Cookie的应用——Servlet实现三天免登录_html-js-css

概述1、工程结构： 2、Servlet的运用：（1）登录界面： protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html; cha

1、工程结构：

2、Servlet的运用：

（1）登录界面：

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("登录");        response.getWriter().write("</h3>");        response.getWriter().write("<form action=\"/Servlet_login_war_exploded/login\" method=\"get\">");        response.getWriter().write("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;用户名：<input type=\"text\" name=\"username\" size=\"12\"><br>");        response.getWriter().write("密&nbsp;&nbsp;码 ：<input type=\"password\" name=\"password\" size=\"6\" ><br><br>");        response.getWriter().write("<input type=\"submit\" value=\"登录\">");        response.getWriter().write("<input type=\"reset\" value=\"取消\">");        response.getWriter().write("</form>");        response.getWriter().write("</center>");        response.getWriter().write("</body>");        response.getWriter().write("</HTML>");    }

（2）LogServlet实现数据库和表单数据的连接，如果在数据库中有对应的用户登录信息则登录成功。如果是第一次登录，还需要建立cookie，以便下次登陆的时候能够直接读取cookie中的信息，不用再手动输入自己的信息。

protected voID doGet(httpServletRequest request,IOException {        Connection con=null;        login log= null;        String account=request.getParameter("username");//获得表单数据        String password=request.getParameter("password");        cookie cookie=new cookie(account,password);        cookie.setPath("/Servlet_login_war_exploded/cookie");        cookie.setMaxAge(3*24*3600);//三天        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);        }    }

在响应中，存在cookie信息和cookie的过期时间。

（3）查询cookie是否存在，如果存在，再与数据库中的信息进行对比（只有cookie是不行的，防止用户已经对账户注销，即数据库中已经没有了用户的信息，而使用cookie进行登录显然是不合理的）

protected voID doGet(httpServletRequest request,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,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()))){                           successNum++;                        }                }                }                if(successNum>=1){                    response.getWriter().write("Successful login with cookie!");                }                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);        }    }