wellcms 2.0 页头调用导航和子菜单的方式，直接复制使用。

第一种下拉菜单：

<ul class="navbar-nav mr-auto">   <li class="nav-item home" fid="0" data-active="fid-0">      <a class="nav-link" href="<?php echo $conf['path'] ;?>"><i class="icon-home d-md-none"></i>&nbsp;<?php echo lang('index_page');?></a>   </li>   <!-- 遍历需要显示的导航 -->   <?php if ($forum_nav = category_tree(GLOBALS('forum_nav'))) { foreach($forum_nav as $_forum) { ?>   <!-- li 格式 重新定义或添加新 class -->   <li class="nav-item <?php if ($_forum['son']){echo 'dropdown';}?>" fid="<?php echo $_forum['fid'];?>" data-active="fid-<?php echo $_forum['fid'];?>">      <!-- a标签格式 重新定义或添加新 class -->      <a class="nav-link <?php if ($_forum['son']){echo 'dropdown-toggle';}?>" href="<?php echo $_forum['url'];?>" <?php if ($_forum['son']){echo 'id="Menu-'.$_forum['fid'].'" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"';}?> <?php if ($_forum['category'] == 3){echo 'target="_blank"';}?>>         <i class="icon-circle-o d-md-none"></i>&nbsp;<?php echo $_forum['name'];?>      </a>      <!--子菜单-->      <?php if (isset($_forum['sonlist'])){ ?>      <div class="dropdown-menu" aria-labelledby="Menu-<?php echo $_forum['fid'];?>">         <?php foreach($_forum['sonlist'] as $_son) { ?>         <!-- a标签格式 重新定义或添加新 class -->
         <a class="dropdown-item" href="<?php echo $_son['url'];?>" <?php if ($_son['category'] == 3){echo 'target="_blank"';}?>>            <i class="icon-circle-o d-md-none"></i>&nbsp;<?php echo $_son['name'];?>         </a>         <?php } ?>      </div>      <?php }?>   </li>   <?php }} ?></ul>
 /*
关闭click.bs.dropdown.data-api事件，使头部顶级菜单可点击，如鼠标点击无法弹出，请 css 追加
.navbar-nav > li:hover .dropdown-menu {display: block;}
span.dropdown:hover .dropdown-menu {display: block;}
*/

第二种：点击频道后进入频道页面后，显示的横向子导航。

（1）频道页面使用的代码：

<?php if ($forum_nav[$forum['fid']]['son']) { ?><div class="container">    <ul class="nav">        <?php $forum_nav = category_tree(GLOBALS('forum_nav')); foreach($forum_nav[$forum['fid']]['sonlist'] as $_forum) { ?>        <li class="nav-item" fid="<?php echo $_forum['fid'];?>" data-active="fid-<?php echo $_forum['fid'];?>">            <a class="nav-link" href="<?php echo $_forum['url'];?>">            <?php echo $_forum['name'];?>            </a>        </li>        <?php } ?>    </ul></div><?php } ?>

（2）子栏目页面使用的代码：

<?php if ($forum['fup']) { ?><div class="container">    <ul class="nav"><!--
如果没有设置导航显示
<?php $forum_nav = category_tree(GLOBALS('forum_nav')); foreach($forum_nav[$forum['fup']]['sonlist'] as $_forum) { ?>
替换成如下代码
<?php $_forumlist = category_tree(GLOBALS('forumlist')); foreach($_forumlist[$forum['fup']]['sonlist'] as $_forum) { ?>
-->    <?php $forum_nav = category_tree(GLOBALS('forum_nav')); foreach($forum_nav[$forum['fup']]['sonlist'] as $_forum) { ?>        <li class="nav-item" fid="<?php echo $_forum['fid'];?>" data-active="fid-<?php echo $_forum['fid'];?>">            <a class="nav-link" href="<?php echo $_forum['url'];?>">            <?php echo $_forum['name'];?>            </a>        </li>    <?php } ?>    </ul></div><?php } ?>