filter完成自动登录的代码实现

1,定义个javabean类,按照账号和密码设置变量定义好user类.

2,建一个servlet的包,定义一个处理登录界面的逻辑servlet,然后按照步骤编写代码

     protected
voiddoGet(HttpServletRequest
request,HttpServletResponse response)
throws ServletException, IOException {

           //获取提交的数据，组织为 JavaBean

           Useruser =
newUser();

           Stringusername =
request.getParameter("username");

           Stringpassword =
request.getParameter("password");

           user.setUsername(username);

           user.setPassword(password);

           //查询数据库,当前直接认为用户合法

           //判断是否设置为自动登陆

           Stringauto =
request.getParameter("auto");

           //如果是，那么将账号密码设置进 Cookie

           Cookiec =
newCookie("user",username +
"@"+ password);

           if("yes".equals(auto)){

                 c.setMaxAge(60 * 60 * 24 * 7);

           }else {

                 c.setMaxAge(0);

           }

           response.addCookie(c);

          

           //将用户设置进 session

           //request.setAttribute("user", user);

           request.getSession().setAttribute("user",
user);

           //请求转发到 index.jsp

           request.getRequestDispatcher("/index.jsp").forward(request,
response);

      }

这里index.jsp就是默认的首页登录界面.auto是在输入账号密码的jsp里设置的input的属性,

4000
  <input
type="checkbox"name="auto"
value="yes">自动登录

                                                 
</label>     <label>
<input

                                                       
type="checkbox"> 记住用户名

3,创建过滤器

      public
voiddoFilter(ServletRequest
request,ServletResponse response, FilterChain
chain) throwsIOException, ServletException {

           Useruser =
null;

           //强转换来获取request.Cookie

           HttpServletRequestr = (HttpServletRequest)request;

           //获取cookie

           Cookie[]cs =
r.getCookies();

           //判断cookie是否存在,也就是判断之前是否已经登陆过一次网页

           if(cs!=null){

                 for (Cookie
c: cs) {

                      if("user".equals(c.getName())){

                     
//获取遍历后c的值(账号和密码)根据@来进行切割

                      String[]arr =
c.getValue().split("@");

                     
//arr[0]是账号arr[1]是密码

                      user.setPassword(arr[1]);

                     
user.setUsername(arr[0]);

                     
//讲获取到的值传给session,进行下一步的页面访问

                     
r.getSession().setAttribute("user",
user);

                      }

                 }

           }

           //放行语句

           chain.doFilter(request,response);

      }

这样再form表单里设置好属性,把获取到网页输入的账号的标签里设置成属性name=”username”, 把获取到网页输入的密码的标签里设置属性name=”password”

然后就可以run as进行调试了.