import org.apache.hadoop.security.UserGroupInformation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.security.PrivilegedAction;
import java.sql.*;
import java.util.LinkedList;

/*** 类名： ImpalaJdbcUtils

• • 描述：impala jdbc的工具类
• • 自定义连接工具池
• • /
    public class ImpalaJdbcUtils {
    private static final Logger log = LoggerFactory.getLogger(ImpalaJdbcUtils.class);
    /* 描述：驱动类
    */
    private static String DRIVER_CLASS = "org.apache.hive.jdbc.HiveDriver";
    private static String CONNECTION_URL = "jdbc:hive2:///default;principal=impala/";
    / 连接池/
    private static LinkedList pool = new LinkedList();//初始化10个连接

  static {
  try {
  for (int i = 0; i < 15; i++) {
  Connection conn = getImpalaConnection();
  //得到一个连接
  pool.add(conn);
  }
  } catch (Exception e) {
  log.error("数据库连接池初始化失败，请检查配置", e);
  }
  }
  /*** 从连接池中获取连接**/
  public static Connection getConnection() throws SQLException {
  // 取出连接池中一个连接
  Connection conn = null;
  // 测试连接是否超时，超时重新连接
  try {
  conn = pool.removeFirst();
  //执行以下链接，查看是否异常
  String sql = "show DATABASES";
  PreparedStatement ps = conn.prepareStatement(sql);
  ResultSet rs = ps.executeQuery();
  rs.close();
  ps.close();
  }catch (Exception e){
  log.warn("连接异常,尝试重新生成连接！");
  conn = getImpalaConnection();
  }
  // 删除第一个连接返回
  log.info("取出一个连接剩余 " + pool.size() + "个连接！");
  return conn;
  }

  /*** @Description 释放连接***/
  public static void releaseConnection(Connection conn) {
  pool.add(conn);
  log.info("将连接放回到连接池中,数量:" + pool.size());
  }
  /*** @Description 获取impala连接* /
  public static Connection getImpalaConnection() {
  try {
  Object o = UserGroupInformation.getLoginUser().doAs((PrivilegedAction) () -> {
  Connection connection = null;
  try {
  Class.forName(DRIVER_CLASS);
  } catch (ClassNotFoundException e) {
  log.error("加载impala驱动失败", e);
  }
  try {
  connection = DriverManager.getConnection(CONNECTION_URL);
  } catch (SQLException e) {
  log.error("获取jdbc连接失败", e);
  }
  return connection;
  });
  return (Connection) o;
  } catch (IOException e) {
  e.printStackTrace();
  }
  return null;
  }
  /* 关闭jdbc连接* **/
  public static void disconnect(Connection connection, ResultSet res, PreparedStatement ps) {
  try {
  if (res != null){
  res.close();
  }
  if (ps != null){
  ps.close();
  }
  if (connection != null) {
  connection.close();
  ImpalaJdbcUtils.releaseConnection(connection);
  }
  } catch (SQLException e) {
  log.error("jdbc连接关闭失败", e);
  }
  }

  //不使用连接池
  public Connection getConnectSync(){
  try {
  Object o = UserGroupInformation.getLoginUser().doAs((PrivilegedAction) () -> {
  Connection connection = null;
  try {
  Class.forName(DRIVER_CLASS);
  } catch (ClassNotFoundException e) {
  log.error("加载impala驱动失败", e);
  }
  try {
  connection = DriverManager.getConnection(CONNECTION_URL);
  } catch (SQLException e) {
  log.error("获取jdbc连接失败", e);
  }
  return connection;
  });
  return (Connection) o;
  } catch (IOException e) {
  e.printStackTrace();
  }
  return null;
  }
  }