初始SessionFactory创建failed.org.hibernate.exception.JDBCConnectionException：调用Driver＃connect时出错

Question

我正在尝试将MYSQL与Hibernate一起使用，但在使用hibernate连接到MYSQL数据库时遇到问题。

以下是我遵循的步骤：

我在MYSQL命令下运行：

CREATE DATABASE hibernate5;
USE hibernate5;
GRANT ALL PRIVILEGES ON hibernate5.* To 'hib5'@'localhost' IDENTIFIED BY 'hib';

现在我已经创建了我的hibernate.cfg.xml文件，如下所示：

<session-factory>

    <!-- Database connection settings -->
    <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="connection.url">jdbc:mysql://localhost:3306/hibernate5</property>
    <property name="connection.username">hib5</property>
    <property name="connection.password">hib</property>

    <!-- JDBC connection pool (use the built-in) -->
    <property name="connection.pool_size">1</property>

    <!-- SQL dialect -->
    <property name="dialect">org.hibernate.dialect.MYSQLDialect</property>

    <!-- Enable Hibernate's automatic session context management -->
    <property name="current_session_context_class">thread</property>

    <!-- Disable the second-level cache -->
    <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

    <!-- Echo all executed SQL to stdout -->
    <property name="show_sql">true</property>

    <!-- Drop and re-create the database schema on startup -->
    <property name="hbm2ddl.auto">create</property>

    <mapping class="org.hibernate.tutorials.Customer" />
</session-factory>

现在我编写了一个简单的程序来检查Hibernate是否能够在MYSQL数据库中创建表：

public class AppTest {
    public static void main(String[] args) {
        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        HibernateUtil.getSessionFactory().close();
    }
}

public class HibernateUtil {

    private static final SessionFactory sessionFactory = buildSessionFactory();

    private static SessionFactory buildSessionFactory() {
        try {
            Configuration configuration = new Configuration();
            configuration.configure("hibernate.cfg.xml");
            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                    .applySettings(configuration.getProperties()).build();
            SessionFactory sessionFactory = configuration
                    .buildSessionFactory(serviceRegistry);
            return sessionFactory;
        } catch (Throwable ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

}

现在，当我运行AppTest.java程序时，我收到的错误是：

Initial SessionFactory creation failed.org.hibernate.exception.JDBCConnectionException: Error calling Driver#connect
Exception in thread "main" java.lang.ExceptionInInitializerError
    at org.hibernate.tutorial.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:32)
    at org.hibernate.tutorial.util.HibernateUtil.<clinit>(HibernateUtil.java:10)
    at org.hibernate.tutorials.one.AppTest.main(AppTest.java:8)
Caused by: org.hibernate.exception.JDBCConnectionException: Error calling Driver#connect
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:132)
    at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator$1$1.convert(BasicConnectionCreator.java:118)
    at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.convertSqlException(BasicConnectionCreator.java:140)
    at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:58)
    at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.createConnection(BasicConnectionCreator.java:75)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:106)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.buildJdbcConnectionAccess(JdbcServicesImpl.java:260)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:94)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
    at org.hibernate.tutorial.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:27)
    ... 2 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:408)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1137)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:356)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2504)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2541)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2323)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:408)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
    at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:55)
    ... 15 more
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
    at java.net.Socket.connect(Socket.java:529)
    at java.net.Socket.connect(Socket.java:478)
    at java.net.Socket.<init>(Socket.java:375)
    at java.net.Socket.<init>(Socket.java:218)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:258)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:306)
    ... 28 more

请帮助我在哪里犯错？

我使用命令SHOW VARIABLES登录MYSQL并检查主机和端口的变量，端口号是否正确并设置为默认值（3306），我使用了变量中提到的主机名，但即便如此我也是面临同样的问题。我可以在任何问题的命令提示符下运行MYSQL。

更新： 我还使用以下命令为新创建的用户授予了权限：

grant usage on *.* to hib5@localhost identified by 'hib'; 
grant all privileges on hibernate5.* to hib5@localhost;