Java Web实战项目-六

上回已经搞定了登陆的问题，那么登陆之后页面就要转到首页，并将原来登陆字样改为已经登陆的用户名字样，这里主要用到的是session类。

1. 改写LoginServlet
   在登陆验证成功后将session里的用户名填入request，并执行转发：

   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       
       String username = request.getParameter("username").trim();
       String password = request.getParameter("password").trim();
   
           
               
               String resource = "mybatis-config.xml";
               InputStream inputStream = Resources.getResourceAsStream(resource);
               SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
                       .build(inputStream);
               SqlSession session=sqlSessionFactory.openSession();
                Map<String,Object> params = new HashMap<>();
                params.put("username", username);
                   params.put("password", password);
                   List<User> us = session.selectList("getPassword",username);
                   User user = us.get(0);
                   if(user.getPassword().equals(password)){
                       request.getSession().setAttribute("n", username);
                       request.getRequestDispatcher("/index.jsp").forward(request,response);
                   }
           
           
   
       }

2. 改写Header.jsp
   使用jsp的taglib自定义标签，要先引用相关的包

   <%@ page language="java" contentType="text/html; charset=UTF-8"
       pageEncoding="UTF-8"%>
       <%@taglib uri="http://java.sun.com/jsp/jstl/core"  prefix="c"%>
           <div class="col-md-12 column" >
               <ul class="nav nav-tabs">
                   <li style="font-size:20px;">
                        <a href="index.jsp">首页</a>
                   </li>
                      <c:choose>
                       <c:when  test="${empty sessionScope.n}">
                   <li style="font-size:20px;">
                        <a href="login.jsp">登陆</a>
                   </li>
                   </c:when>
           <c:otherwise>
           <li style="font-size:20px;">
           <a href="javascript:void(0)">欢迎您，${sessionScope.n}</a>
           </li></c:otherwise></c:choose>
                   <li style="font-size:20px;">
                        <a href="#">商店</a>
                   </li>
                   
               </ul>
           </div>