我最近使用了JPA（带有休眠功能）添加了一些功能（将数据库表连接到其他表）。以前效果不错，但现在我遇到了异常org.hibernate.boot.registry.classloading.spi.ClassLoadingException: Unable to load class []-至少我认为这是最相关的部分。整个例外是：
org.apache.tapestry5.ioc.internal.OperationException:
org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
at org.apache.tapestry5.ioc.internal.OperationTrackerImpl.logAndRethrow(OperationTrackerImpl.java:186)
at org.apache.tapestry5.ioc.internal.OperationTrackerImpl.run(OperationTrackerImpl.java:62)
at org.apache.tapestry5.ioc.internal.PerThreadOperationTracker.run(PerThreadOperationTracker.java:60)
at org.apache.tapestry5.ioc.internal.RegistryImpl.run(RegistryImpl.java:1254)
at org.apache.tapestry5.ioc.internal.StartupDefImpl.invoke(StartupDefImpl.java:48)
at org.apache.tapestry5.ioc.internal.RegistryImpl$2.run(RegistryImpl.java:230)
at org.apache.tapestry5.ioc.internal.RegistryImpl.performRegistryStartup(RegistryImpl.java:361)
at org.apache.tapestry5.ioc.internal.RegistryWrapper.performRegistryStartup(RegistryWrapper.java:89)
at org.apache.tapestry5.TapestryFilter.init(TapestryFilter.java:110)
at org.eclipse.jetty.servlet.FilterHolder.initialize(FilterHolder.java:138)
at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:852)
at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:298)
at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1349)
at org.eclipse.jetty.maven.plugin.JettyWebAppContext.startWebapp(JettyWebAppContext.java:297)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1342)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:741)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:505)
at org.eclipse.jetty.maven.plugin.JettyWebAppContext.doStart(JettyWebAppContext.java:366)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
at org.eclipse.jetty.server.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:163)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
at org.eclipse.jetty.server.Server.start(Server.java:387)
at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
at org.eclipse.jetty.server.Server.doStart(Server.java:354)
at org.eclipse.jetty.maven.plugin.JettyServer.doStart(JettyServer.java:73)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.maven.plugin.AbstractJettyMojo.startJetty(AbstractJettyMojo.java:535)
at org.eclipse.jetty.maven.plugin.AbstractJettyMojo.execute(AbstractJettyMojo.java:358)
at org.eclipse.jetty.maven.plugin.JettyRunMojo.execute(JettyRunMojo.java:167)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
Caused by: java.lang.RuntimeException: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
at org.apache.tapestry5.ioc.internal.StartupDefImpl$1.run(StartupDefImpl.java:84)
at org.apache.tapestry5.ioc.internal.OperationTrackerImpl.run(OperationTrackerImpl.java:56)
... 59 more
Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:244)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:208)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:217)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:770)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:797)
at org.hibernate.jpa.HibernatePersistenceProvider.createContainerEntityManagerFactory(HibernatePersistenceProvider.java:135)
at org.apache.tapestry5.internal.jpa.EntityManagerSourceImpl.createEntityManagerFactory(EntityManagerSourceImpl.java:224)
at org.apache.tapestry5.internal.jpa.EntityManagerSourceImpl.getEntityManagerFactory(EntityManagerSourceImpl.java:200)
at org.apache.tapestry5.internal.jpa.EntityManagerSourceImpl.create(EntityManagerSourceImpl.java:293)
at $EntityManagerSource_b8af25bcbdf4.create(Unknown Source)
at org.apache.tapestry5.internal.jpa.EntityManagerManagerImpl.getOrCreateEntityManager(EntityManagerManagerImpl.java:80)
at org.apache.tapestry5.internal.jpa.EntityManagerManagerImpl.createAllEntityManagers(EntityManagerManagerImpl.java:70)
at org.apache.tapestry5.internal.jpa.EntityManagerManagerImpl.getEntityManagers(EntityManagerManagerImpl.java:61)
at $EntityManagerManager_b8af25bcbdf3.getEntityManagers(Unknown Source)
at $EntityManagerManager_b8af25bcbdf2.getEntityManagers(Unknown Source)
at org.apache.tapestry5.jpa.modules.JpaModule.startupEarly(JpaModule.java:187)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tapestry5.ioc.internal.StartupDefImpl$1.run(StartupDefImpl.java:70)
... 60 more
Caused by: org.hibernate.boot.registry.classloading.spi.ClassLoadingException: Unable to load class []
at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:229)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.loadDriverIfPossible(DriverManagerConnectionProviderImpl.java:183)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildCreator(DriverManagerConnectionProviderImpl.java:139)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:78)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:217)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:145)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:234)
... 86 more
Caused by: java.lang.ClassNotFoundException:
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:226)
... 97 more
您可能会意识到，我也在使用挂毯，但我想这无关紧要。
值得注意的是，我连接的表之前已经存在（没有连接），因此已经在persistence.xml中进行了定义。
我在代码中找不到引起异常的部分，并且消息Unable to load class []对我没有多大帮助。进入反编译类也无济于事，所以我在这里没什么主意。
由于我没有找到与此错误消息有关的类名为空的任何内容（与类似this之类的帖子相比），也许您可以为我提供帮助。
如果您需要任何源代码，我可以为您编写一些代码，类似于原始代码，但是我无法提供原始代码本身。但是由于我主要想对此异常消息进行解释，所以这应该不是问题。
编辑这有点奇怪：我将本地版本恢复到git存储库的最后一个工作状态，但错误仍然存在。我想这必须与Maven有所关联。
答案 0 :(得分：0)
好吧，这真是愚蠢。
我只是忘了构建整个项目-我一直使用IntelliJ内置的 build 函数，该函数在大多数情况下都有效-但显然并非始终如此。无论如何，如果遇到相同的问题，请尝试先构建项目。