JXTree对象，读取外部xml文件数据，生成树的函数

        level = stack.pop();
    }

    //得到解释结果并返回
    this.getTree = function(){
        this.parseXML(DOMRoot);
        DOMRoot = null;//释放DOM对象
        return result.join("");
    }
    /*************静态属性***************/
    JXTree.curText = null;//当前文本的id

    /************静态方法***************/
    JXTree.changeState = function (id){//展开或者收缩节点内容
        var _body = document.getElementById(id + "_body");
        var _join = document.getElementById(id+"_join");
        var folder = document.getElementById(id+"_folder");
        (_body.style.display == "none") ? (
            _body.style.display = "block",
            _join.className = _join.className.replace("plus","minus"),
            folder.className = "folder_open"
        ) : (
            _body.style.display = "none",
            _join.className = _join.className.replace("minus","plus"),
            folder.className = "folder_close"
        )
    };//changeState
    JXTree.setFocus = function(id){
        if(JXTree.curText)
            with(document.getElementById(JXTree.curText).style){
                backgroundColor = "";
                color = "#000";
            }
            with(    document.getElementById(id).style){
                backgroundColor = "#003366";