菜单递归

/**
 * @ClassName: FunctionService
 * @Description: 功能菜单
 * @author: yaozhenhua
 * @date: 2018/12/26 12:29
 */
@Service
public class MenuService {
    
    @Resource
    MenuDao menuDao;
    
    /**
     *查询可用且上线的菜单
     *
     * @param
     * @author: yaozhenhua  2019/3/27 17:24
     */
    public List listMenu() throws InstantiationException, IllegalAccessException, AobpException {
        //结果处理容器
        List menuVOS = new ArrayList<>();
        //查询一级菜单
        List menuBOS = menuDao.listParentMenu();
        if(!EmptyUtils.isEmpty(menuBOS)){
            //一级菜单排序
            Collections.sort(menuBOS, new Comparator() {
                @Override
                public int compare(MenuBO o1, MenuBO o2) {
                    int ret = 0;
                    ret = o1.getParentSequence().compareTo(o2.getParentSequence());
                    return ret;
                }
            });
                
            menuVOS = BeanCopyUtils.copyList(menuBOS,MenuVO.class);
          
            for(int i=0; i                MenuBO menuBO = menuBOS.get(i);
                MenuVO menuVO = menuVOS.get(i);
                //查询子菜单并排序
                List subMenuVOS = listSubMenu(menuBO.getId(),1);
                menuVO.setSubs(subMenuVOS);
                }
            }
        
        return menuVOS;
    }
    
    /**
     *根据父id查询子菜单
     *
     * @param parentId
     * @author: yaozhenhua  2019/3/27 17:24
     */
    public List listSubMenu(Long parentId, int alarm) throws InstantiationException, IllegalAccessException, AobpException {
        　//计数器 递归20次抛出异常，菜单层级最大没有超过20层的。
　　　　　if(alarm>20){
            throw new AobpException(ExceptionConstant.INTERNAL_ERR,"递归次数超过20次异常");
        }
        //查询出此父菜单下的子菜单
        List  menuBOS= menuDao.listMenuByParentId(parentId);
        //结果容器
        List menuVOS = new ArrayList<>();
        //查看子菜单是不是还有下一级菜单（判定条件  用id作为父id去查 ）
        if (!EmptyUtils.isEmpty(menuBOS)){
            Collections.sort(menuBOS, new Comparator() {
                @Override
                public int compare(MenuBO o1, MenuBO o2) {
                    int ret = 0;
                    ret = o1.getChildSequence().compareTo(o2.getChildSequence());
                    return ret;
                }
            });
    
            menuVOS = BeanCopyUtils.copyList(menuBOS,MenuVO.class);
    
            for (int i = 0; i < menuBOS.size(); i++) {
                MenuBO menuBO = menuBOS.get(i);
                MenuVO menuVO = menuVOS.get(i);
                List nextMenuVOS = listSubMenu(menuBO.getId(),alarm+1);
                if(!EmptyUtils.isEmpty(nextMenuVOS)){
    
                    menuVO.setSubs(nextMenuVOS);
                }
            }
           
            
        }
        return menuVOS;
    }
}


另一种方式：

/**
 * @ClassName: MenuService
 * @author: yaozhenhua
 * @date: 2019/3/27 15:59
 */
public class MenuService {
    
    @Transactional(readOnly = true)
    public List selectDocMenuList() {
        // 查询全部文档
        List rootMenuList = docDao.selectListExpUnable();
        // 最终的菜单
        List docList = new ArrayList();
        // 没有父ID的文档, 作为一级菜单
        for (Menu rootMenu : rootMenuList) {
            if (rootMenu.getDocPid() == null) {
                docList.add(rootMenu);
            }
        }
        
        // 为一级菜单添加子菜单
        for (Menu menu : docList) {
            menu.setChildList(getChild(menu.getDocId(), rootMenuList));
        }
        if (docList != null && docList.size() > 0) {
            // 为list排序
            this.mySort(docList, "docOrder", null);
        }
        
        return docList;
    }
    

    private List getChild(String docId, List rootMenu) {
        if (StringUtils.isBlank(docId)) {
            throw new BusinessException("文档id不能为空");
        }
        // 子菜单
        List childList = new ArrayList<>();
        for (Menu menu : rootMenu) {
            // 遍历所有节点，将父菜单id与传过来的type比较
            if (menu.getDocPid() != null) {
                if (menu.getDocPid().equals(docId)) {
                    childList.add(menu);
                }
            }
        }
        // 把子菜单的子菜单再循环一遍
        for (Menu menu : childList) {// 没有内容的子菜单还有子菜单
            try {
                if (menu.getDocContentHref() != null) {
                    menu.setDocContent(new String(menu.getDocContentHref(), "UTF-8"));
                }
                if (StringUtils.isBlank(menu.getDocContent())) {
                    // 递归
                    menu.setChildList(getChild(menu.getDocId(), rootMenu));
                }
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        } // 递归退出条件
        if (childList != null && childList.size() > 0) {
            this.mySort(childList, "docOrder", null);
        } else {
            return null;
        }
        
        return childList;
    }
}

菜单一般需要排序，我们根据Menu的order字段进行排序：

生成树的方法：

获取子菜单：