var HTTP = {};
HTTP._factories = [
 function(){return new XMLHttpRequest();},
 function(){return new ActiveXObject("Msxml2.XMLHTTP");},
 function(){return new ActiveXObject("Microsoft.XMLHTTP");}
];

HTTP._factory=null;

HTTP.newRequest = function() {
 if(HTTP._factory != null) 
 	return HTTP._factory();
 for (var i=0;i<HTTP._factories.length;i++) {
  try{
   var factory=HTTP._factories[i];
   var request=factory();
   if(request!=null){
    HTTP._factory=factory;
    return request;
   }
  }
  catch(e){
   continue;
  }
 }
 
 HTTP._factory=function(){
  throw new Error("您的浏览器设置为不支持Ajax，请寻求帮助以解决问题！");
 }
 HTTP._factory();
}