[4];
    realm = args[5];
    keytab = args[6];

    System.out.println("connectURL: " + connectURL);
    System.out.println("schemaName: " + schemaName);
    System.out.println("verticaUser: " + verticaUser);
    System.out.println("proxyUser: " + proxyUser);
    System.out.println("krb5conf: " + krb5conf);
    System.out.println("realm: " + realm);
    System.out.println("keytab: " + keytab);
    try {
      Class.forName("org.apache.hive.jdbc.HiveDriver");
      System.out.println("Found HiveServer2 JDBC driver");
    } catch (ClassNotFoundException e) {
      System.out.println("Couldn't find HiveServer2 JDBC driver");
    }
    try {
      Configuration conf = new Configuration();
      System.setProperty("java.security.krb5.conf", krb5conf);
      conf.set("hadoop.security.authentication", "kerberos");
      UserGroupInformation.setConfiguration(conf);
      dtTest();
    } catch (Throwable e) {
      Writer stackString = new StringWriter();
      e.printStackTrace(new PrintWriter(stackString));
      System.out.println(e);
      System.out.printf("Error occurred when connecting to HiveServer2 with [%s]: %s\n%s\n",
          new Object[] { connectURL, e.getMessage(), stackString.toString() });
    }
  }

  private static void dtTest() throws Exception {
    UserGroupInformation user = UserGroupInformation.loginUserFromKeytabAndReturnUGI(verticaUser + "@" + realm, keytab);
    user.doAs(new PrivilegedExceptionAction() {
      public Void run() throws Exception {
        System.out.println("In doas: " + UserGroupInformation.getLoginUser());
        Connection con = DriverManager.getConnection(JDBCTest.connectURL);
        System.out.println("Connected to HiveServer2");
        JDBCTest.showUser(con);
        System.out.println("Getting delegation token for user");
        String token = ((HiveConnection) con).getDelegationToken(JDBCTest.proxyUser, "hive/_HOST@" + JDBCTest.realm);
        System.out.println("Got token: " + token);
        System.out.println("Closing original connection");
        con.close();

        System.out.println("Setting delegation token in UGI");
        Utils.setTokenStr(Utils.getUGI(), token, "hiveserver2ClientToken");
        con = DriverManager.getConnection(JDBCTest.connectURL + ";auth=delegationToken");
        System.out.println("Connected to HiveServer2 with delegation token");
        JDBCTest.showUser(con);
        con.close();

        JDBCTest.writeDTJSON(token);

        return null;
      }
    });
  }

  private static void showUser(Connection con) throws Exception {
    String sql = "select current_user()";
    Statement stmt = con.createStatement();
    ResultSet res = stmt.executeQuery(sql);
    StringBuilder result = new StringBuilder();
    while (res.next()) {
      result.append(res.getString(1));
    }
    System.out.println("\tcurrent_user: " + result.toString());
  }

  private static void writeDTJSON(String token) {
    JSONArray arr = new JSONArray();
    JSONObject obj = new JSONObject();
    obj.put("schema", schemaName);
    obj.put("token", token);
    arr.add(obj);
    try {
      FileWriter fileWriter = new FileWriter("hcat_delegation.json");
      fileWriter.write(arr.toJSONString());
      fileWriter.flush();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}