var sessreq = createSessionXMLHttpRequest();
var isLogin = 1;
function createSessionXMLHttpRequest() {
  var xmlhttpreq = false;
  if (window.XMLHttpRequest) {
    xmlhttpreq = new XMLHttpRequest();
  }
  else if (window.ActiveXObject) {    
    try {
      xmlhttpreq = new ActiveXObject("Msxml2.XMLHTTP");
    } 
	catch (e1) {
      try {
        xmlhttpreq = new ActiveXObject("Microsoft.XMLHTTP");

      } 
	  catch (e2) {
	          
      }
    }
  }
  return xmlhttpreq;
}
function sendSessionRequest() {
	sessreq.open("GET","/sessionServiceAction.do",false);
	sessreq.onreadystatechange = disposeSessionResponse;
	sessreq.send(null);
}
function disposeSessionResponse() {
    if (sessreq.readyState == 4) {
       if (sessreq.status == 200) {
	     	 if (sessreq.responseText == "00") isLogin = 0;
			 else isLogin = 1;
	   }
	   else {
	       alert("请求数据处理异常!");
	   }
    }
}
function checkIsLogin() {
    sendSessionRequest();
	if (isLogin == 0) return false;
	return true;
}