由于博客使用的是LayUI框架，在使用二级导航时，发现wordpress的wp_nav_menu()输出与LayUI自带的导航样式不搭配，因此只能稍微改造了一下wp_nav_menu()的输出方式。

重写wp_nav_menu() Walker参数

functions.php 写入

#-----------------------------------------------------------------#
# 修改wp_nav_menu的li标签
#-----------------------------------------------------------------#
class new_walker extends Walker_Nav_Menu{
	//修改一级ul标签样式
	function start_lvl( &$output, $depth = 0, $args = array() ){
		if( $depth == 0 ){
			$output .= \'<ul class=\"layui-nav-child\">\';
		}else{
			$output .= \'<ul class=\"layui-nav-child\">\';
		}
	}
	function end_lvl( &$output, $depth = 0, $args = array() ){
		if( $depth == 0 ){
			$output .= \"</ul>\";
		}else{
			$output .= \'</ul>\';
		}
	}
	function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
		if ( isset( $args->item_spacing ) && \'discard\' === $args->item_spacing ) {
		$t = \'\';
		$n = \'\';
		} else {
		$t = \"\\t\";
		$n = \"\\n\";
		}
		$indent = ( $depth ) ? str_repeat( $t, $depth ) : \'\';

		$classes   = empty( $item->classes ) ? array() : (array) $item->classes;
		$classes[] = \'menu-item-\' . $item->ID;

		$args = apply_filters( \'nav_menu_item_args\', $args, $item, $depth );

		$class_names = join( \' \', apply_filters( \'nav_menu_css_class\', array_filter( $classes ), $item, $args, $depth ) );
		if( $depth == 0 ){
			$class_names .= \' layui-nav-item\'; //增加Layui样式
		}
		if ( in_array( \'current-menu-item\', $classes ) ){
			$class_names .= \' layui-this\'; //增加当前样式
		}
		$class_names = $class_names ? \' class=\"\' . esc_attr( $class_names ) . \'\"\' : \'\';

		$id = apply_filters( \'nav_menu_item_id\', \'menu-item-\' . $item->ID, $item, $args, $depth );
		$id = $id ? \' id=\"\' . esc_attr( $id ) . \'\"\' : \'\';

		$output .= $indent . \'<li\' . $id . $class_names . \'>\';

		$atts           = array();
		$atts[\'title\']  = ! empty( $item->attr_title ) ? $item->attr_title : \'\';
		$atts[\'target\'] = ! empty( $item->target ) ? $item->target : \'\';
		if ( \'_blank\' === $item->target && empty( $item->xfn ) ) {
		$atts[\'rel\'] = \'noopener noreferrer\';
		} else {
		$atts[\'rel\'] = $item->xfn;
		}
		$atts[\'href\']         = ! empty( $item->url ) ? $item->url : \'\';
		$atts[\'aria-current\'] = $item->current ? \'page\' : \'\';

		$atts = apply_filters( \'nav_menu_link_attributes\', $atts, $item, $args, $depth );

		$attributes = \'\';
		foreach ( $atts as $attr => $value ) {
		if ( ! empty( $value ) ) {
			$value       = ( \'href\' === $attr ) ? esc_url( $value ) : esc_attr( $value );
			$attributes .= \' \' . $attr . \'=\"\' . $value . \'\"\';
		}
		}

		$title = apply_filters( \'the_title\', $item->title, $item->ID );

		$title = apply_filters( \'nav_menu_item_title\', $title, $item, $args, $depth );

		$item_output  = $args->before;
		$item_output .= \'<a\' . $attributes . \'>\';
		$item_output .= $args->link_before . $title . $args->link_after;
		$item_output .= \'</a>\';
		$item_output .= $args->after;

		$output .= apply_filters( \'walker_nav_menu_start_el\', $item_output, $item, $depth, $args );
	}
}

前端调用wp_nav_menu()

<?php
  wp_nav_menu( array( 
    \'theme_location\' => \'\', //导航别名
    \'menu_class\' => \'layui-nav\', //引用layui-nav样式
    \'walker\' => new new_walker(), //引用刚才的重构
  ));
?>

这样就可以愉快的使用wordpress的菜单功能了。