package uri;

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 UserLoginFilter implements Filter {
    private String redirectURI = null;// 检查路径

    public UserLoginFilter() {

    }

    public void destroy() {

    }

    public void doFilter(ServletRequest arg0, ServletResponse arg1,
            FilterChain filterChain) throws IOException, ServletException {
        // 配置参数
        HttpServletRequest request = (HttpServletRequest) arg0;
        HttpServletResponse response = (HttpServletResponse) arg1;

        // 创建会话
        HttpSession session = request.getSession();
        // 判断用户是否已经登录
        if (session.getAttribute("User") == null) {
            // 设置拦截的路径
            if (!request.getRequestURI().contains("Login")
                    || request.getRequestURI().contains("functionMenu")
                    || request.getRequestURI().contains("showFiles")) {
                // 不包含登录路径的强制跳转到登录页面
                request.getRequestDispatcher(redirectURI).forward(request,
                        response);
                return;
            }
            // 包含的就放行
            filterChain.doFilter(request, response);
            return;
        }else{
            //已登录就放行
            filterChain.doFilter(request, response);
            return;
        }

    }

    public void init(FilterConfig arg0) throws ServletException {
        redirectURI = "Loging.jsp";// 跳转页面

    }

}

//调用登录方法返回一个用户
        User empUser=new User();
        empUser=LoginDao.Login(mallID, password);
        //会话跟踪用户
        HttpSession userSession=request.getSession();
        userSession.setAttribute("User", empUser);

  <session-config>
      <session-timeout>15</session-timeout>
  </session-config>
  
  <filter>
      <filter-name>UserLoginFilter</filter-name>
    <filter-class>uri.UserLoginFilter</filter-class>
  </filter>
  <filter-mapping>
      <filter-name>UserLoginFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>