Cookie实例——记住用户名-蒲公英云

Cookie实例——记住用户名

小鱼儿 2022-06-18 09:20 243阅读 0赞

1.简单流程图

在网站登录中经常会有记住用户名这一操作，利用Cookie便可以实现，其间单的流程如下

Center

2.利用代码实现

新建一个Login的Servelet，写入下面代码

public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        String userName ="";
        String checked = "";
        //得到客户端保存的Cookie数据
        Cookie[] cookies = request.getCookies();
        for (int i = 0;cookies!=null && i < cookies.length; i++) {
            if("userName".equals(cookies[i].getName())){
                userName = cookies[i].getValue();
                checked = "checked='checked'";
            }
        }
        out.write("<form action='"+request.getContextPath()+"/servlet/DoLogin' method='post'>");
        out.write("用户名：<input type='text' name='userName' value='"+userName+"'/><br/>");
        out.write("密码：<input type='password' name='pwd'/><br/>");
        out.write("<input type='checkbox' name='remember' "+checked+" />记住用户名<br/>");
        out.write("<input type='submit' value='登录'/><br/>");
        out.write("</form>");
    }

再新建一个DoLogin方法

public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        //获取表单数据
        String userName = request.getParameter("userName");
        String pwd = request.getParameter("pwd");
        String remember = request.getParameter("remember");
        Cookie ck = new Cookie("userName", userName);
        ck.setPath("/");
        //处理业务逻辑
        //分发转向
        if("tom".equals(userName)&&"123".equals(pwd)){
            if(remember!=null){
                ck.setMaxAge(Integer.MAX_VALUE);//设置Cookie的有效保存时间
            }else{
                ck.setMaxAge(0);//删除 Cookie
            }
            response.addCookie(ck);//将Cookie写回到客户端
            out.write("登录成功！");
        }else{
            out.write("登录失败！");
            //设置2秒跳到重新登录
            response.setHeader("refresh", "2;url="+request.getContextPath()+"/servlet/Login");
        }