Hibernate - ClassNotFoundException： com.mysql.jdbc.Driver

java mysql hibernate jdbc

2022-09-02 05:10:27

我正在尝试通过Hibernate从MySQL数据库中检索数据，但我遇到了这个错误：

Failed to create sessionFactory object.org.hibernate.service.classloading.spi.ClassLoadingException: Specified JDBC Driver com.mysql.jdbc.Driver could not be loaded

java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver
[...]

我使用一个名为 DAOFactory 的类来获取休眠会话：

public class DAOFactory {

    private static boolean isInstance = false;  
    private static SessionFactory sessionFactory;
    private static ServiceRegistry serviceRegistry; 
    private static Session session;

    private DAOFactory() throws ExceptionInInitializerError{        
        if( !isInstance ) {
            try {               
                Configuration cfg   = new Configuration().configure();              
                serviceRegistry     = new ServiceRegistryBuilder().applySettings(cfg.getProperties())
                                                .buildServiceRegistry();
                sessionFactory      = cfg.buildSessionFactory(serviceRegistry);
            } catch (Throwable ex) {
                System.err.println("Failed to create sessionFactory object."+ ex);
                throw new ExceptionInInitializerError(ex);
            }
            session = sessionFactory.openSession();         
            isInstance = true ;
        }               
    }

    public static DAOFactory getInstance() {        
        return new DAOFactory() ;
    }

    public Session getSession() {
        return session ;
    }
}

休眠.cfg.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory name="">
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/enigma</property>
        <property name="connection.username">root</property>
        <property name="connection.password"></property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="connection.pool_size">1</property>
        <property name="current_session_context_class">thread</property>
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
        <property name="show_sql">true</property>
        <property name="hbm2ddl.auto">update</property>
    </session-factory>
</hibernate-configuration>

并且已经在类路径中：mysql-connector-java-5.1.26-bin.jar

classpath

有没有人看到我错过了什么？

答案 1

感谢Reimus的答案。需要位于运行时类路径中。mysql-connector-java-5.1.26-bin.jar

运行 -> 运行配置... ->类路径 -> 添加外部 JAR。

清除所有内容，重试，异常消失。

答案 2

对于那些使用Maven的人：在pom.xml中添加以下依赖项。

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.17</version>
</dependency>

或从此处选择其他版本。

然后，您可以使用以下命令获取工件：

mvn dependency:resolve

（如果不使用 IDE）。