未找到指定的 JDBC 驱动程序 com.mysql.jdbc.Driver 类

Question

I am using eclipse juno and hibernate 4.1.6 , mysql connector 5.1.24 , jboss 7.1.1 .

I tried this and this (as a module).

I have the connector JAR in WEB-INF/lib folder, and I also tried once without it. Everything failed. I don't know anymore how I can solve this problem. The whole stack trace:

18:35:44,284 ERROR [stderr] (http-localhost-127.0.0.1-8080-1) Error creating Session: org.hibernate.service.classloading.spi.ClassLoadingException: Specified JDBC Driver com.mysql.jdbc.Driver class not found

The connector is an the class path, it's in the Maven Dependencies Library. I put it in the lib folder and in the System Library...nothing works.

public class HibernateUtil {

private static SessionFactory sessionFactory;
private static ServiceRegistry serviceRegistry;

static
{
    try
    {
        Configuration configuration = new Configuration().configure("hibernate.cfg.xml");
        serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
        sessionFactory = configuration.buildSessionFactory(serviceRegistry);
    }
    catch (HibernateException he)
    {
        System.err.println("Error creating Session: " + he);
        throw new ExceptionInInitializerError(he);
    }
}

Answer 1

Check in your hibernate.cfg.xml file that you have correctly specified the driver class and the dialect :

<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>

(these are properties of the <session-factory> )

Then, simply build your Session Factory:

sessionFactory = new Configuration().configure().buildSessionFactory();

If the application still does not see your Maven dependency for the connector, try doing a clean install, and after it check in the list of libraries for your project that the MySQL Connector appears there.

Answer 2

Please check your mysql connector version is compatible with mysql db installed on your system. eg mysql connector version 5.1.26 is compatible with mysql 5.6.25 while 5.1.34 is not.

Answer 3

尝试将连接器添加到构建路径作为外部 jar 或，创建一个 lib 文件夹并将连接器 jar 放入其中，然后Add Library到您的构建路径并提供该连接器 lib 文件夹路径。

Answer 4

Configuration configuration = new Configuration();
configuration.configure();
ServiceRegistryBuilder serviceRegistryBuilder = new ServiceRegistryBuilder().applySettings(configuration.getProperties());
sessionFactory = configuration.buildSessionFactory(serviceRegistryBuilder.buildServiceRegistry());
// end of static block

public static SessionFactory getSessionFactory() {
    return sessionFactory;
}