ztree 展开一级节点

// 默认展开一级节点
var nodes = tree.getNodesByParam("level", 0);
for (var i = 0; i < nodes.length; i++) {
    tree.expandNode(nodes[i], true, false, false);
}

//ztree只显示到二级目录
var nodes2 = tree.getNodesByParam("level", 1);
for (var j = 0; j < nodes2.length; j++) {
    tree.removeChildNodes(nodes2[j]);
}