Java Hibernate:PostgreSQL驱动程序问题

我知道已经有类似的问题了，但答案对我没有帮助。所以请你看看我的问题好吗

我对Hibernate还不是很有经验，在尝试使用Hibernate 4.3和PostgreSQL为本地数据库创建测试数据时遇到了一个问题

我有另一个项目，我用完全相同的方法进行了这项工作，它在那里工作，所以我做了完全相同的设置，但使用了另一个数据库，但现在在我当前的项目中，我得到了以下例外：

exception.DBException: Could not configure Hibernate!
    at dao.BenutzerDAO.<init>(BenutzerDAO.java:48)
    at export.ExportDBSchema.main(ExportDBSchema.java:16)
Caused by: org.hibernate.boot.registry.classloading.spi.ClassLoadingException: Unable to load class [org.postgresql.Driver]
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:245)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.loadDriverIfPossible(DriverManagerConnectionProviderImpl.java:200)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildCreator(DriverManagerConnectionProviderImpl.java:156)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:95)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:89)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
    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:89)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
    at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
    at dao.BenutzerDAO.<init>(BenutzerDAO.java:45)
    ... 1 more
Caused by: java.lang.ClassNotFoundException: Could not load requested class : org.postgresql.Driver
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl$AggregatedClassLoader.findClass(ClassLoaderServiceImpl.java:230)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:340)
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:242)
    ... 15 more

我将非常感谢你的每一个回答。

你很接近

您需要将

postgresql-.jar

直接放在servlet容器的

lib

文件夹中

---

例如，如果您正在使用ApacheTomcat，只需将您的jar放在

/lib

下，您就应该准备好了。

如果您正在使用maven或gradle

您可以将其添加到maven的ur pom.xml中

<!-- https://mvnrepository.com/artifact/org.postgresql/postgresql -->
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.2.4</version>
</dependency>

---

谢谢你的回答。不幸的是，它仍然抛出异常java.lang.ClassNotFoundException:无法加载请求的类：org.postgresql.Driver。我试着把jar放在我在project和server文件夹中找到的每个lib文件夹中，但都不起作用，同时问题也得到了解决。它与罐子的位置有关，但我不知道这次我做了什么不同，但现在它起作用了：）再次感谢。

try {
            if (sessionFactory == null) {
                Configuration conf = new Configuration().configure();

                StandardServiceRegistryBuilder builder
                        = new StandardServiceRegistryBuilder();
                builder.applySettings(conf.getProperties());

                sessionFactory = conf.buildSessionFactory(builder.build());
            }
        } catch (Throwable ex) {
            throw new DBException("Could not configure Hibernate!", ex);
        }

<!-- https://mvnrepository.com/artifact/org.postgresql/postgresql -->
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.2.4</version>
</dependency>

// https://mvnrepository.com/artifact/org.postgresql/postgresql
compile group: 'org.postgresql', name: 'postgresql', version: '42.2.4'