尝试创建连接时找不到JDBC驱动程序

Question

Hive JDBC Code throws exception.I tried using Hive 0.13.0,Hive 1.12.1 and Hive 0.12.0.

But, none of these are creating a connection.

package com.cisco.installbase.hiveconnector;

import java.sql.DriverManager;
import java.sql.SQLException;

import org.apache.log4j.Logger;

import java.sql.Connection;

public class CreateConnection {

    private static final Logger LOGGER = Logger.getLogger(CreateConnection.class);

    private static Connection instance = null;
    static final String drivername = "org.apache.hive.jdbc.HiveDriver";

    private CreateConnection() {

        try {
            LOGGER.info("Creating the connection");

            Class.forName(drivername);
            instance = DriverManager.getConnection("jdbc:hive://hddev-c01-edge-02:9083/");
        } catch (ClassNotFoundException e) {
            LOGGER.error("Error occurred to create connection",e);
        } catch (SQLException e) {
            LOGGER.error(e.getMessage());
        } catch (Exception e) {
            LOGGER.error(e.getMessage());
        }
    }

    public static Connection getInstance() {

        LOGGER.info("Connection Instance");
        if (instance == null) {
            instance = (Connection) new CreateConnection();
        }
        return instance;
    }
}

Exception StackTrace:

16/02/11 07:01:46 INFO hiveconnector.CreateConnection: Connection Instance 16/02/11 07:01:46 INFO hiveconnector.CreateConnection: Creating the connection 16/02/11 07:01:46 ERROR hiveconnector.CreateConnection: No suitable driver found for jdbc:hive://hddev-c01-edge-02:9083/ Exception in thread "main" java.lang.ExceptionInInitializerError Caused by: java.lang.ClassCastException: com.cisco.installbase.hiveconnector.Cre ateConnection cannot be cast to java.sql.Connection at com.cisco.installbase.hiveconnector.CreateConnection.getInstance(Crea teConnection.java:39) at com.cisco.installbase.hiveconnector.CommonDBUtilities.(CommonDBUtilities.java:19) at com.cisco.installbase.hiveconnector.MainApp.(MainApp.java:33)

pom.xml

<dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-jdbc</artifactId>
            <version>0.12.0</version>
        </dependency>
        < dependency> <groupId>org.apache.hive</groupId> <artifactId>hive-jdbc</artifactId> 
            <version>1.2.1</version> </dependency>
        <dependency>

Answer 1

You have two problems, the first "No suitable driver found for jdbc:hive://hddev-c01-edge-02:9083/" means that you either have the wrong driver or the wrong URL for the driver that you loaded.

As you load org.apache.hive.jdbc.HiveDriver , you are using the HiveServer2 client , which uses jdbc:hive2://<host>:<port> as the connection string (note the 2 in the url).

For the second problem, please look at the exception:

Exception in thread "main" java.lang.ExceptionInInitializerError Caused by: java.lang.ClassCastException: com.cisco.installbase.hiveconnector.CreateConnection cannot be cast to java.sql.Connection at com.cisco.installbase.hiveconnector.CreateConnection.getInstance(Crea teConnection.java:39)

and your code:

public static Connection getInstance() {
    LOGGER.info("Connection Instance");
    if (instance == null) {
        instance = (Connection) new CreateConnection();
    }
    return instance;
}

You are trying to cast an instance of your own CreateConnection class to a java.sql.Connection , which it isn't. As it stands your code doesn't make a lot of sense: you are 1) initializing a static field in a constructor, and 2) trying to return said class as a java.sql.Connection . As a side note: static, singleton connections to a database are generally a bad idea.

You could fix your code by changing the constructor to a method that returns a Connection , but this will still leave you with the bad idea of having a singleton connection object:

public class CreateConnection {

    private static final Logger LOGGER = Logger.getLogger(CreateConnection.class);

    private static Connection instance = null;
    static final String drivername = "org.apache.hive.jdbc.HiveDriver";

    public static Connection getInstance() {
        LOGGER.info("Connection Instance");
        if (instance == null) {
            instance = createConnection();
        }
        return instance;
    }

    private static Connection createConnection() {
        try {
            LOGGER.info("Creating the connection");

            Class.forName(drivername);
            return DriverManager.getConnection("jdbc:hive2://hddev-c01-edge-02:9083/");
        } catch (ClassNotFoundException e) {
            LOGGER.error("Error occurred to create connection",e);
        } catch (SQLException e) {
            LOGGER.error(e.getMessage());
        } catch (Exception e) {
            LOGGER.error(e.getMessage());
        }
    }
}