java – 不知道如何迭代提供的“项目”
作者:互联网
我在我的应用程序中使用JSF 1.2.我试图遍历一个String数组,这个数组在我的支持bean中定义,如下所示:
private String[] services;
下面是faces-config文件中的托管bean条目:
<managed-bean>
<managed-bean-name>registrationBean</managed-bean-name>
<managed-bean-class>com.bean.RegistrationBean</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
我试图迭代用户选择的服务并将其显示在我的屏幕上.以下是我使用的代码:
<c:forEach items="#{registrationBean.services}" var="service">
<c:out value="${service}"></c:out>
</c:forEach>
但是我收到了错误:
Don't know how to iterate over supplied "items" in <c:forEach>
请告诉我如何解决这个问题.
编辑
如果我将String []更改为List< String>然后我得到这个例外:
java.lang.RuntimeException: wrapped Exception: java.lang.UnsupportedOperationException
com.icesoft.faces.webapp.http.servlet.MainServlet.service(MainServlet.java:156)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.icesoft.faces.webapp.xmlhttp.BlockingServlet.service(BlockingServlet.java:56)
下面是Backing Bean初始化:
private List<String> services;
public RegistrationBean() {
this.services = new ArrayList<String>();
}
faces-config.xml中:
<?xml version='1.0' encoding='UTF-8'?>
<managed-bean>
<managed-bean-name>registrationBean</managed-bean-name>
<managed-bean-class>com.bean.RegistrationBean</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
<navigation-rule>
<description>This will navigate to the Success screen.</description>
<from-view-id>/registration.jspx</from-view-id>
<navigation-case>
<from-outcome>success</from-outcome>
<to-view-id>/success.jspx</to-view-id>
</navigation-case>
</navigation-rule>
web.xml中:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<description>
ICEfaces Address Demo
</description>
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>server</param-value>
</context-param>
<context-param>
<param-name>javax.faces.application.CONFIG_FILES</param-name>
<param-value>/WEB-INF/faces-config.xml</param-value>
</context-param>
<context-param>
<param-name>com.sun.faces.validateXml</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>com.icesoft.faces.synchronousUpdate</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.jspx</param-value>
</context-param>
<listener>
<listener-class>com.icesoft.faces.util.event.servlet.ContextEventRepeater</listener-class>
</listener>
<!-- Faces Servlet -->
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup> 1 </load-on-startup>
</servlet>
<servlet>
<servlet-name>Persistent Faces Servlet</servlet-name>
<servlet-class>com.icesoft.faces.webapp.xmlhttp.PersistentFacesServlet</servlet-class>
<load-on-startup> 1 </load-on-startup>
</servlet>
<servlet>
<servlet-name>Blocking Servlet</servlet-name>
<servlet-class>com.icesoft.faces.webapp.xmlhttp.BlockingServlet</servlet-class>
<load-on-startup> 1 </load-on-startup>
</servlet>
<!-- Faces Servlet Mapping -->
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.faces</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.jspx</url-pattern>
</servlet-mapping>
<!-- Persistent Faces Servlet Mapping -->
<servlet-mapping>
<servlet-name>Persistent Faces Servlet</servlet-name>
<url-pattern>*.iface</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Persistent Faces Servlet</servlet-name>
<url-pattern>/xmlhttp/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Blocking Servlet</servlet-name>
<url-pattern>/block/*</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>30</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
解决方法:
如果您使用的是JSF 1.2,我无法解释为什么会出现此问题.很可能您的项目或环境混乱了重复或冲突的库.或者你的faces-config.xml被声明为符合JSF 1.1而不是JSF 1.2.或者也许ICEfaces以某种方式发挥了作用,但我无法分辨,因为我从未真正使用过该库.
无论如何,当你实际使用JSF 1.1时,我可以特别解释这个问题.然后,根本不支持JSP标记中的#{}和< c:forEach items>会产生这个错误.
Don’t know how to iterate over supplied “items” in <c:forEach>
然后,您应该始终在JSP标记中使用${}.但是,当${}尚未在范围中出现时,${}将不会自动创建JSF托管bean.在这种情况下,< c:forEach>将有效地获得一个空集合并且不渲染任何东西(但因此不会产生你正面临的错误!).
因此,您需要确保在< c:forEach>之前已经自动处理了JSF托管bean.进入.你可以通过使用像< h:panelGroup rendered =“#{not empty bean.list}”>的完整的JSF组件来做到这一点.包装标签,或< h:outputText value =“#{bean.text}”>在标签之前.
例如.
<h:someComponent someAttribute="#{registrationBean.something}" />
<c:forEach items="${registrationBean.services}" var="service">
<c:out value="${service}" />
</c:forEach>
一个完整的JSF 1.x替代方案是使用Tomahawk’s< t:dataList>而不是JSTL< c:forEach>.
<t:dataList value="#{registrationBean.services}" var="service">
<h:outputText value="#{service}" />
</t:dataList>
标签:java,jsp,jsf,jstl,jsf-1-2 来源: https://codeday.me/bug/20190620/1244552.html