var request;
function create_xml_http_request(){
	var arg;
	try{
		arg = new XMLHttpRequest();
	}catch(trymicrosoft){
    	try{
			arg = new ActiveXObject("Msxml2.XMLHTTP");
    	}catch(othermicrosoft){
			try{
				arg = new ActiveXObject("Microsoft.XMLHTTP");
			}catch(failed){
				arg = false;
			}
		}
	}
	if(!arg){
		alert("您的浏览器或浏览器设置不支持创建ajax对象!");
	}
	return arg;
}

function doit(uri, params) {
	request = create_xml_http_request();
	request.open("GET", uri, true);
	request.onreadystatechange = new Function("onOkDo('"+params+"')");
    request.send(null);
}
//uri => 需要远程调用的uri路径; cfn => 回调函数名称; cfp => 回调函数参数
function remoteCall(uri, cf) {
	request = create_xml_http_request();
	request.open("GET", uri, true);
	request.onreadystatechange = new Function(cf);
    request.send(null);
}
function postCall(uri, cf ,params){
	request = create_xml_http_request();
	request.open("POST",uri,true);
	request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
	request.onreadystatechange = new Function(cf);
	request.send(params);

}