<! -- configure session timeout in minutes -- >
	<session-config>
		<session-timeout>180</session-timeout>
	</session-config>

package com.wzxy.nc.util;
import com.opensymphony.xwork2.ActionContext;
import com.wzxy.nc.entity.SysUser;
public class HttpSessionUtil{
	@SuppressWarnings("unchecked")
	public static <T> T getObject(String key,T t){
		return (T)ActionContext.getContext().getSession().get(key);
	}
	public static void put(String key,Object value){
		ActionContext.getContext().getSession().put(key, value);
	}
	public static SysUser getCurrentUser(){
     // Sysconstant.login'user is a string, that is, the key where you put the session user information
	return (SysUser) ActionContext.getContext().getSession().get(SysConstant.LOGIN_USER);
	}
}

package com.wzxy.nc.interceptor;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
import com.wzxy.nc.entity.SysUser;
import com.wzxy.nc.util.HttpSessionUtil;
public class LoginInterceptor extends AbstractInterceptor {
	private static final long serialVersionUID = 7860956813431996758L;
	private static final Logger logger = LoggerFactory.getLogger(LoginInterceptor.class);
	@Override
	public String intercept(ActionInvocation ai) throws Exception {
		logger.info("************** Landing interceptor **************");	
		// Get the requested URL
		String url = ServletActionContext.getRequest().getRequestURL().toString();
		HttpServletResponse response = ServletActionContext.getResponse();
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Cache-Control", "no-store");
		response.setDateHeader("Expires", 0);
		SysUser user = null;
		// Direct release of login and logout requests without interception
		if (url.indexOf("login") != -1 || url.indexOf("logout") != -1) {
			return ai.invoke();
		} else {
			// Verify that the Session expires
			if (!ServletActionContext.getRequest().isRequestedSessionIdValid()) {
				// Session expiration, turn to session expiration prompt page, and finally jump to login page
				return "relogin";
			} else {
				user = HttpSessionUtil.getCurrentUser();
				// Verify that you are logged in
				if (user == null) {
					logger.info("Not yet logged in");
					// Not logged in, jump to login page
					return "relogin";
				} else {
					return ai.invoke();
				}
			}
		}
	}	
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
	<package name="default" namespace="/" extends="json-default,struts-default">
        <interceptors>
            <interceptor name="loginInterceptor" class="com.wzxy.nc.interceptor.LoginInterceptor"/>
            <interceptor-stack name="loginStack">
                <interceptor-ref name="loginInterceptor" />
                <interceptor-ref name="defaultStack" />
            </interceptor-stack>
        </interceptors>   
        <global-results>
            <result name="relogin" type="redirect">/login.jsp</result>
        </global-results>
		<action name="*_*" method="{2}" class="com.wzxy.nc.controller.{1}Controller">	
			<result name="success">${forwardPage}</result>
			<result name="error">${forwardPage}</result>
			<result name="redt" type="redirect">${forwardPage}</result>
			<result name="download" type="stream">
				<!-- Specify the type of download file -->
				<param name="contentType">application/octet-stream</param>
				<!-- Specify where to download files -->
				<param name="inputName">fileInputStream</param>
				<param name="contentDisposition">attachement;filename=${downFileName}</param>
				<!-- Specifies the buffer size of the download file -->
				<param name="bufferSize">4096</param>
			</result>
			<result name="json" type="json">
				<param name="root">dataMap</param>
			</result>
			<interceptor-ref name="loginStack" />
		</action>
	</package>
</struts>    

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