由于书上的例子弄不出来
自己瞎弄了个简易版的
登陆页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>My JSP 'login.jsp' starting page <% String errorMessage = request.getAttribute("errorMessage").toString(); if (errorMessage != ""){ %> <%=errorMessage %> <%} %>