jsp页面报javax.servlet.jsp.PageContext cannot be resolved to a type：

某个JSP内容如下，在IDE中会出现JSP Problem如标题所示的javax.servlet.jsp.PageContext cannot be resolved to a type：

<c:if test="${not pageContext.request.secure}">
<div id="msg" class="securityerrors">
<h2>Non-secure Connection</h2>
<p>You are currently accessing CAS over a non-secure connection.  Single Sign On WILL NOT WORK.  In order to have single sign on work, you MUST log in over HTTPS.</p>
</div>
</c:if>

方法一：这是缺少缺少jsp-api.jar 

               导入这个包即可

方法二：若项目用Maven管理最好不要用方法一：而是用maven update项目或者从命令行更新

              1、在开发工具点项目鼠标右键 选Properties 找到项目路径并复制

               2、win+R cmd 在控制台写cd 并粘贴项目路径

               3、mvn clean package更新