stream流拼接树形结构

package cn.e4j.modular.iqs.utils;

import cn.e4j.core.dto.impl.Dto;
import cn.e4j.modular.iqs.entity.FrsadT;
import cn.e4j.modular.iqs.entity.TreeNode;
import cn.e4j.modular.iqs.service.impl.Frs04ServiceImpl;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.List;

@Component
public class BuildTreeUtil {

    @Resource
    private Frs04ServiceImpl frs04Service;

    public List<TreeNode> getFRSADTTreeList(Dto inDto) {
        List<FrsadT> parentId = frs04Service.getParentId(inDto);
        List<TreeNode> nodes = new ArrayList<>();
        List<FrsadT> list = frs04Service.getList();
        list.forEach(item -> {
            TreeNode treeNode = new TreeNode(item.getAD001(), item.getAD002(), item.getAD004(), item.getAD004());
            nodes.add(treeNode);
        });
        if (parentId != null) {
            return buildTree(nodes, parentId.get(0).getParent_code());
        }
        return null;
    }

    public static List<TreeNode> buildTree(List<TreeNode> treeNodes, String parentId) {
        List<TreeNode> treeList = new ArrayList<>();

        treeNodes.stream()
                .filter(node -> parentId.equals(node.getParentId()))
                .peek(treeList::add)
                .forEach(root -> addChildren(root, treeNodes));

        return treeList;
    }

    private static void addChildren(TreeNode treeNode, List<TreeNode> treeNodes) {
        treeNodes.stream()
                .filter(node -> treeNode.getId().equals(node.getParentId()))
                .peek(treeNode.getChildren()::add)
                .forEach(child -> addChildren(child, treeNodes));
    }
}