Eclipse GWTSpring专家

Question

我的设置有一个奇怪的问题，我不明白。我正在从事一个maven GWT项目，该项目在shell中运行良好（即mvn GWT:run按预期工作）。

然而，当我尝试在Eclipse中运行它（安装了m2e和gwt插件）时，我得到了一个classnotfoundexception。该类是一个实体类，在生成实体管理器时会发生异常。我检查了该类是否在持久性中声明。xml和我在pom中找不到任何排除项。xml或eclipse构建路径。

最重要的是，它适用于从事完全相同项目的其他人。

我的猜测是，我在Eclipse中有一个配置错误，但我没有发现任何错误。

有什么想法吗？

Eclipse4.2
GWT2.4
Maven 3.0。3
Spring3.0。5.

[WARN] Failed startup of context com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload@57790a{/,C:\Users\gere\Documents\netlight-workspace\NET2\target}
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManager' defined in ServletContext resource [/WEB-INF/database.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: netlight_db] class or package not found
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1420)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:563)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:543)
at org.mortbay.jetty.servlet.Context.startContext(Context.java:136)
at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1220)
at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:513)
at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:468)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.jetty.handler.RequestLogHandler.doStart(RequestLogHandler.java:115)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.jetty.Server.doStart(Server.java:222)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:672)
at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
at com.google.gwt.dev.DevMode.main(DevMode.java:311)
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: netlight_db] class or package not found
at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1386)
at org.hibernate.ejb.Ejb3Configuration.addClassesToSessionFactory(Ejb3Configuration.java:1159)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:1004)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:689)
at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:73)
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
... 30 more
Caused by: java.lang.ClassNotFoundException: se.netlight.projectplusgui.server.dbo.BusinessArea
at java.lang.ClassLoader.findClass(ClassLoader.java:358)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:352)
at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:337)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:170)
at org.hibernate.ejb.Ejb3Configuration.classForName(Ejb3Configuration.java:1302)
at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1374)
... 38 more
[WARN] Nested in org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManager' defined in ServletContext resource [/WEB-INF/database.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: netlight_db] class or package not found:
java.lang.ClassNotFoundException: se.netlight.projectplusgui.server.dbo.BusinessArea
at java.lang.ClassLoader.findClass(ClassLoader.java:358)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:352)
at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:337)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:170)
at org.hibernate.ejb.Ejb3Configuration.classForName(Ejb3Configuration.java:1302)
at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1374)
at org.hibernate.ejb.Ejb3Configuration.addClassesToSessionFactory(Ejb3Configuration.java:1159)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:1004)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:689)
at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:73)
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:563)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:543)
at org.mortbay.jetty.servlet.Context.startContext(Context.java:136)
at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1220)
at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:513)
at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:468)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.jetty.handler.RequestLogHandler.doStart(RequestLogHandler.java:115)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.jetty.Server.doStart(Server.java:222)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:672)
at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
at com.google.gwt.dev.DevMode.main(DevMode.java:311)

Answer 1

这可能是GWT Eclipse的类加载。默认情况下，从Eclipse运行GWT应用程序时，lib文件夹中的所有JAR都会添加到正在运行的应用程序类路径中。此外，当EclipseGWT遇到任何不在此类路径上的类时，它会搜索系统类路径。如果找到该类，则相应的jar也会添加到正在运行的应用程序类路径中。这将记录在控制台中。

一般来说，这是可以的，但是当您搜索类路径时，它确实会导致问题。除非通过Eclipse将jar添加到正在运行的类路径中，否则不会找到类。你可以破解东西，但这并不理想（见这个问题的答案）。

我猜在Maven中，所有Maven依赖JAR都被添加到系统类路径中。当与Spring和JPA结合使用时，就会有大量的类路径搜索。

这并不能解释为什么它能在其他人的机器上工作——除非他们的web应用程序库文件夹中有额外的JAR。

至于如何“正确地”修复它，我不确定。我自己也处于同样的位置——我有一个可以工作的应用程序，还有一个配置方式非常类似，但没有。这也是我发现这个问题的原因！

Answer 2

1） 尝试执行mvn clean install，然后启动托管模式。如果可行，这意味着需要将某些类/文件复制到目标中，项目才能正常工作。

2） 如果您试图使用Google GWT Webapp启动，请检查启动文件夹中的参数。您应该尝试将它与maven的目标设置、带有/不带有版本id的工件等对齐

3）检查您的项目名称，看看您是否已经将带有versionid后缀的maven项目导入到您的项目中。这可能会导致一些类路径问题。