cookie的使用

 

效果截图：

 

 再次登录：

 servlet代码：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset =utf-8" );
        PrintWriter out = response.getWriter();//创建输出流
        String UserName = request.getParameter("username");//获取输入的信息
        String Pswd = request.getParameter("password");
        String getNull = request.getParameter("checkbox");
        Cookie[] cookies = request.getCookies();
        if(cookies!=null)
        {
            for (Cookie cookie : cookies) {//遍历cookie
                String cookname = cookie.getName();
                if(cookname.equals("UserName"))
                {
                    UserName = cookie.getValue();
                     
                }
                if(cookname.equals("Pswd"))
                {
                    Pswd = cookie.getValue();
                }  
                getNull="0";
            }
        }
        if(UserName.equals("tom")&&Pswd.equals("123")&&getNull.equals("1"))//判断是否正确和是否勾选自动登陆
        {
            Cookie cookie= new Cookie("UserName", UserName);//建立cookie
            Cookie cookie2 = new  Cookie("Pswd",Pswd);
            cookie.setMaxAge(2592000);//设置cookie的生存时间
            cookie2.setMaxAge(2592000);
            response.addCookie(cookie);
            response.addCookie(cookie2);//将建立的cookie存入
            out.println("<p>欢迎"+UserName+",你已登录成功!</P>");
        }
        else if(UserName.equals("tom")&&Pswd.equals("123")&&getNull.equals("0")){
            out.println("<p>欢迎"+UserName+",你已登录成功!</P>");
            out.println("<p>你已记住密码</p>");
        }
        else if(UserName.equals("tom")&&Pswd.equals("123")){
            out.println("<p>欢迎"+UserName+",你已登录成功!</P>");
        }
        else {
            out.println("用户名或者密码错误");
        }
    }

Filter代码：

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        // TODO Auto-generated method stub
        // place your code here

        // pass the request along the filter chain
         // 将请求转换成HttpServletRequest请求
        HttpServletRequest httpRequest=(HttpServletRequest)request;
        // 将响应转换成HttpServletResponse响应
        HttpServletResponse httpResponse = (HttpServletResponse)response;
        //截取用户的请求地址
        String from =httpRequest.getServletPath();
        if(from.equals("/index.html")) {
            //获取本站在客户端上保留的所有的cookie
            Cookie[] cookies=httpRequest.getCookies();
            if(cookies!=null) {
                //遍历cookie数组
                
                httpResponse.sendRedirect("Login");
            }            
            // 放行请求
            chain.doFilter(request, response);
        }
        else {
            chain.doFilter(request, response);
        }
    }