最近在使用Ajax调用action获取数据时提示如下错误：

java.lang.NoClassDefFoundError: org/apache/commons/lang/xwork/StringUtils

经过几番苦战，尝试各种办法调试，最后发现不是写法的问题，而是struts2-json-plugin版本的问题；从目前的经验来看，我遇到的大部分问题都是jar包不全或者版本不匹配导致的。

这个是struts2-json-plugin-2.3.8的下载地址：

http://download.csdn.net/download/huangbye/7694131

详细错误如下：

exception

javax.servlet.ServletException: Filter execution threw an exception

root cause

java.lang.NoClassDefFoundError: org/apache/commons/lang/xwork/StringUtils
	org.apache.struts2.json.SerializationParams.<init>(SerializationParams.java:57)
	org.apache.struts2.json.JSONResult.writeToResponse(JSONResult.java:214)
	org.apache.struts2.json.JSONResult.execute(JSONResult.java:204)
	com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275)
	org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
	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:254)
	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:254)
	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:139)
	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:562)
	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)

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struts2-json-plugin-2.1.8.1引发的错误