JBDS HHH000319：无法获取数据库元数据：java.sql.SQLException：找不到合适的驱动程序 [重复]

Question

我无法让 web 应用正常工作。 我正在使用 Red Hat JBoss Developer Studio 8.1.0.GA，我在部署时遇到了错误。

java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost:5432/hibernatedb

这是我的 persistence.xml

<persistence-unit name="HibernateProject"
    transaction-type="JTA">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>

    <class>com.test.model.UserDetails</class>
    <properties>
        <property name="hibernate.connection.driver.class" value="org.postgresql.Driver"></property>
        <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
        <property name="hibernate.show_sql" value="true" />
        <property name="hibernate.hbm2ddl.auto" value="validate" />
        <property name="hibernate.connection.url"
            value="jdbc:postgresql://localhost:5432/hibernatedb"></property>
        <property name="hibernate.connection.username" value="postgres"></property>
        <property name="hibernate.connection.password" value="1234"></property>
    </properties>
</persistence-unit>

这是我的 servlet

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    UserDetails user = new UserDetails();
    user.setUserName(request.getParameter("username"));

    //use persistence-unit name from persistence.xml
    EntityManagerFactory entityFactory = Persistence.createEntityManagerFactory("HibernateProject");

    EntityManager entityManager = entityFactory.createEntityManager();

    EntityTransaction entityTransaction = null;

    try{
        entityTransaction = entityManager.getTransaction();
        entityTransaction.begin();
        entityManager.persist(user);
        entityTransaction.commit();
    }catch(RuntimeException re){
        if(entityTransaction.isActive()){
            entityTransaction.rollback();
            throw re;
        }
    }

}

非常感谢！

Answer 1

将此添加到您的 servlet 初始化中：

Class.forName("org.postgresql.Driver");

JDBC 驱动程序在它们的类静态初始化器中自行注册，调用上述会导致类被加载并执行静态初始化。您只需在应用程序启动时调用一次。

另见 Postgre JDBC 文档：https://jdbc.postgresql.org/documentation/head/load.html