var bbstree_request = false;
var bbstree_div = "bbstree";
function send_bbstreerequest(url) {//初始化、指定处理函数、发送请求的函数
	bbstree_request = false;
	//开始初始化XMLHttpRequest对象
	if(window.XMLHttpRequest) { //Mozilla 浏览器
		bbstree_request = new XMLHttpRequest();
		if (bbstree_request.overrideMimeType) {//设置MiME类别
			bbstree_request.overrideMimeType("text/xml");
		}
	}
	else if (window.ActiveXObject) { // IE浏览器
		try {
			bbstree_request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				bbstree_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		}
	}
	if (!bbstree_request) { // 异常，创建对象实例失败
		window.alert("不能创建XMLHttpRequest对象实例.");
		return false;
	}
	bbstree_request.onreadystatechange = bbstreeinRequest;
	// 确定发送请求的方式和URL以及是否同步执行下段代码
	bbstree_request.open("GET", url, true);
	bbstree_request.send(null);
}
function loadbbstree(divname){	
	if(divname == null || divname=="")
		bbstree_div = "bbstree";
	else
		bbstree_div = divname;
	if(document.getElementById(bbstree_div).innerHTML == "")
	{
		document.getElementById(bbstree_div).innerHTML = "正在读取论坛目录……";
		send_bbstreerequest("/bbs/loadbbstree.asp");
	}
}
// 处理返回信息的函数
function bbstreeinRequest(){
	if (bbstree_request.readyState == 4) { // 判断对象状态
		if (bbstree_request.status == 200) { // 信息已经成功返回，开始处理信息
			document.getElementById(bbstree_div).innerHTML = bbstree_request.responseText;
		} else { //页面不正常
			alert("您所请求的页面有异常。");
		}
	}
}