SpringMVC对象中子对象的自动封装异常处理

org.springframework.beans.NullValueInNestedPathException: Invalid property 'parent' of bean class [com.onlineexam.exam.core.entity.main.Permissions]: Could not instantiate property type [com.onlineexam.exam.core.entity.base.PermissionsBase] to auto-grow nested property path: java.lang.InstantiationException
at org.springframework.beans.BeanWrapperImpl.newValue(BeanWrapperImpl.java:633)
at org.springframework.beans.BeanWrapperImpl.createDefaultPropertyValue(BeanWrapperImpl.java:604)
at org.springframework.beans.BeanWrapperImpl.setDefaultValue(BeanWrapperImpl.java:593)
at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:558)
at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:532)
at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:890)
at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:76)
at org.springframework.validation.DataBinder.applyPropertyValues(DataBinder.java:673)
at org.springframework.validation.DataBinder.doBind(DataBinder.java:569)
at org.springframework.web.bind.WebDataBinder.doBind(WebDataBinder.java:191)
at org.springframework.web.bind.ServletRequestDataBinder.bind(ServletRequestDataBinder.java:110)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter$ServletHandlerMethodInvoker.doBind(AnnotationMethodHandlerAdapter.java:736)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:805)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:359)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1221)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.mortbay.jetty.servlet.ServletHandler$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.content(HttpConnection.java:945)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
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)

这种情况一般情况是get取得的对象为抽象类。无法进行实例化。因此需要检查对象中的子对象是否为抽象类。