记住用户名-Cookie应用实例
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
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");
- }
得到的结果为：
登录后显示成功登录
再次访问时，“用户名”和“登录用户名”均自动填充
3.总结
以上便是利用Cookie的知识来实现的一个网站经常拥有的功能，如果有错误，请提出，谢谢。