session超时跳转

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
* 用于检测用户是否登陆的过滤器，如果未登录或超时，则重定向到指的登录页面<p>
*/
public class CheckLoginFilter
implements Filter
{


public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;

HttpSession session = request.getSession();
//用户超时或没有登陆时跳转到登陆页面
if(session.Attribute("username")==null||session.isnew())
{
response.sendRedirect("登陆页面");
}

filterChain.doFilter(servletRequest, servletResponse);
}

public void destroy()
{

}


public void init(FilterConfig filterConfig) throws ServletException
{

}
}