JavaEE5实战笔记01EJB环境搭建及异常解决
1. 说明
此实战笔记是为了之前的学习笔记做一个实践，因为任何零散的知识点只有整合起来才更能发现问题、解决问题、从问题中提高。这次项目实战是打算做一个微型的在线网络银行，系统软件开发框架使用JSF（RI+tomahawk12-1.1.10.jar组件）+JBoss5+EJB3.0规范+JPA（JBoss内部的Hibernate实现）+Oracle10g实现。还是那句老话，有什么心得先写出来，事后恐怕就没那么多感受了。有什么错误之后再更正呗。
2. 环境搭建
采用MyEclipse8.6进行软件开发，首先建立JavaEE Web项目，之后陆续加入JPA以及JSF规范支持。JPA选择Hibernate实现即可、JSF使用默认配置。建立完成后项目特性应该有如下几个
添加完特性之后会有很多重复的jar包在项目中引用，将其从项目的build path中删除掉即可，之后再引入本项目用到的其他jar包。如下
log4j：这个不用解释了吧，在EJB开发中最麻烦的就是部署和调试，很头疼，有一个好的日志输出给程序的调试和排错解决了不少问题。
ojdbc：Oracle的JDBC驱动
jsf-facelets：JSF的一个页面框架
jsf-el-ri：JSF相关包
jsf-oro：JSF相关包
jsf-portlet：JSF关于portlet框架的相关包
tomahawk：JSF的开源组件
因为这个系统底层采用的是Hibernate作为JPA标准的框架，其实JBoss自己本身已经包含了Hibernate的相关核心包，只是笔者在持久层加入了Hibernate的特殊性配置，所以这里不得不引入Hibernate的Annotations特性包。
至于JavaEE的标准嘛~采用的是JavaEE5的标准。
目前先加入这么多jar包，之后可能随着需求的变化不断地往里面加入相关jar文件。
3. 代码包结构
笔者的实践项目叫做WebBank。项目包结构如下
ejb ejb.dto ejb.eao ejb.eao.base ejb.eao.impl ejb.service ejb.service.base ejb.service.impl util web web.action web.managedBean /WebBank/src/META-INF /WebBank/src/log4j.properties /WebBank/resource/WebBank/srcTest
如图
说明：
src、srcTest、resource都是build path包，src是项目源代码包，srcTest是单元测试源码包、resource是资源配置文件、国际化文件配置包。
src下面的ejb包是放实体Bean、会话bean、消息驱动bean的包，不仅如此，EJB组件通常都对外面提供一种faces的调用模式，因此还需要service层进行包装。util包专门放着一些辅助类，web包实际上就是放着JSF web层的控制器。因为JSF的托管bean可以服用ejb的实体bean，也就是dto中的实体类。那么其实这里manageBean并没什么用。不过先放着，给特殊的托管Bean预留。
4. 系统运行流程分析
我们来分析一下一般JavaEE软件的运行流程，流程图如下
用户从浏览器访问系统，JSF引擎开始工作，经过JSF组件的生命周期接收来自客户端的请求，将组件属性值注入到JSF控制器中，JSF控制器的托管Bean经过setter后已经被注入了相关request的值，之后调用业务Bean处理业务逻辑，业务bean是EJB容器为其注入的组件，不必set和get，直接使用即可。业务处理Bean实际就是service层，service包装了EJB容器本地的会话EAOBean，本地EAOBean也是EJB容器注入到service层的。通过EAOBean操作实体Bean完成业务逻辑。在JSF控制器层返回的结果映射，将视图恢复后、组件渲染也完毕后，呈献给客户端。
5. 遇到的异常问题以及解决方式
有句话说得好，事与愿违。虽然之前做了那么多铺垫，但是EJB就是EJB，和轻量级框架系统就是不一样。没办法，谁让咱用到了这种分布式集群解决方案呢。可能用一般的SSH框架很简单就将系统搭建完成，但是遇到EJB容器很多人还是遇到了问题，下面我们来看看仅仅是一个简单程序所经历的各种异常吧。
1）：错误如下
Caused by: org.jboss.xb.binding.JBossXBRuntimeException: {http://java.sun.com/xml/ns/javaee}param-name not found as a child of {http://java.sun.com/xml/ns/javaee}description in unordered_sequence: {http://java.sun.com/xml/ns/javaee}key?
at org.jboss.xb.binding.sunday.unmarshalling.SundayContentHandler.startElement(SundayContentHandler.java:383)
at org.jboss.xb.binding.parser.sax.SaxJBossXBParser$DelegatingContentHandler.startElement(SaxJBossXBParser.java:401)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown Source)
at org.apache.xerces.impl.xs.XMLSchemaValidator.startElement(Unknown Source)
at org.apache.xerces.xinclude.XIncludeHandler.startElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
at org.jboss.xb.binding.parser.sax.SaxJBossXBParser.parse(SaxJBossXBParser.java:199)
... 41 more
在部署web工程的时候在纯tomcat下没问题，一到了JBoss下就会出现这个异常。
解决办法
web.xml中的<context-param>不能加<description> </description>标签，可能是因为JBoss5的tomcat版本比较老了，因此不支持web工程加以上标签
2）：异常
org.hibernate.AnnotationException: Unknown Id.generator: system-uuid at org.hibernate.cfg.BinderHelper.makeIdGenerator(BinderHelper.java:428) at org.hibernate.cfg.AnnotationBinder.bindId(AnnotationBinder.java:1901) at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1279) at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:754) at org.hibernate.cfg.AnnotationConfiguration.processArtifactsOfType(AnnotationConfiguration.java:546) at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:291)
这是因为笔者在实体bean中的主键生成策略是UUID，而且使用了Hibernate的特殊标记，所以此时应该引入相关包
解决方法：
hibernate-annotations.jar hibernate-commons-annotations.jar hibernate-entitymanager.jar hibernate-validator.jar
3）：异常
java.lang.ClassCastException: org.apache.xerces.jaxp.SAXParserFactoryImpl cannot be cast to javax.xml.parsers.SAXParserFactory at javax.xml.parsers.SAXParserFactory.newInstance(Unknown Source) at com.sun.facelets.compiler.SAXCompiler.createSAXParser(SAXCompiler.java:271) at com.sun.facelets.compiler.SAXCompiler.doCompile(SAXCompiler.java:231) at com.sun.facelets.compiler.Compiler.compile(Compiler.java:105) at com.sun.facelets.impl.DefaultFaceletFactory.createFacelet(DefaultFaceletFactory.java:218) at com.sun.facelets.impl.DefaultFaceletFactory.getFacelet(DefaultFaceletFactory.java:149) at com.sun.facelets.impl.DefaultFaceletFactory.getFacelet(DefaultFaceletFactory.java:100) at com.sun.facelets.FaceletViewHandler.buildView(FaceletViewHandler.java:519) at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:569) at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110) at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100) at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:598) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:662)
解决办法
| 如果项目中有xml-apis.jar，将xml-apis.jar包去掉 |
4）：异常
下面可能是很多人都会遇到的异常，异常信息虽然比较多，但是我还是想把完整的异常信息贴出来
java.lang.ClassCastException: org.hibernate.ejb.HibernatePersistence cannot be cast to javax.persistence.spi.PersistenceProvider at org.jboss.jpa.deployment.PersistenceUnitDeployment.start(PersistenceUnitDeployment.java:300) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.jboss.reflect.plugins.introspection.ReflectionUtils.invoke(ReflectionUtils.java:59) at org.jboss.reflect.plugins.introspection.ReflectMethodInfoImpl.invoke(ReflectMethodInfoImpl.java:150) at org.jboss.joinpoint.plugins.BasicMethodJoinPoint.dispatch(BasicMethodJoinPoint.java:66) at org.jboss.kernel.plugins.dependency.KernelControllerContextAction$JoinpointDispatchWrapper.execute(KernelControllerContextAction.java:241) at org.jboss.kernel.plugins.dependency.ExecutionWrapper.execute(ExecutionWrapper.java:47) at org.jboss.kernel.plugins.dependency.KernelControllerContextAction.dispatchExecutionWrapper(KernelControllerContextAction.java:109) at org.jboss.kernel.plugins.dependency.KernelControllerContextAction.dispatchJoinPoint(KernelControllerContextAction.java:70) at org.jboss.kernel.plugins.dependency.LifecycleAction.installActionInternal(LifecycleAction.java:221) at org.jboss.kernel.plugins.dependency.InstallsAwareAction.installAction(InstallsAwareAction.java:54) at org.jboss.kernel.plugins.dependency.InstallsAwareAction.installAction(InstallsAwareAction.java:42) at org.jboss.dependency.plugins.action.SimpleControllerContextAction.simpleInstallAction(SimpleControllerContextAction.java:62) at org.jboss.dependency.plugins.action.AccessControllerContextAction.install(AccessControllerContextAction.java:71) at org.jboss.dependency.plugins.AbstractControllerContextActions.install(AbstractControllerContextActions.java:51) at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348) at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631) at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934) at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082) at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984) at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:774) at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:540) at org.jboss.deployers.vfs.deployer.kernel.BeanMetaDataDeployer.deploy(BeanMetaDataDeployer.java:121) at org.jboss.deployers.vfs.deployer.kernel.BeanMetaDataDeployer.deploy(BeanMetaDataDeployer.java:51) at org.jboss.deployers.spi.deployer.helpers.AbstractSimpleRealDeployer.internalDeploy(AbstractSimpleRealDeployer.java:62) at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50) at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:171) at org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(DeployersImpl.java:1439) at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1157) at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1178) at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:1098) at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348) at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631) at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934) at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082) at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984) at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822) at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553) at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:781) at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:702) at org.jboss.system.server.profileservice.repository.MainDeployerAdapter.process(MainDeployerAdapter.java:117) at org.jboss.system.server.profileservice.repository.ProfileDeployAction.install(ProfileDeployAction.java:70) at org.jboss.system.server.profileservice.repository.AbstractProfileAction.install(AbstractProfileAction.java:53) at org.jboss.system.server.profileservice.repository.AbstractProfileService.install(AbstractProfileService.java:361) at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348) at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631) at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934) at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082) at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984) at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822) at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553) at org.jboss.system.server.profileservice.repository.AbstractProfileService.activateProfile(AbstractProfileService.java:306) at org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:271) at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:461) at org.jboss.Main.boot(Main.java:221) at org.jboss.Main$1.run(Main.java:556) at java.lang.Thread.run(Thread.java:662)
这是因为笔者想偷懒，因为EJB项目打包、部署、重启JBoss十分费时间，所以就想将整个项目作为一个完整的工程发布到JBoss中，结果就造成了以上的异常结果。所以要将EJB组件、web组件分别打包，具体打包过程，请参考博客：
http://suhuanzheng7784877.iteye.com/blog/919899
下面就是笔者的ear文件内容：
META-INF下的application.xml内容如下
<?xml version="1.0" encoding="UTF-8"?> <application xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="5" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/application_5.xsd"> <display-name>WebBankApp</display-name> <module id="myeclipse.1303695851606"> <web> <web-uri>WebBank.war</web-uri> <context-root>/WebBank</context-root> </web> </module> <module id="myeclipse.1303695851607"> <ejb>WebBankEJB.jar</ejb> </module> </application>