java 实现递归 ，返回树结构

第一步：获取结果集

 
    @Override
    public Result getReltionList(String formId) {
        if(StringUtils.isBlank(formId)){
            return Result.error(ResponseMessage.PARAMERROR);
        }
        LambdaQueryWrapper wrapper = new LambdaQueryWrapper<>();
        wrapper.eq(FormReltionship::getDeleteIf,true);
        wrapper.eq(FormReltionship::getFormId,formId);
        List shipList = formReltionshipMapper.selectList(wrapper);
        // 以树型结构返回
        List treeList = getTree("0",shipList);
        return Result.success(treeList);
    }

工具类：

public class FormUtils {

    
    public static List getTree(String parentId,List shipList){
        List formReltionshipList = new ArrayList<>();
        // 获取父节点
        List mainNodeList = getMainNode(parentId,shipList);
        mainNodeList.stream().forEach(x->{
            // 根据父节点下的子节点
            x=childShipList(x,shipList);
            formReltionshipList.add(x);
        });
        return formReltionshipList;
    }

    
    public static FormReltionship childShipList(FormReltionship ship,List shipList){
        List childList = new ArrayList<>();
        shipList.stream().forEach(x->{
            // 通过parentId 进行比较
            if(ship.getId().equals(x.getParentId())){
                // 如果为子节点,则判断子节点下是否存在节点
                childList.add(childShipList(x,shipList));
            }
        });
        ship.setChildrenList(childList);
        return ship;
    }

    
    public static List getMainNode(String parentId,List shipList){
        List reltionshipList = new ArrayList<>();
        shipList.stream().forEach(x->{
            if(parentId.equals(x.getParentId())){
                reltionshipList.add(x);
            }
        });
        return reltionshipList;
    }
}