Eclipse + GWT + spring + maven: classnotfoundexception

Question

I have a weird problem with my setup that I don't understand. I'm working on a maven GWT project that runs fine in a shell (i.e. mvn gwt:run is working as expected).

However, when I try to run it in Eclipse (with m2e and gwt plugin installed), I get a classnotfoundexception. The class is an entity class and the exception occurs when the entity manager is built. I checked that the class is declared in the persistence.xml and I cannot find any exclusion in the pom.xml or the eclipse build path.

On top of this, it works fine for someone else working on the exact same project.

My guess is that I have a configuration error in Eclipse but I didn't tweek anything.

Any ideas?

Eclipse 4.2
GWT 2.4
Maven 3.0.3
Spring 3.0.5

[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

1) Try executing mvn clean install and then launching the hosted mode. If it works this means some classes/files need to be copied into target for your project to work.

2) If you trying to use Google GWT Webapp Launch, then check your launch folders for arguments. You should try and align it to maven's set up of target, artifact with/without version id etc

3) Check your project names to see if you have imported the maven project with versionid suffix to your project. This might be causing some classpath issues.

Answer 2

It could be the classloading of GWT-Eclipse. By default when running a GWT application from Eclipse all jars in the lib folder are added to the running applications classpath. In addition when Eclipse-GWT comes across any classes that are not on this classpath it searches the system classpath. If it finds the class the corresponding jar is also added to the running applications classpath. This will be logged in the console.

Generally this is okay but it does cause issues when you search the classpath. Classes won't be found unless the jar has been added to the running classpath by Eclipse. You can hack things but its not ideal (see the answer to this question).

I am guessing that with Maven all the Maven dependency jars are being added to the system classpath. When combined with Spring and JPA then there is a lot of classpath searching going on.

That doesn't explain why it works on another persons mechine - unless they have additional jars in their web app lib folder.

As to how to fix it "properly" I am not sure. I am in the same position myself - I have one application that works and one that is configured in a very similar way that doesn't. It's also the reason I found this question!