我知道已经有类似的问题,但是那里的答案并没有帮助我。因此,请介意查看我的特定问题吗?
我对Hibernate的使用还不是很熟练,并且在尝试使用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,我以完全相同的方式进行操作,并且在那里工作,因此我进行了完全相同的设置,但使用了另一个数据库,但是现在在我的当前项目中,我得到以下异常:
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
我搜索了可能的解决方案,但没有一个对我有用:
-)在Manifest.mf中指定jar的类路径->不起作用-)将postgresql-9.4.1208.jre6.jar放在WEB-INF下的lib文件夹中->不起作用-)在以下位置指定hibernate.cfg.xml文件Configuration()。configure(); ->没有用
我使用Glassfish 4.1,并且存在org.postgres.Driver.class,所以为什么找不到它?
我的hibernate.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> <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property> <property name="hibernate.connection.driver_class">org.postgresql.Driver</property> <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/Testdb</property> <property name="hibernate.connection.username">username</property> <property name="hibernate.hbm2ddl.auto">create-drop</property> <property name="hibernate.connection.password">password</property> <mapping class="entity.Benutzer"/> </session-factory> </hibernate-configuration>
DAO类中发生异常的方法:
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); }
我会很感激每一个答案。
你近了!
您需要postgresql-<version>.jar直接将其放置在 servlet容器* 的lib文件夹中。 例如,如果您使用的是_Apache Tomcat_ ,只需将 jar放到 下面,就应该准备就绪。 * <TOMCAT_ROOT>/lib
postgresql-<version>.jar
lib
<TOMCAT_ROOT>/lib