j2ee系统登录过滤

web.xml

	<!-- For Security --> 

	<filter>
		<filter-name>ActionFilter</filter-name>
		<filter-class>com.fg.security.ActionFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>ActionFilter</filter-name>
		<url-pattern>*.do</url-pattern>
	</filter-mapping>
		<filter-mapping>
		<filter-name>ActionFilter</filter-name>
		<url-pattern>*.jsp</url-pattern>
	</filter-mapping>

ActionFilter.java

/**
 * 
 */
package com.fg.security;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
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.fg.common.CommLogger;
import com.fg.common.Constant;
import com.fg.common.FgObject;
import com.fg.common.exception.ExceptionLogger;
import com.fg.urp.business.UserKeyService;

/**
 * @author Agui
 * @date 2005-7-22
 */
public class ActionFilter extends FgObject implements Filter {

	public void init(FilterConfig config) {
		//
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) {
		String taskUiid=null;
		String uiid=null;
		try {

			CommLogger.debug(getClass()," *** In ActionFilter *** ");

			HttpServletRequest req = (HttpServletRequest) request;
			HttpServletResponse rep = (HttpServletResponse) response;

			// Get user information
			HttpSession session = req.getSession(true);
			//从session中提取用户的session
			UserKeyService user = (UserKeyService) session
					.getAttribute(Constant.SESSION_USER);

			CommLogger.debug(getClass(),"     URI: " + req.getRequestURI());
			
			//如果不等于登陆页面
            if(!req.getRequestURI().equals("/msp/login.do")){
			//if(req.getQueryString()!=null) rep.sendRedirect(req.getContextPath()+"/error.jsp");
            }
            //user == null 或者 没有登陆
			if (!(user!=null&&user.isLogin())) {
				String uri = req.getRequestURI();
				//如果不是登录页面
				if (!uri.equalsIgnoreCase(req.getContextPath() + "/login.do")) {
					CommLogger.debug(getClass(),"     Action Stop!");
					rep.sendRedirect(req.getContextPath() + "/login.do");
				} else {
					chain.doFilter(request, response);
				}
			} else {
				//user ！=null and 登陆了
				  if(user==null) rep.sendRedirect(req.getContextPath() + "/login.do");
				  if(req.getParameter("Uiid")!=null) uiid=req.getParameter("Uiid");
				  if(req.getParameter("taskUiid")!=null) taskUiid=req.getParameter("taskUiid");
				  
				  chain.doFilter(request, response);
			}

			CommLogger.debug(getClass()," *** Out ActionFilter *** ");

		} catch (Exception e) {
			ExceptionLogger.logErrorMsg(e,getClass(),null);
		} catch (Throwable t) {
			t.printStackTrace();
		}
	}

	public void destroy() {
		//
	}
}