java实现用户自动登录

<c:choose>

  <c:when test="${empty sessionScope.name}">
    <form name="x" method="post" action="<c:url value='/LoginServlet'/>">
      Name:<input type="text" name="name"/><br/>
      auto:
      <input type="radio" name="auto" value="-1">不自动登录
      <br/>
      <input type="radio" name="auto" value="1">1天<br/>
      <input type="radio" name="auto" value="7">1周<br/>
      <input type="submit"/>
    </form>
  </c:when>
  <c:otherwise>

    你已经登录了:${name}<br/>
    <a href="<c:url value='/LoginServlet'/>">退出</a>
  </c:otherwise>

</c:choose>

public void doPost(HttpServletRequest request, HttpServletResponse response)

      throws ServletException, IOException {
    //接收用户姓名
    String name = request.getParameter("name");
    String auto = request.getParameter("auto");
    //将用户信息放到session
    request.getSession().setAttribute("name",name);
    //判断auto是否是-1
    if(!auto.equals("-1")){
      int day = Integer.parseInt(auto);//1|7
      int seconds = 60*60*24*day;
      //声明cookie
      Cookie c = new Cookie("autoLogin",name);
      c.setMaxAge(seconds);
      c.setPath(request.getContextPath());
      //保存cookie
      response.addCookie(c);
     

    }

  }

public void doFilter(ServletRequest request, ServletResponse response,

    FilterChain chain) throws IOException, ServletException {
    //在这儿读取cookie
    HttpServletRequest req = (HttpServletRequest) request;
    //获取所的有cookie
    Cookie[] cs = req.getCookies();
    if(cs!=null){
      for(Cookie c:cs){
       if(c.getName().equals("autoLogin")){//如果存在自动登录的cookie
         String value = c.getValue();//用户名称

         //登录成功是指
         req.getSession().setAttribute("name", value);
         break;

       }

      }

    }

    //不管是否自动登录成

    chain.doFilter(request, response);

  }

<filter>

  <filter-name>auto</filter-name>
  <filter-class>cn.itcast.filter.AutoFilter</filter-class>
  </filter>
  <filter-mapping>
  <filter-name>auto</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>

System.err.println("用户退出");

    //删除整个session
    request.getSession().invalidate();
    Cookie c = new Cookie("autoLogin", "ddd");
    c.setMaxAge(0);
    c.setPath(request.getContextPath());
    response.addCookie(c);
//  request.getSession().removeAttribute("name");
    response.sendRedirect(request.getContextPath()+"/index.jsp");

package cn.hongxin.filter;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


public class LoginFilter implements Filter{

  public void init(FilterConfig filterConfig) throws ServletException {

  }
  public void doFilter(ServletRequest request, ServletResponse response,
      FilterChain chain) throws IOException, ServletException {
    //将request强转成htt...
    HttpServletRequest req = (HttpServletRequest) request;
    //获取session
    HttpSession ss = req.getSession();
    //从session中获取user
    if(ss.getAttribute("user")==null){
      System.err.println("你还没有登录");
      req.getSession().setAttribute("msg", "请你先登录");

      //重定向到登录
      HttpServletResponse resp = (HttpServletResponse) response;
      resp.sendRedirect(req.getContextPath()+"/index.jsp");[W2] 
    }else{

      //放行
      chain.doFilter(request, response);

    }

  }

  public void destroy() {

  }

}

<filter>

  <filter-name>login</filter-name>
  <filter-class>cn.itcast.filter.LoginFilter</filter-class>
 </filter>
 <filter-mapping>
  <filter-name>login</filter-name>
  <url-pattern>/jsps/*</url-pattern>
  <url-pattern>/views/*</url-pattern>
 </filter-mapping>