session过期判断的基本思想：用户登录成功后，将用户账号信息保存在session中，然后几乎每次执行命令都要经过过滤器，过滤器检查session中是否存在账号，若不存在，
则返回登录页面，反之正常执行。
1、web.xml中添加
2、fiter
package com.um.core.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 javax.servlet.http.HttpSession;
import com.um.core.controller.BaseController;
/**
* 登录验证过滤器
*/
public class LoginFilter extends BaseController implements Filter {
/**
* 初始化
*/
public void init(FilterConfig fc) throws ServletException {
// FileUtil.createDir("d:/FH/topic/");
}
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
String[] notFilter = new String[] { "userLogin","js","xml","css","demo","img","images","fonts","common","gateway","payCallback","toOrderPage","show_order"};//过滤字段、路径。。。。。。
String urlPath = request.getServletPath();
Boolean flg = false;
for (String url : notFilter) {
if ((urlPath.contains(url))) {
flg = true;
}
}
if(flg){
chain.doFilter(req, res);
}else{
HttpSession session = request.getSession();
String UID = (String) session.getAttribute("UID"); //登录成功将登录ID放入session中，这里将session取出对比
if (null == UID||"".equals(UID)) {
logger.warn("用户登录超时或未登录，请重新登录！");
java.io.PrintWriter out = response.getWriter();
out.println("");
out.println("");
out.println("");
return;
}else {
chain.doFilter(req, res);
}
}
}
}