这篇博客记录了一位初级开发者遇到的OSGI环境中Spring BeanInstantiationException问题。问题出现在试图实例化TestAction时，由于一个全局变量IDataObj设置错误导致NullPointerException。经过排查，发现错误源于在Action中错误地将IDataObj设为全局变量，解决方案是将其改为局部变量并在每个方法内使用。博主建议从简单系统开始并严格控制变量数量，以减少错误排查难度。
目前职级：初级
问题水平：初级
问题现状：[ims] 16-06-30 23:03:35:0181 ERROR CommonsLogger.error(38) | Exception occurred during processing request: Unable to instantiate Action,
com.troy.ods.system.action.TestAction, defined for 'test' in namespace '/system'Error creating bean with name 'com.troy.ods.system.action.TestAction': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.system.action.TestAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
Unable to instantiate Action, com.troy.ods.system.action.TestAction, defined for 'test' in namespace '/system'Error creating bean with name 'com.troy.ods.system.action.TestAction': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.system.action.TestAction]: Constructor threw exception; nested exception is java.lang.NullPointerExceptionat com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:316)
at com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:397)
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:194)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:37)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:552)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at com.troy.framework.tools.struts.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:77)
at com.troy.framework.core.interceptor.StrutsPrepareAndExecuteFilterEx.doFilter(StrutsPrepareAndExecuteFilterEx.java:41)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.troy.ods.system.action.TestAction': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.system.action.TestAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:278)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1114)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowire(AbstractAutowireCapableBeanFactory.java:350)
at com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:179)
at com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:154)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:171)
at com.opensymphony.xwork2.factory.DefaultActionFactory.buildAction(DefaultActionFactory.java:22)
at com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:297)
... 27 more
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.system.action.TestAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:164)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:125)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:270)
... 35 more
Caused by: java.lang.NullPointerException
at com.troy.framework.core.util.ParamUtil.getAllParamMap(ParamUtil.java:75)
at com.troy.framework.core.action.BaseAction.getRequestParamsMap(BaseAction.java:253)
at com.troy.framework.core.action.BaseAction.getDataObject(BaseAction.java:354)
at com.troy.ods.system.action.TestAction.<init>(TestAction.java:18)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148)
... 37 more
[ims] 16-06-30 23:03:35:0221 INFO StrutsPrepareAndExecuteFilterEx.doFilter(44) | 过滤链共花时间:103ms
[ims] 16-06-30 23:03:40:0631 ERROR CommonsLogger.error(38) | Exception occurred during processing request: Unable to instantiate Action, com.troy.ods.crud.action.CrudAction, defined for 'crud' in namespace '/crud'Error creating bean with name 'com.troy.ods.crud.action.CrudAction': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.crud.action.CrudAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
Unable to instantiate Action, com.troy.ods.crud.action.CrudAction, defined for 'crud' in namespace '/crud'Error creating bean with name 'com.troy.ods.crud.action.CrudAction': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.crud.action.CrudAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:316)
at com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:397)
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:194)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:37)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:552)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at com.troy.framework.tools.struts.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:77)
at com.troy.framework.core.interceptor.StrutsPrepareAndExecuteFilterEx.doFilter(StrutsPrepareAndExecuteFilterEx.java:41)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.troy.ods.crud.action.CrudAction': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.crud.action.CrudAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:278)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1114)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowire(AbstractAutowireCapableBeanFactory.java:350)
at com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:179)
at com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:154)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:171)
at com.opensymphony.xwork2.factory.DefaultActionFactory.buildAction(DefaultActionFactory.java:22)
at com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:297)
... 27 more
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.troy.ods.crud.action.CrudAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:164)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:125)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:270)
... 35 more
Caused by: java.lang.NullPointerException
at com.troy.framework.core.util.ParamUtil.getAllParamMap(ParamUtil.java:75)
at com.troy.framework.core.action.BaseAction.getRequestParamsMap(BaseAction.java:253)
at com.troy.framework.core.action.BaseAction.getDataObject(BaseAction.java:354)
at com.troy.ods.crud.action.CrudAction.<init>(CrudAction.java:25)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148)
预判原因：bean实例化问题,主页hello world可以访问。预判spring异常造成
实际原因：action中设置了错误的Idataobj为全局变量，导致其获取参数为空。进而导致action无法完成实例化
解决方案：将action中的idataobj写在每个方法的里面，然后进行调试成功。
心得：从最简系统做起，严格控制变量数量减少错误可能数量。方便查找
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