jsp 页面引用原理

方法
例1.<%@ include file="/publish/class_<%=cls.getId()%>.txt" %>

例2.<jsp:include page="/publish/class_<%=cls.getId()%>.txt"></jsp:include>

例3.<c:import url="/publish/class_<%=cls.getId()%>.txt" />


<%@ include 在编译时读入 file文件 (所以文件名不支持动态)，生成一个servlet
若例1 则直接找/publish/class_<%=cls.getId()%>.txt 页面 报错file not found

<c:import 与 <jsp:include 行为相同
编译时值引用文件名(文件名可以是动态的)，当请求时，才读include页面信息相当于Dispatcher

但要注意 ：有时使用例2，例3时 回报错
interpolated runtime values are forbidden by the JSP spec at '.
./../publish/class_<%=cls.getId()%>.txt'

使用一下写法
1.
<%
String pp="/publish/class_"+cls.getId()+".txt";
%>

<jsp:include page="<%=pp%>"></jsp:include>
<c:import url="<%=pp%>" />

或
2.
<jsp:include page="/publish/class_${cls.id}.txt"></jsp:include>

<c:import url="/publish/class_${cls.id}.txt" />