用过滤器Filter判断用户是否登陆

用过滤器Filter判断用户是否登陆

WEB.XML 

<!-- 用户session的 键   sessionKEY -->
  <context-param>
    <param-name>userSessionKey</param-name>
    <param-value>USERSESSIONKEY</param-value>
  </context-param>
  <!-- 重定向的页面 -->
  <context-param>
    <param-name>rediretPage</param-name>
    <param-value>/u_member/Login.jsp</param-value>
  </context-param>
  <!-- 不需要过滤的页面 -->
  <context-param>
    <param-name>uncheckUrls</param-name>
    <param-value>/u_member/insert.jsp,/u_member/Login.jsp</param-value>
  </context-param>

Filter 过滤器代码

package go.onlineShop.filter;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet Filter implementation class IsLoginFilter
 * 判断是否登陆过滤器
 */
@WebFilter("/u_member")
public class IsLoginFilter implements Filter {

    //从xml中取值
    String uncheckUrls =null;
    String userSessionKey=null;
    String rediretPage=null;
    /**
     * Default constructor.
     */
    public IsLoginFilter() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Filter#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
     */
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        // TODO Auto-generated method stub
        //1.得到访问路径
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)res;
        String reqUrl = request.getRequestURL().toString();
        String reqURI = request.getRequestURI();

        String servletPath = request.getServletPath();

    //  String[] uncheckUrl = uncheckUrls.split(",");
        List<String> urls = Arrays.asList(uncheckUrls.split(","));
        //2.如果是属于不需要过滤的地址就直接  放行  方法结束
        if(urls.contains(servletPath)){
            chain.doFilter(request, response);
            return;
        }

        //3.从session中获取sessionKey对应的值；若不存在  则跳转到登陆页面

        Object user = request.getSession().getAttribute(userSessionKey);
        if(user==null){
            request.getRequestDispatcher(rediretPage).forward(request, response);
            return;
        }
        //4若存在 则放行；
        chain.doFilter(request, response);
    }

    /**
     * @see Filter#init(FilterConfig)
     */
    public void init(FilterConfig fConfig) throws ServletException {
        rediretPage=fConfig.getServletContext().getInitParameter("rediretPage");
        uncheckUrls=fConfig.getServletContext().getInitParameter("uncheckUrls");
        userSessionKey=fConfig.getServletContext().getInitParameter("userSessionKey");
    }

}

Login页面

参考：

用过滤器Filter判断用户是否登陆 - CSDN博客
http://blog.csdn.net/u010634066/article/details/38769577