普通管理员也可以添加用户，按照问答里相似的问题修改之后还是不行

package com.imooc.servlet;

import com.imooc.db.CourseDaoImpl;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import java.util.Map;

/**
 * 验证码的Servlet
 */
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //验证码部分
        //页面用户输入的验证码
        String inputCode=req.getParameter("code");
        //服务器端生成的验证码
        String code=(String)req.getSession().getAttribute("Code");
        if(!code.equalsIgnoreCase(inputCode)){
            resp.setContentType("text/html;charset=gb2312");
            PrintWriter out = resp.getWriter();
            out.print("<script language='javascript'>alert('验证码错误');window.location.href='index.jsp';</script>");
            return;
        }

             //用户名与密码
               String username=req.getParameter("username");
               String password=req.getParameter("password");
        if((username!=null&&!username.equals(""))&&(password!=null&&!password.equals(""))){
            if(username.equals("imooc")&&password.equals("imooc")){
                //将用户名存到session中
                req.getSession().setAttribute("username",username);
                req.getRequestDispatcher("server.jsp?flag=1").forward(req,resp);
                return;

            }
        }
                //获取用户表
                 CourseDaoImpl courseDaoImpl=new CourseDaoImpl();
                 List<Map<String,Object>> userList=courseDaoImpl.getUsersTable();
                 for(Map<String,Object> map:userList){
                     //判断用户名是否正确
                     if(username.equals(map.get("username")));{
                         if(password.equals(map.get("password"))){

                             resp.sendRedirect("server.jsp");

                         }else{
                             //用户名或密码错误
                             req.setAttribute("msg","用户名或密码错误");
                             req.getRequestDispatcher("index.jsp").forward(req,resp);
                             return;
                         }
                     }
                }




    }
}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
            + "/" + request.getServletContext().getContextPath();
%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html>
<html>
<head>
    <base href="<%=basePath%>">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>课程后台管理系统</title>
</head>
<frameset rows="20%,*">
    <frame src="./top.jsp"></frame>
    <frameset cols="15%,*">
        <frame src="./left.jsp"></frame>
        <frame name="main"></frame>
    </frameset>
</frameset>
</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
            + "/" + request.getServletContext().getContextPath();
%>
<!DOCTYPE html>
<html>
<head>
    <base href="<%=basePath%>">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>登录页面</title>
    <style type="text/css">
        .c1{
            width:300px;
            cursor:pointer;
        }
        .c2{
            width:300px;
            padding-left: 30px;
        }
    </style>
</head>
<body>
<c:choose>
    <c:when test="${flag==1 }">
        <div class="c1">
            <h3 onclick="show1()">用户管理</h3>
            <div class="c2" id="menu1" style="display:none;">
                <p><a href="<%=basePath%>/addUser.jsp" target="main">添加管理员</a></p>
                <p><a href="<%=basePath%>/SelectUserServlet" target="main">查询管理员</a></p>
            </div>
        </div>
    </c:when>
    <c:otherwise>
        <h3>用户管理</h3>
    </c:otherwise>
</c:choose>
<div class="c1">
    <h3 onclick="show2()">课程管理</h3>
    <div class="c2" id="menu2" style="display:none;">
        <p><a href="<%=basePath%>/addCourse.jsp" target="main">课程添加</a></p>
        <p><a href="<%=basePath%>/courseImport.jsp" target="main">课程批量导入(Excel)</a></p>
        <p><a href="<%=basePath%>/ExportCourseServlet" target="main">课程导出</a></p>
        <p><a href="<%=basePath%>/GetCourseServlet" target="main">课程查询</a></p>
    </div>
</div>
<script type="text/javascript">
    function show1(){
        var menu = document.getElementById("menu1");
        var displayStyle = menu.style.display;
        if(displayStyle=="none"){
            menu.style.display="block";
        }else{
            menu.style.display="none";
        }
    }
    function show2(){
        var menu = document.getElementById("menu2");
        var displayStyle = menu.style.display;
        if(displayStyle=="none"){
            menu.style.display="block";
        }else{
            menu.style.display="none";
        }
    }
</script>
</body>
</html>

精慕门6573819 2018-11-29

源自：项目：商品展示及购物车 5-3 作业题