起初是jsp中红色感叹号，报javax.servlet.jsp.jspException can not resolve a type
我加入了jsp-api.jar报后，就报图片中的空指针异常了
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
5iMXM
src="${pageContext.request.contextPath}/ui_topUI.action">
src="${pageContext.request.contextPath}/ui_leftUI.action">
src="${pageContext.request.contextPath}/ui_rightUI">
src="${pageContext.request.contextPath}/ui_bottomUI.action">
