[Struts]Cannot find bean in any scope之一解

问题描述

今天在开发中遇到一奇怪问题，有一个action，在该action里使用request.setAttribute()方法将一个List类型对象放在request中，然后forward到一个jsp文件，该文件的主要内容是使用<logic:iterate>标签将这个List对象中的条目列表显示。与它同样逻辑但位于另一模块（teacher）中的代码执行正常。但这个模块（xxgl）中的代码，本来很简单的逻辑，却总是提示：

org.apache.jasper.JasperException: Cannot find bean t in any scope

at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:254)

at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)

at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)

at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:432)

at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:356)

at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1069)

at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:455)

at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:279)

at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)

at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)

at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)

at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549)

at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589)

at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666)

at java.lang.Thread.run(Unknown Source)

将<logic:iterate>之间的代码去掉后就不会提示错误了，所以怀疑是<bean:write>中的代码有错误。相关文件ListSfzxJbxxAction.java中的execute方法如下：

public ActionForward execute(

ActionMapping mapping,

ActionForm form,

HttpServletRequest request,

HttpServletResponse response)

throws Exception {

HibernateDAO dao = HibernateDAO.getInstance(getServlet().getServletContext());

List sfzxjbxxs = dao.find("from " + SfzxJbxx.class.getName());

SfzxJbxx tmp = new SfzxJbxx();

tmp.setSfzxid("id");

tmp.setXxdm("pku");

sfzxjbxxs.add(tmp);

request.setAttribute("sfzxjbxxs", sfzxjbxxs);

return mapping.findForward("success");

}

listsfzxjbxx.jsp内容如下：

@ page contentType="text/html;charset=UTF-8" language="java" %>

@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean"%>

@ taglib uri="/WEB-INF/struts-html.tld" prefix="html"%>

<head>

<title>SfzxJbxxList</title>

</head>

<body>

<logic:iterate name="sfzxjbxxs" id="sfzxjbxx">

<tr>

<bean:write name="sfzxjbxx" property="sfzxId" filter="true"/>

</td>

<bean:write name="sfzxjbxx" property="xxdm" filter="true"/>

</td>

<td>

</td>

</tr>

</logic:iterate>

<body>

</html>

模块配置文件中相关内容如下：

<action-mappings>

<action

attribute="Form"

input="/form/sfzxjbxx.jsp"

name="sfzxJbxxForm"

path="/saveSfzxJbxx"

type="edu.pku.cc.sfzx.xxgl.action.SaveSfzxJbxxAction" />

</action>

</action-mappings>

问题解决

经过三个小时的检查，发现是listsfzxjbxx.jsp里缺少<logic:iterate>标签的声明，在前面增加上：

<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic"%>

一切OK！

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