java后台传入前台json问题

org.apache.struts2.json.JSONException: java.lang.reflect.InvocationTargetException
	org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:238)
	org.apache.struts2.json.JSONWriter.processCustom(JSONWriter.java:171)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:161)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.array(JSONWriter.java:455)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:151)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.map(JSONWriter.java:410)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:147)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.write(JSONWriter.java:95)
	org.apache.struts2.json.JSONUtil.serialize(JSONUtil.java:116)
	org.apache.struts2.json.JSONResult.createJSONString(JSONResult.java:196)
	org.apache.struts2.json.JSONResult.execute(JSONResult.java:170)
	com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275)
	org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
	org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
	org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
	org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

root cause

java.lang.reflect.InvocationTargetException
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:218)
	org.apache.struts2.json.JSONWriter.processCustom(JSONWriter.java:171)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:161)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.array(JSONWriter.java:455)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:151)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.map(JSONWriter.java:410)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:147)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.write(JSONWriter.java:95)
	org.apache.struts2.json.JSONUtil.serialize(JSONUtil.java:116)
	org.apache.struts2.json.JSONResult.createJSONString(JSONResult.java:196)
	org.apache.struts2.json.JSONResult.execute(JSONResult.java:170)
	com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275)
	org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
	org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
	org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
	org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

root cause

net.sf.json.JSONException: Object is null
	net.sf.json.JSONNull.isEmpty(JSONNull.java:69)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:218)
	org.apache.struts2.json.JSONWriter.processCustom(JSONWriter.java:171)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:161)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.array(JSONWriter.java:455)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:151)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.map(JSONWriter.java:410)
	org.apache.struts2.json.JSONWriter.process(JSONWriter.java:147)
	org.apache.struts2.json.JSONWriter.value(JSONWriter.java:127)
	org.apache.struts2.json.JSONWriter.write(JSONWriter.java:95)
	org.apache.struts2.json.JSONUtil.serialize(JSONUtil.java:116)
	org.apache.struts2.json.JSONResult.createJSONString(JSONResult.java:196)
	org.apache.struts2.json.JSONResult.execute(JSONResult.java:170)
	com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275)
	org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
	org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
	org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
	org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

 写后台转换为json形式传入前台报错，经查百度可能造成的原因：方法名含有get字符、注入的service生成了set、get方法；导入commons-io-xx.jar和commons-fileupload.jar包有误或版本不符。经排查均不存在以上问题。根本问题为

net.sf.json.JSONException: Object is null

传入对象的属性值为null时无法使用jsonObject.accumulate(key,value);