Java List 树形结构数据构造

public List select() {

    // 查询所有分类
    List classifyList = mdClassifyMapper.select(null);

    // 获取父节点分类
    List resultList = classifyList.stream().filter(r -> r.getParentId() == 0).collect(Collectors.toList());

    resultList.forEach(r -> {
        handleClassifyChild(r, classifyList);
    });

    return resultList;
}

/**
 * 递归处理分类父子数据
 */
private void handleClassifyChild(MdClassifyVO classify, List classifyList) {
    // 查询子节点数据
    List childList = classifyList.stream().filter(f -> f.getParentId().equals(classify.getId())).collect(Collectors.toList());
    classify.setClassifyChildList(childList);

    // 递归调用查询子集
    classify.getClassifyChildList().stream().forEach(r -> {
        handleClassifyChild(r, classifyList);
    });
}