Question

为struts2.it提供了三个文件，没有给出output.its给出 jasper exception.please找到错误

========================

updatedesig.jsp

=======================

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib prefix="p" uri="/struts-tags" %>
<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
</head>
<body>
    <p:form action="count"method="post">
    <p:select name="country" list="countryList"  label="Select a country" />/*creating         list in jsp*/
    </p:form>
    <h1>Hello World!</h1>
</body>
</html>

========================

struts.xml

========================

<struts>

<package name="b" extends="struts-default">
<action name="count" class="b.Countr" >/*action class is Countr.java*/

  <result name="success">updatedesig.jsp</result>
 </action>
 </package>
 </struts>

============================

Countr.java

============================

 package b;

 import java.util.ArrayList;
 import com.opensymphony.xwork2.ActionSupport;

 public class Countr extends ActionSupport/*class Countr*/
 {

 public ArrayList countrylist;
 String country;

 public  ArrayList getCountrylist()/*getting countrylist*/
 {
 return countrylist;
 }
 public void setCountrylist( ArrayList countrylist)/*setting countrylist*/
 {
 this.countrylist=countrylist;
 }
 public  String getCountry()/*getting country*/
 {
 return country;
 }
 public void setCountry( String country)/*setting country*/
 {
 this.country=country;
 }



 public String execute() 
 {
   countrylist = new ArrayList();/*creating the arraylist*/
   countrylist.add("1");
   countrylist.add("!");
   countrylist.add("1");
   return SUCCESS;

}

}

/ * Glassfish服务器日志的某些部分* /

WARNING: StandardWrapperValve[jsp]: PWC1406: Servlet.service() for servlet jsp threw exception
tag 'select', field 'list', name 'country': The requested list key 'countryList' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
    at org.apache.struts2.components.Component.fieldError(Component.java:237)
    at org.apache.struts2.components.Component.findValue(Component.java:358)
    at org.apache.struts2.components.ListUIBean.evaluateExtraParams(ListUIBean.java:80)
    at org.apache.struts2.components.Select.evaluateExtraParams(Select.java:105)
    at org.apache.struts2.components.UIBean.evaluateParams(UIBean.java:856)
    at org.apache.struts2.components.UIBean.end(UIBean.java:510)
    at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
    at org.apache.jsp.updatedesig_jsp._jspx_meth_p_select_0(updatedesig_jsp.java:138)
    at org.apache.jsp.updatedesig_jsp._jspx_meth_p_form_0(updatedesig_jsp.java:107)
    at org.apache.jsp.updatedesig_jsp._jspService(updatedesig_jsp.java:68)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:403)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:492)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:378)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:88)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:722)

Answer 1

总是更好地提供系统抛出的错误/异常，其他人很难告诉任何东西。而且没有人有那么多时间在那里编写程序并看到错误。

我可能出错的第一个镜头是

<p:select name="country" list="countryList"  label="Select a country" />

这意味着它会尝试在您的操作类中找到受尊重的getter方法getCountryList()，但您的操作类具有以下方法

public  ArrayList getCountrylist()/*getting countrylist*/
 {
 return countrylist;
 }

将选择更改为

  <p:select name="country" list="countrylist"  label="Select a country" />

或在您的动作类中进行必要的更正。

总是建议编程接口而不是实现，这将为您提供更大的灵活性。

您可以创建List并使用ArrayList对其进行初始化。以下是适用于我的内容

行动类

List<String> countryList;

public List<String> getCountryList() {
        return countryList;
    }

public void setCountryList(List<String> countryList) {
        this.countryList = countryList;
}

countryList=new ArrayList<String>();
        countryList.add("1");
        countryList.add("!");
        countryList.add("1");

JSP类

<s:select name="country" list="countryList"  label="Select a country" />

输出

enter image description here

在Struts2下拉列表程序中找到错误？

1 个答案:

行动类

JSP类

输出