Session过期后自动跳转到登录页面

最近研究如果用原生的Filter来判别session存在否或者过期否。来跳转到的页面实例，下载来展示代码。

因为顾虑器是每次请求能会进入的，所以可以设置了，进行拦截判断

1.配置web.xml

	<filter>
		<filter-name>BackEndFilter</filter-name>
		<filter-class>com.sun.BackFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>BackFilter</filter-name>
		<url-pattern>/backend/issues/*</url-pattern>
		<url-pattern>/backend/repairmen/*</url-pattern>
		<url-pattern>/backend/payment/*</url-pattern>
	</filter-mapping>

 2.新建BackFilter类，实现Filter接口。

package com.xyt.backend;

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 javax.servlet.http.HttpSession;

import com.xyt.common.Logging;
import com.xyt.common.RedisClient;
import com.xyt.jdbc.entity.Admin;

/**
 * 后台管理系统登录拦截器
 */
public class BackFilter implements Filter {

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

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpSession sess = ((HttpServletRequest)request).getSession();
		String ad = sess.getAttribute("admin");
		if(ad==null ){
			((HttpServletResponse)response).sendRedirect(((HttpServletRequest)request).getContextPath()+"//login");
		}else{
			chain.doFilter(request, response);
		}
	}

	@Override
	public void destroy() {
		//useless
	}

}