logic:iterate 抛出 javax.servlet.jsp.JspException: 无法为此集合创建迭代器

Question

当我执行我的应用程序时，出现错误。

问题不会来自错误的 taglib 版本？

错误：

Caused by: javax.servlet.ServletException: javax.servlet.jsp.JspException: ServletException in 'menu.jsp': javax.servlet.jsp.JspException: Cannot create iterator for this collection

我的菜单已填充到我的 java 应用程序中：

我的JSP:

<%@ taglib uri="http://struts.apache.org/tags-tiles" prefix="tiles"%>
<%@ taglib uri="http://struts.apache.org/tags-html-el" prefix="html"%>
<%@ taglib uri="http://struts.apache.org/tags-bean-el" prefix="bean"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://struts.apache.org/tags-logic-el" prefix="logic"%>
<%@ taglib tagdir="/WEB-INF/tags/" prefix="customTag"%>

<customTag:OverlayEntry id="overlaymenu" function="overlaymenu" />

<script type="text/javascript"
    src="<html:rewrite page="/javascript/jquery.easing.js"/>"></script>
<script type="text/javascript"
    src="<html:rewrite page="/javascript/jquery.accordion.js"/>"></script>
<link href="<html:rewrite page="/css/menu.css"/>" rel="stylesheet"
    type="text/css" />

<logic:present name="UserSession" property="menu">
        <ul id="navigation">
            <logic:iterate id="t" collection="${UserSession.menu.menuEntries}"
                indexId="idx">
                <customTag:MenuEntry
                    entry="<%=(com.sodifrance.apex.presentation.generic.session.MenuEntry) t%>" />
            </logic:iterate>
        </ul>
</logic:present>
<script type="text/javascript">
    jQuery('.current').parent().parent().prev('A').addClass('selected');
    jQuery('#navigation>li>A[href]').addClass('head2');

    jQuery('#navigation').Accordion({
        header : '.head',
        navigation : false,
        event : 'click',
        autoheight : false,
        animated : false,
        active : '.selected',
        selectedClass : 'selected',
        alwaysOpen : true
    });

    jQuery('#navigation>li>A.current').addClass('currentHead').removeClass(
            'current');
</script>

我的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    version="3.1">

    <display-name>APP</display-name>
    <description>Application</description>
    <filter>
        <filter-name>applicationFilter</filter-name>
        <filter-class>com.presentation.generic.security.ApplicationFilter</filter-class>
        <init-param>
            <param-name>exclusions</param-name>
            <param-value>/generic/authentification/Login.do,
                /generic/authentification/login_action.do,
                /generic/authentification/Disconnect.do,
                *.js,
                *.css,
                *.jpg,
                *.gif,
                *.png,
                *.ico
            </param-value>
        </init-param>
        <init-param>
            <param-name>loginUrl</param-name>
            <param-value>/generic/authentification/Login.do</param-value>
        </init-param>
    </filter>
    <filter>
        <filter-name>EncodingFilter</filter-name>
        <filter-class>com.presentation.generic.security.EncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>ISO-8859-15</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>applicationFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <filter-mapping>
        <filter-name>EncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
    <listener>
        <listener-class>com.presentation.generic.back.BirtEngineListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>action</servlet-name>
        <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
        <init-param>
            <param-name>config</param-name>
            <param-value>/WEB-INF/struts-config.xml</param-value>
        </init-param>
        <init-param>
            <param-name>debug</param-name>
            <param-value>2</param-value>
        </init-param>
        <init-param>
            <param-name>detail</param-name>
            <param-value>2</param-value>
        </init-param>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet>
        <servlet-name>initDB</servlet-name>
        <servlet-class>com.metier.init.DbInitializerServlet</servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>true</param-value>
        </init-param>
    </servlet>
    <servlet>
        <servlet-name>birtEngineServlet</servlet-name>
        <servlet-class>com.report.generic.BirtServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>action</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
<!--    <servlet-mapping> -->
<!--        <servlet-name>jsp</servlet-name> -->
<!--        <url-pattern>/javascript/generic/messages.js</url-pattern> -->
<!--    </servlet-mapping> -->
<!--    <servlet-mapping> -->
<!--        <servlet-name>jsp</servlet-name> -->
<!--        <url-pattern>*.css</url-pattern> -->
<!--    </servlet-mapping> -->
    <servlet-mapping>
        <servlet-name>initDB</servlet-name>
        <url-pattern>/initDB</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

动作Class:

public ActionForward logInApplication_loginAction(ActionMapping映射，ActionForm表单，HttpServletRequest请求，HttpServletResponse响应) throws Exception { 动作转发 actionForward = null; 如果（形式！=空）{ 登录操作返回代码； LoginForm currentForm = (LoginForm) 表单； // 在当前页面退出时执行代码 currentForm.onExit();

    UserSession session = null;
    AccueilForm accueilForm = new AccueilForm();

    if (validateLogin(currentForm, request)) {
        session = new UserSession();
        SessionHelper.getDefault().registerSession(session);

        initializeUserSession(currentForm, session);

        returnCode = LoginAction.LOGIN_SUCCESS;
    } else {
        ActionErrors e = new ActionErrors();
        e.add("property", new ActionMessage("authentification.Login.action.login.failed", Math.floor(Math.random() * 4)));
        addErrors(request, e);
        returnCode = LoginAction.LOGIN_FAIL;
    }

    switch (returnCode) {
        case LOGIN_FAIL:
            request.setAttribute(LoginForm.BEAN_NAME,currentForm);
            // execute code on entry of next page
            currentForm.onEntry();
            actionForward = mapping.findForward("LOGINACTION_LOGIN_FAIL");
            break;

        case LOGIN_SUCCESS:
            session.setLogin(currentForm.getLogin());
            request.getSession().setAttribute("UserSession", session);
            accueilForm.onEntry();
            request.setAttribute(AccueilForm.BEAN_NAME, accueilForm);
            actionForward = mapping.findForward("LOGINACTION_LOGIN_SUCCESS");
            break;

        default:
            break;
    }
}
return actionForward;

}

我的配置：

Tomcat 8
Struts 1.3.10
Jdk 1.8

Answer 1

你在struts标签中使用EL的问题，那不是你所期望的。

<logic:notEmpty name="UserSession" property="menu">
    <bean:define id="menuInfo" name="UserSession" property="menu"/>
    <ul id="navigation">
        <logic:iterate id="t" name="menuInfo" property="menuEntries" type="com.example.MenuEntry">
           ...

logic:iterate 抛出 javax.servlet.jsp.JspException: 无法为此集合创建迭代器

logic:iterate throws javax.servlet.jsp.JspException: Cannot create iterator for this collection

jsp

loops

struts

el