JAVA生成树形结构代码

数据库列
id
parentId
name

替换代码中的实体类

最后调用buildMenuTree(List cates)方法即可生成树形结构！

    /**
     * 判断是否有子节点
     */
    private boolean hasChild(List<FolderDto> list, FolderDto p) {
        return getChildList(list, p).size() > 0 ? true : false;
    }


    private void recursionFn(List<FolderDto> list, FolderDto p) {
        // 得到子节点列表
        List<FolderDto> childList = getChildList(list, p);
        p.setChildren(childList);
        for (FolderDto tChild : childList) {
            if (hasChild(list, tChild)) {
                recursionFn(list, tChild);
            }
        }
    }

    public List<FolderDto> buildMenuTree(List<FolderDto> cates) {
        List<FolderDto> returnList = new ArrayList<FolderDto>();
        List<String> tempList = new ArrayList<String>();
        for (FolderDto cate : cates) {
            tempList.add(cate.getId());
        }
        for (Iterator<FolderDto> iterator = cates.iterator(); iterator.hasNext();) {
            FolderDto cate = (FolderDto) iterator.next();
            // 如果是顶级节点, 遍历该父节点的所有子节点
            if (!tempList.contains(cate.getParenId())) {
                recursionFn(cates, cate);
                returnList.add(cate);
            }
        }
        if (returnList.isEmpty()) {
            returnList = cates;
        }
        return returnList;
    }


    private List<FolderDto> getChildList(List<FolderDto> list, FolderDto p) {
        List<FolderDto> tlist = new ArrayList<FolderDto>();
        Iterator<FolderDto> it = list.iterator();
        while (it.hasNext()) {
            FolderDto n = (FolderDto) it.next();
            if (n.getParenId().equals( p.getId())) {
                tlist.add(n);
            }
        }
        return tlist;
    }