JSP权限过滤器

package com.wake.util;
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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.wake.bean.AdminUser;

/**
 * @author Administrator
 *
 */
public class PopedomControl extends HttpServlet implements Filter 
{
	private FilterConfig filterConfig;
	private static final long serialVersionUID = -4275105240038370264L;

	/*
	 * （非 Javadoc ）
	 */
	public void init(FilterConfig arg0) throws ServletException 
	{
	}
	
	/*
	 * （非 Javadoc ）
	 */
	public void doFilter(ServletRequest request, ServletResponse response,
							FilterChain filterChain)
	{
		HttpServletRequest servletRequest = (HttpServletRequest) request;
		HttpServletResponse servletResponse = (HttpServletResponse) response;
		HttpSession session = servletRequest.getSession();
		// 获取当前页面文件名
		String url = servletRequest.getRequestURI();
		url = url.substring(url.lastIndexOf("/") + 1, url.length());
		
		try 
		{
			// 排除后台不作权限控制的页面名
			String exclude= "adminlogin.action,login.jsp,Message.jsp,loginout.jsp";
			if(exclude.indexOf(url)==-1)
			{
				// 获取网站访问根目录
				String accessPath = servletRequest.getContextPath();
				// 用当前页面文件名与用户权限字符比较
				AdminUser adminuser = (AdminUser) session.getAttribute("auser");
				if (adminuser == null)
				{
					servletResponse.sendRedirect(accessPath +
												"/admin/login.jsp");
				}
				else if(adminuser.getUserPopedom().indexOf(url)==-1)
				{
					servletResponse.sendRedirect(accessPath +
												"/admin/Message.jsp");
				}
			}
		}
		catch (Exception sx) 
		{
			sx.printStackTrace();
		}
		try 
		{
			filterChain.doFilter(request, response);
		}
		catch (ServletException sx)
		{
			filterConfig.getServletContext().log(sx.getMessage());
		}
		catch (IOException iox)
		{
			filterConfig.getServletContext().log(iox.getMessage());
		}
	}
	
	public void destroy()
	{
	}
}