struts2 检索属性 = 参数的通用属性类时出错

Question

我收到以下异常。任何关于为什么会发生的输入都会有所帮助

DEBUG [http-8081-1] (CommonsLogger.java:72) - Error while retrieving generic property class for property=parameters java.lang.NullPointerException at com.opensymphony.xwork2.conversion.impl.DefaultObjectTypeDeterminer.getClass(DefaultObjectTypeDeterminer.java:314) at com.opensymphony.xwork2.conversion.impl.DefaultObjectTypeDeterminer.getKeyClass(DefaultObjectTypeDeterminer.java:93) at com.opensymphony.xwork2.ognl.accessor.XWorkMapPropertyAccessor.getProperty(XWorkMapPropertyAccessor.java:93) at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:2230) at ognl.ASTProperty.getValueBody(ASTProperty.java:114) at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212) at ognl.SimpleNode.getValue(SimpleNode.java:258) at ognl.ASTChain.getValueBody(ASTChain.java:141) at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212) at ognl.SimpleNode.getValue(SimpleNode.java:258) at ognl.Ognl.getValue(Ognl.java:494) at com.opensymphony.xwork2.ognl.OgnlUtil.getValue(OgnlUtil.java:217) at com.opensymphony.xwork2.ognl.OgnlValueStack.getValue(OgnlValueStack.java:342) at com.opensymphony.xwork2.ognl.OgnlValueStack.tryFindValue(OgnlValueStack.java:331) at com.opensymphony.xwork2.ognl.OgnlValueStack.tryFindValueWhenExpressionIsNotNull(OgnlValueStack.java:307) at com.opensymphony.xwork2.ognl.OgnlValueStack.findValue(OgnlValueStack.java:293) at org.apache.struts2.components.Property.start(Property.java:162) at org.apache.struts2.views.freemarker.tags.CallbackWriter.onStart(CallbackWriter.java:73) at freemarker.core.Environment.visit(Environment.java:296) at freemarker.core.UnifiedCall.accept(UnifiedCall.java:130) at freemarker.core.Environment.visit(Environment.java:210) at freemarker.core.MixedContent.accept(MixedContent.java:92) at freemarker.core.Environment.visit(Environment.java:210) at freemarker.core.IfBlock.accept(IfBlock.java:82) at freemarker.core.Environment.visit(Environment.java:210) at freemarker.core.MixedContent.accept(MixedContent.java:92) at freemarker.core.Environment.visit(Environment.java:210) at freemarker.core.IfBlock.accept(IfBlock.java:82) at freemarker.core.Environment.visit(Environment.java:210) at freemarker.core.MixedContent.accept(MixedContent.java:92) at freemarker.core.Environment.visit(Environment.java:210) at freemarker.core.Environment.process(Environment.java:190) at freemarker.template.Template.process(Template.java:237) at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:157) at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:559) at org.apache.struts2.components.ClosingUIBean.start(ClosingUIBean.java:59) at org.apache.struts2.views.jsp.ComponentTagSupport.doStartTag(ComponentTagSupport.java:53) at org.apache.jsp.pages.THDPaymentMethod_jsp._jspx_meth_s_005fsubmit_005f1(THDPaymentMethod_jsp.java:6665) at org.apache.jsp.pages.THDPaymentMethod_jsp._jspx_meth_s_005fform_005f0(THDPaymentMethod_jsp.java:2363) at org.apache.jsp.pages.THDPaymentMethod_jsp._jspService(THDPaymentMethod_jsp.java:347) 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:377) 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(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

Answer 1

当我使用图像类型的提交标记库时，我遇到了同样的问题。 此外，我下载了struts2示例2.2.1

我添加到 struts2-showcase-2.2.1/conversion/enterPersonsInfo.jsp 表单，它会生成之前描述的错误。

您能否告诉我它是否可以通过 struts2-showcase 示例在您身边重现？

在 Jonas4.10.3 上使用 struts2.2.1 测试

Answer 2

你显然有一个 NullPointer 因为你没有设置参数属性。也许您只是忘记公开此属性，但如果您只是发布堆栈跟踪，我们可以为您提供的所有帮助都是向您朗读消息。