* 功能1: 部門列表生成樹
 * 功能2: 設定樹的每個節點高度

 程式碼 : 

public class TreeDemo {


    //測試
    public static void main(String[] args) {

        long t1 = System.currentTimeMillis();

        //模擬初始資料集合
        List<TreeNode> list = initData();

        //計算樹結構
        TreeNodeVo tree = getTree(list);

        
 
//設定每個節點高度
        getHeight(tree);

        System.out.println("List耗時:" + (System.currentTimeMillis() - t1));

        System.out.println(JSONObject.toJSON(tree));
    }



    /**
     * *****************求樹高,最底層預設是1***************
     *
     *                 ------- 11-------111
     *                 |
     *      ------1----|
     *      |          |-------12
     *      |
     *  0---|
     *      |-----2----|--------21
     *
     *  例如 節點 111 的高度是1,  11高度是2  , 1 高度是 3
     *
     * *****************求樹高,最底層預設是1***************
     
 
*/
    private static Integer getHeight(TreeNodeVo tree) {
        List<TreeNodeVo> children = tree.getChildren();
        if (CollectionUtils.isEmpty(children)) {
            return 1;
        }

        //最大的兒子高度
        Integer maxHightSon = 1;
        for (TreeNodeVo vo : children) {
            
 
int heightOfChildren = getHeight(vo);

            vo.setHeight(heightOfChildren);

            System.out.println("vo.getName :" + vo.getName());
            System.out.println("vo.getHeight :" + vo.getHeight());

            maxHightSon = Math.max(heightOfChildren, maxHightSon);
        }

        tree.setHeight(maxHightSon + 1);
        System.out.println("tree.getName :" + tree.getName());
        System.out.println("tree.getHeight :" + tree.getHeight());

        return maxHightSon + 1;
    }


    private static TreeNodeVo getTree(List<TreeNode> list) {
        int count = 0;
        // 2. 根節點
        TreeNodeVo root = new TreeNodeVo();
        root.setId(-1);
        root.setName("根節點");

        // 3. 子節點 待下掛佇列
        LinkedList<TreeNodeVo> tempQueue = new LinkedList<>();

        tempQueue.add(root);

        while (!tempQueue.isEmpty() && list.size() > 0) {

            TreeNodeVo currentNodeVo = tempQueue.poll();

            for (int i = list.size() - 1; i >= 0; i--) {
                count++;

                TreeNode item = list.get(i);
                if (item.getParentId() != null && currentNodeVo.getId().equals(item.getParentId())) {
                    TreeNodeVo child = convert(item);
                    currentNodeVo.getChildren().add(child);

                    tempQueue.add(child);
                    list.remove(item);
                }
            }
        }

        System.out.println("迴圈次數:" + count);
        return root;

    }


    //copy
    private static TreeNodeVo convert(TreeNode node) {
        TreeNodeVo nodeVo = new TreeNodeVo();
        nodeVo.setId(node.getId());
        nodeVo.setName(node.getName());
        nodeVo.setParentId(node.getParentId());
        return nodeVo;
    }


    //初始化資料
    private static List<TreeNode> initData() {
        TreeNode node1 = new TreeNode();
        node1.setId(1);
        node1.setName("水果");
        node1.setParentId(-1);
        TreeNode node2 = new TreeNode();
        node2.setId(2);
        node2.setName("蔬菜");
        node2.setParentId(-1);

        TreeNode node3 = new TreeNode();
        node3.setId(3);
        node3.setName("蘋果");
        node3.setParentId(1);
        TreeNode node4 = new TreeNode();
        node4.setId(4);
        node4.setName("梨子");
        node4.setParentId(1);

        TreeNode node5 = new TreeNode();
        node5.setId(5);
        node5.setName("生菜");
        node5.setParentId(2);

        TreeNode node18 = new TreeNode();
        node18.setId(18);
        node18.setName("生包菜");
        node18.setParentId(5);

        TreeNode node6 = new TreeNode();
        node6.setId(6);
        node6.setName("紅蘋果");
        node6.setParentId(3);

        TreeNode node7 = new TreeNode();
        node7.setId(7);
        node7.setName("青梨子");
        node7.setParentId(4);

        TreeNode node9 = new TreeNode();
        node9.setId(9);
        node9.setName("熟菜");
        node9.setParentId(2);

        TreeNode node19 = new TreeNode();
        node19.setId(19);
        node19.setName("熟包菜");
        node19.setParentId(9);

        TreeNode node13 = new TreeNode();
        node13.setId(13);
        node13.setName("肉類");
        node13.setParentId(-1);

        TreeNode node14 = new TreeNode();
        node14.setId(14);
        node14.setName("牛肉");
        node14.setParentId(13);

        TreeNode node15 = new TreeNode();
        node15.setId(15);
        node15.setName("雞肉");
        node15.setParentId(13);

        TreeNode node16 = new TreeNode();
        node16.setId(16);
        node16.setName("牛腿肉");
        node16.setParentId(14);

        TreeNode node17 = new TreeNode();
        node17.setId(17);
        node17.setName("雞翅");
        node17.setParentId(15);


        List<TreeNode> list = new LinkedList<>();
        list.add(node1);
        list.add(node2);
        list.add(node3);
        list.add(node4);
        list.add(node5);
        list.add(node6);
        list.add(node7);
        list.add(node9);
        list.add(node13);
        list.add(node14);
        list.add(node15);
       // list.add(node16);
        list.add(node17);
        list.add(node18);
        list.add(node19);

        //打亂順序
        Collections.shuffle(list);
        return list;
    }


    @Data
    private static class TreeNode {
        private Integer id;
        private String name;
        private Integer parentId;

    }

    @Data
    private static class TreeNodeVo extends TreeNode {

        private Integer height;

        private List<TreeNodeVo> children = new ArrayList<>();
    }

}