学习OSGi Web开发过程中遇到的问题及解决方案汇总，以便查询。
学习过程
1. 利用felix和struts2实现osgi web（一）
引用文章：http://xingtongkun-tom-com.javaeye.com/blog/793517
问题汇总：
1. java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
严重: Dispatcher initialization failed
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at com.opensymphony.xwork2.inject.ContainerImpl$MethodInjector.inject(ContainerImpl.java:295)
at com.opensymphony.xwork2.inject.ContainerImpl$ConstructorInjector.construct(ContainerImpl.java:431)
at com.opensymphony.xwork2.inject.ContainerBuilder$5.create(ContainerBuilder.java:207)
at com.opensymphony.xwork2.inject.Scope$2$1.create(Scope.java:51)
at com.opensymphony.xwork2.inject.ContainerBuilder$3.create(ContainerBuilder.java:93)
……
Caused by: java.lang.reflect.InvocationTargetException
今天试了一下一下Struts2.2.1，按照tutorials方式部署后启动tomcat就报这个错误，后来查询网上讲要放一个javassist-3.7.ga.jar进去，解压了一个war，然后把这个包放进去，就没有这个错误了！
2. org.osgi.framework.BundleException: Fragments with exports, imports, or native code are not currently supported.
Felix 1.4是tmd半成品，更新版本
3. java.lang.IllegalArgumentException: Can't convert argument: null
at org.apache.tomcat.util.IntrospectionUtils.convert(IntrospectionUtils.java:1005)
at org.apache.tomcat.util.digester.CallMethodRule.end(CallMethodRule.java:523)
at org.apache.tomcat.util.digester.Rule.end(Rule.java:229)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1138)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:601)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1782)
……
web.xml文件中参数格式不正确
4. 在根据上文启动struts-osgi-demo-bundle-2.2.1.1.jar时出现以下错误：
严重: Exception sending context initialized event to listener instance of class org.apache.struts2.dispatcher.ng.listener.StrutsListener
Unable to load configuration. - action - bundle://2.0:1/struts.xml:9:64
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:428)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:69)
at org.apache.struts2.dispatcher.ng.listener.StrutsListener.contextInitialized(StrutsListener.java:47)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4135)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4630)
……
Caused by: Unable to load configuration. - action - bundle://2.0:1/struts.xml:9:64
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:371)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:415)
... 26 more
Caused by: Action class [helloWorldAction] not found - action - bundle://2.0:1/struts.xml:9:64
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:420)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:365)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:479)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:275)
at org.apache.struts2.osgi.BundlePackageLoader.loadPackages(BundlePackageLoader.java:58)
at org.apache.struts2.osgi.OsgiConfigurationProvider.loadConfigFromBundle(OsgiConfigurationProvider.java:135)
at org.apache.struts2.osgi.OsgiConfigurationProvider.loadPackages(OsgiConfigurationProvider.java:100)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:215)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
... 28 more
这个应该是找不到xml配置文件，据说只要在struts.xml文件中加入如下配置即可：
<constant name="struts.objectFactory" value="osgi" />
<constant name="struts.objectFactory.delegate" value="springOsgi" />
5. 严重: Exception sending context initialized event to listener instance of class org.apache.struts2.dispatcher.ng.listener.StrutsListener
Class: com.opensymphony.xwork2.spring.SpringObjectFactory
File: SpringObjectFactory.java
Method: getClassInstance
Line: 220 - com/opensymphony/xwork2/spring/SpringObjectFactory.java:220:-1
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:428)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:69)
at org.apache.struts2.dispatcher.ng.listener.StrutsListener.contextInitialized(StrutsListener.java:47)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4135)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4630)
……
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.NullPointerException
at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:220)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyResultType(XmlConfigurationProvider.java:530)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addResultTypes(XmlConfigurationProvider.java:501)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:457)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:275)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:111)
... 26 more
把struts-spring-plugin.jar从lib中去掉