ifram框架session过期时，导致框架内部嵌套显示顶层框架的解决

package com.aowin.filter;


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


import com.aowin.model.User;


public class LogFilter implements Filter
{


	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException
	{
		HttpServletRequest req=(HttpServletRequest)request;
		HttpServletResponse resp=(HttpServletResponse)response;
		
		User user=(User) req.getSession().getAttribute("user");
		String uri=req.getRequestURI();
		String path=req.getContextPath();
		if(user==null&&!uri.endsWith("login.jsp"))
		{
			//resp.sendRedirect(path+"/login.jsp");
			resp.setContentType("text/html;charset=UTF-8");
	        resp.getWriter().println("");
		}
		else
			chain.doFilter(request, response);
	}


	@Override
	public void init(FilterConfig filterConfig) throws ServletException
	{
		
	}


	@Override
	public void destroy()
	{


	}


}