//重写tree的loader
$.extend($.fn.tree.defaults, {
    loader : function (param, success, error) {
        var opts = $(this).tree("options");
        if (!opts.url) {
            return false;
        }
        if(opts.queryParams){
            param = $.extend({},opts.queryParams,param);
        }
        $.ajax({
            type : opts.method,
            url : opts.url,
            data : param,
            dataType : "json",
            success : function (data) {
                success(data);
            },
            error : function () {
                error.apply(this, arguments);
            }
        });
    },
    queryParams:{}
});
//设置参数
$.extend($.fn.tree.methods, {
    setQueryParams : function (jq, params) {
        return jq.each(function () {
            $(this).tree("options").queryParams = params;
        });
    }
});

$("#tree").tree({
    url:‘tree.do‘
    queryParams:{pid:1}
});

$("#tree").tree("setQueryParams",{pid:1});