filter实现登陆拦截

package com.ucit.filter;

import java.io.IOException;
import java.util.ArrayList;
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;

import com.ucit.struts.action.LoginAction;

public class TuserCheckFilter implements Filter {

    public void destroy() {
        // TODO Auto-generated method stub

    }

    static ArrayList<HttpSession> tusers = LoginAction.tusers;

    public void doFilter(ServletRequest arg0, ServletResponse arg1,
            FilterChain arg2) throws IOException, ServletException {
        // 当前SESSION不在Tusers里的时候，就让他跳到登陆页面

        HttpSession nowSession = ((HttpServletRequest) arg0).getSession();

        boolean in = false;
        for (int i = 0; i < tusers.size(); i++) {
            if (nowSession == tusers.get(i)) {
                in = true;
                break;
            }
        }

        if (!in) {
            if (!((HttpServletRequest) arg0).getServletPath().equals(
                    "/login.jsp"))

            {
                ((HttpServletResponse) arg1)
                        .sendRedirect("/oracleManagement/login.jsp");
            } else {
                arg2.doFilter(arg0, arg1);
            }
            ;

        } else {

            arg2.doFilter(arg0, arg1);
        }

    }

    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }

}