loginfilter.java

购物车系统

package com.estore.web.filter;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class LoginFilter extends HttpFilter
{  
  public void doFilter(HttpServletRequest request, 
                        HttpServletResponse response, 
                          FilterChain chain)
                           throws ServletException, IOException
  {
    String path = request.getServletPath();
    if(path.startsWith("/login"))
    {
      chain.doFilter(request, response);
      return;
    }
    
    HttpSession session = request.getSession(false);
    if(session == null)
    {
      response.sendRedirect("/myapp/login.html");
      return;
    }
    
    if(session.getAttribute("userName") == null)
    {
      response.sendRedirect("/myapp/login.html");
      return;
    }
    
    chain.doFilter(request, response);
  }  
}