标签：数据 center etc obj writer png 请求转发 sele through
1、使用Cookie实现的登录的不足：
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Connection con=null; login log= null; String account=request.getParameter("username");//获得表单数据只在此Servlet起作用 String password=request.getParameter("password"); Cookie cookie=new Cookie(account,password); cookie.setPath("/Servlet_login_war_exploded/cookie"); cookie.setMaxAge(3*24*3600); response.addCookie(cookie); try { con=C3p0Utils.getConnection(); QueryRunner qr = new QueryRunner(); String sql = "Select * from login where account=? and password=?"; Object[] select = {account,password}; log = qr.query(con, sql, new BeanHandler<login>((login.class)), select); if(log!=null){ response.getWriter().write("nihao"+account); } else{ response.getWriter().write("wrong"); } } catch (SQLException e) { throw new RuntimeException(e); } }
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html; charset=utf-8");//设置浏览器编码格式 response.getWriter().write("<html>"); response.getWriter().write("<head>"); response.getWriter().write("<title>"); response.getWriter().write("Login"); response.getWriter().write("</title>"); response.getWriter().write("</head>"); response.getWriter().write("<body bgcolor=\"aqua\">"); response.getWriter().write("<center>"); response.getWriter().write("<h3>"); response.getWriter().write("欢迎你"+request.getParameter("account")); response.getWriter().write("</h3>"); response.getWriter().write("</center>"); response.getWriter().write("</body>"); }
使用Cookie虽然实现了三天免登陆的基础功能，但是，如果在用Cookie登录成功后需要重定向到另外一个Cookie时，request获取的值在重定向的Servlet中已经不再起作用了。访问的结果只能是空值。
2、使用Session的请求共享功能，实现在不同的Servlet跳转过程中依旧能够通过request获得用户信息。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html; charset=utf-8");//设置浏览器编码格式 Cookie[] cookies=request.getCookies(); Connection con=null; login log= null; int successNum=0; try { con= C3p0Utils.getConnection(); QueryRunner qr = new QueryRunner(); String sql = "Select * from login"; List<login> list = qr.query(con, sql, new BeanListHandler<login>((login.class))); if(cookies!=null) {//验证数据库中是否有与Cookie对应的用户 for (int i = 0; i < list.size(); i++) { log= list.get(i); for (Cookie cookie : cookies) { if((log.getAccount().equals(cookie.getName()))&&(log.getPassword().equals(cookie.getValue()))){ HttpSession httpSession=request.getSession(); httpSession.setAttribute("login",log); successNum++; } } } if(successNum>=1){ response.sendRedirect("/Servlet_login_war_exploded/main");//重定向 } else{ request.getRequestDispatcher("page").forward(request,response); } } else{ request.getRequestDispatcher("page").forward(request,response);//请求转发 } } catch (SQLException e) { throw new RuntimeException(e); } }
在通过Cookie登录成功后，创建了Session，对Session进行了赋值，而在重定向到MainServlet后，可以冲Session中获取值。虽然在不同的Servlet中，是不同的请求，但是依旧能够通过Session获取值。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { login log= (login) request.getSession().getAttribute("login"); response.setContentType("text/html; charset=utf-8");//设置浏览器编码格式 response.getWriter().write("<html>"); response.getWriter().write("<head>"); response.getWriter().write("<title>"); response.getWriter().write("Login"); response.getWriter().write("</title>"); response.getWriter().write("</head>"); response.getWriter().write("<body bgcolor=\"aqua\">"); response.getWriter().write("<center>"); response.getWriter().write("<h3>"); response.getWriter().write("欢迎你"+log.getAccount()); response.getWriter().write("</h3>"); response.getWriter().write("</center>"); response.getWriter().write("</body>"); }
标签：数据 center etc obj writer png 请求转发 sele through
原文地址：https://www.cnblogs.com/zhai1997/p/11559989.html
