我在项目中使用的是primefaces。当我在.xhtml页面中使用该组件时，我收到以下错误消息：
“标记库支持命名空间：http://primefaces.org/ui，但没有为名称定义标记：panelMenu”
我使用的是primefaces 3.3.1 jar。
代码段：
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui">
<h:head>
<title>Welcome to OTV_JSF_Spring_Hibernate_Project</title>
<style type="text/css">
h1{
font-family:"Times New Roman";
font-size:7px;
}
pre{
font-family:"Times New Roman";
font-size:25px;
font-style:bold;
align:center;
}
</style>
</h:head>
<h:body>
<h:form>
<p:layout style="min-width:300px;min-height:700px;" id="layout">
<p:layoutUnit position="east" resizable="true" size="300" minSize="40" maxSize="300">
<p:panelMenu style="width:200px">
<p:submenu label="Create Form">
<p:menuitem value="New Form" actionListener="" icon="ui-icon-disk" />
<p:menuitem value="Current Form" actionListener="" icon="ui-icon-arrowrefresh-1-w" />
<p:menuitem value="Form Templates" actionListener="" icon="ui-icon-arrowrefresh-1-w" />
</p:submenu>
<p:submenu label="Publish Form" >
<p:menuitem value="Home" actionListener="" ajax="false" icon="ui-icon-close"/>
<p:menuitem value="Docs" actionListener="" ajax="false" icon="ui-icon-close"/>
</p:submenu>
<p:submenu label="Users Profile">
<p:menuitem value="Add New User" actionListener="" ajax="false" icon="ui-icon-close"/>
<p:menuitem value="Edit User Profile" actionListener="" ajax="false" icon="ui-icon-close"/>
<p:menuitem value="Remove Users" actionListener="" ajax="false" icon="ui-icon-close"/>
<p:menuitem value="View Users Report" actionListener="" ajax="false" icon="ui-icon-close"/>
</p:submenu>
<p:separator />
</p:panelMenu>
</p:layoutUnit>
<p:layoutUnit position="center">
<h1><font size = "6"><h:outputLabel for="createform" value="Create New Form"/></font></h1>
<hr width="98%"></hr>
<table>
<tr>
<td width="30%"><pre><h:outputLabel for="name" value="Name of the form : " /></pre></td>
<td align="left"><p:inputText id="name" value="#{questionMB.formName}" label="Name of the form">
</p:inputText>
<p:message id="formMsg" for="name" display="icon"/>
</td>
</tr>
<tr>
<td width="30%"><pre><h:outputLabel for="desc" value="Description of the form : " /></pre></td>
<td align="left"><p:inputTextarea rows="4" cols="60" value="#{questionMB.formDesc}"/>
</td>
</tr>
<tr>
<td width="30%"><pre><h:outputLabel for="question" value="Question : " /></pre></td>
<td align="left">
<p:accordionPanel>
<p:tab title="Godfather Part I">
<h:panelGrid columns="2" cellpadding="10">
<p:inputText id="question" value="#{questionMB.questionText}">
<f:validateLength minimum="5" />
<p:ajax event="blur" update="questionMsg" />
</p:inputText>
<p:message id="questionMsg" for="question" display="icon"/>
</h:panelGrid>
</p:tab>
</p:accordionPanel>
</td>
</tr>
<tr>
<td width="30%"><pre><h:outputLabel for="answer" value="Answer Type : " /></pre></td>
<td align="center">
<h:panelGrid columns="2" rows="1" style="margin-bottom:10px" cellpadding="5">
<p:selectOneRadio id="options" value="#{questionMB.answerType}">
<f:selectItem itemLabel="Text field" itemValue="Text field" />
<f:selectItem itemLabel="Combo box" itemValue="Combo box" />
<f:selectItem itemLabel="Radio button" itemValue="Radio button" />
<f:selectItem itemLabel="Check box" itemValue="Check box" />
<f:selectItem itemLabel="Date box" itemValue="Date box" />
<f:selectItem itemLabel="Y/N Button" itemValue="Y/N Button" />
</p:selectOneRadio>
</h:panelGrid>
</td>
</tr>
<tr></tr><tr></tr><tr></tr>
<tr>
<td></td><td></td>
<td><p:commandButton id="addNewQuestion" value="Add New Question" action="#{questionMB.addNewQuestion}" ajax="true"/>
</td>
</tr>
<tr>
<td></td><td></td>
<td><p:commandButton id="addQuestion" value="Save" action="#{questionMB.addQuestion}" ajax="true"/>
<p:commandButton id="submitQuestion" value="Submit" action="#{questionMB.saveandsubmitForm}" ajax="false"/></td>
</tr>
</table>
</p:layoutUnit>
</p:layout>
</h:form>
</h:body>
</html>