struts2 <s:debug />问题

Question

我现在做的这个项目中 jsp页面一加<s:debug />就出错 但是不加页面都是正常
异常：
The problematic instruction:
----------
==> ${stackObject.value.get(propertyName).toString()?html} [on line 58, column 120 in template/simple/debug.ftl]
----------Java backtrace for programmers:
----------
freeer.core.InvalidReferenceException: Expression stackObject.value.get(propertyName).toString() is undefined on line 58, column 122 in template/simple/debug.ftl.
at freeer.core.TemplateObject.assertNonNull(TemplateObject.java:124)
at freeer.core.Expression.getStringValue(Expression.java:118)
at freeer.core.Expression.getStringValue(Expression.java:93)
at freeer.core.StringBuiltins$StringBuiltIn._getAsTemplateModel(StringBuiltins.java:71)
at freeer.core.Expression.getAsTemplateModel(Expression.java:89)
at freeer.core.Expression.getStringValue(Expression.java:93)
at freeer.core.DollarVariable.accept(DollarVariable.java:76)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.IfBlock.accept(IfBlock.java:82)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.MixedContent.accept(MixedContent.java:92)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
at freeer.core.Environment.visit(Environment.java:417)
at freeer.core.IteratorBlock.accept(IteratorBlock.java:102)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.MixedContent.accept(MixedContent.java:92)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
at freeer.core.Environment.visit(Environment.java:417)
at freeer.core.IteratorBlock.accept(IteratorBlock.java:102)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.MixedContent.accept(MixedContent.java:92)
at freeer.core.Environment.visit(Environment.java:210)
at freeer.core.Environment.process(Environment.java:190)
at freeer.template.Template.process(Template.java:237)
at org.apache.struts2.components.template.FreeerTemplateEngine.renderTemplate(FreeerTemplateEngine.java:157)

Answer 1

at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:559)
at org.apache.struts2.components.UIBean.end(UIBean.java:513)
at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
at org.apache.jsp.page.sys.roleDefList_jsp._jspx_meth_s_005fdebug_005f0(roleDefList_jsp.java:978)
at org.apache.jsp.page.sys.roleDefList_jsp._jspService(roleDefList_jsp.java:191)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:386)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter