struts2 在<s:form>之间添加<s:textfield>或其他标签是出现可能的错误

情况一：

 

代码如下时的错误：

<s:form action="hellosport"  method="post" validate="true" namespace="/sportlogin">                <s:textfield name="user.username" label="用户名"> </s:textfield><br />                <s:password  name="user.password" label="密码"> </s:password>                  <s:radio name="userType" list="#{'1':'普通用户','2':'管理员'}" value="1"/>          </s:form>

错误如下：

2013-6-9 9:35:42 freemarker.log.JDK14LoggerFactory$JDK14Logger errorSEVERE: Template processing error: "Method public java.util.List org.apache.struts2.components.Form.getValidators(java.lang.String) threw an exception when invoked on org.apache.struts2.components.Form@3c173c17"Throwable occurred: Method public java.util.List org.apache.struts2.components.Form.getValidators(java.lang.String) threw an exception when invoked on org.apache.struts2.components.Form@3c173c17The problematic instruction:----------==> list tag.getValidators("${tagName}") as validator [on line 46, column 9 in template/xhtml/form-close-validate.ftl] in include "/${parameters.templateDir}/xhtml/form-close-validate.ftl" [on line 25, column 1 in template/xhtml/form-close.ftl]----------Java backtrace for programmers:----------freemarker.template.TemplateModelException: Method public java.util.List org.apache.struts2.components.Form.getValidators(java.lang.String) threw an exception when invoked on org.apache.struts2.components.Form@3c173c17at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:130)at freemarker.core.MethodCall._getAsTemplateModel(MethodCall.java:93)at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)at freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)at freemarker.core.Environment.visit(Environment.java:428)at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.MixedContent.accept(MixedContent.java:92)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.MixedContent.accept(MixedContent.java:92)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.Environment.include(Environment.java:1508)at freemarker.core.Include.accept(Include.java:169)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.MixedContent.accept(MixedContent.java:92)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.Environment.process(Environment.java:199)at freemarker.template.Template.process(Template.java:259)at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:157)at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:573)at org.apache.struts2.components.UIBean.end(UIBean.java:527)at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)at org.apache.jsp.userjsp.login_jsp._jspx_meth_s_005fform_005f0(login_jsp.java:159)at org.apache.jsp.userjsp.login_jsp._jspService(login_jsp.java:81)at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:88)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)at java.lang.Thread.run(Thread.java:736)Caused by: java.lang.NullPointerExceptionat com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.buildValidatorKey(AnnotationActionValidatorManager.java:237)at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.getValidators(AnnotationActionValidatorManager.java:94)at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.getValidators(AnnotationActionValidatorManager.java:90)at org.apache.struts2.components.Form.getValidators(Form.java:265)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:600)at freemarker.ext.beans.BeansWrapper.invokeMethod(BeansWrapper.java:866)at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:106)... 53 more2013-6-9 9:35:42 org.apache.catalina.core.StandardWrapperValve invokeSEVERE: Servlet.service() for servlet [jsp] in context with path [/MySportWeb] threw exception [Method public java.util.List org.apache.struts2.components.Form.getValidators(java.lang.String) threw an exception when invoked on org.apache.struts2.components.Form@3c173c17 - Class: freemarker.ext.beans.SimpleMethodModelFile: SimpleMethodModel.javaMethod: execLine: 130 - freemarker/ext/beans/SimpleMethodModel.java:130:-1] with root causeThrowable occurred: java.lang.NullPointerExceptionat com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.buildValidatorKey(AnnotationActionValidatorManager.java:237)at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.getValidators(AnnotationActionValidatorManager.java:94)at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.getValidators(AnnotationActionValidatorManager.java:90)at org.apache.struts2.components.Form.getValidators(Form.java:265)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:600)at freemarker.ext.beans.BeansWrapper.invokeMethod(BeansWrapper.java:866)at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:106)at freemarker.core.MethodCall._getAsTemplateModel(MethodCall.java:93)at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)at freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)at freemarker.core.Environment.visit(Environment.java:428)at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.MixedContent.accept(MixedContent.java:92)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.MixedContent.accept(MixedContent.java:92)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.Environment.include(Environment.java:1508)at freemarker.core.Include.accept(Include.java:169)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.MixedContent.accept(MixedContent.java:92)at freemarker.core.Environment.visit(Environment.java:221)at freemarker.core.Environment.process(Environment.java:199)at freemarker.template.Template.process(Template.java:259)at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:157)at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:573)at org.apache.struts2.components.UIBean.end(UIBean.java:527)at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)at org.apache.jsp.userjsp.login_jsp._jspx_meth_s_005fform_005f0(login_jsp.java:159)at org.apache.jsp.userjsp.login_jsp._jspService(login_jsp.java:81)at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:88)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)at java.lang.Thread.run(Thread.java:736)

解决办法：

将代码改成如下就可以了：

<s:form action="hellosport.action"  method="post" validate="true" namespace="/sportlogin">                <s:textfield name="user.username" label="用户名"> </s:textfield><br />                <s:password  name="user.password" label="密码"> </s:password>                  <s:radio name="userType" list="#{'1':'普通用户','2':'管理员'}" value="1"/>          </s:form>