在wp-include/functions.php里添加函数,启用ssl来获得图片

function get_ssl_avatar($avatar) {
   $avatar = preg_replace('/.*\/avatar\/(.*)\?s=([\d]+)&.*/','<img src="https://secure.gravatar.com/avatar/$1?s=$2" class="avatar avatar-$2" height="$2" width="$2">',$avatar);
   return $avatar;
}
add_filter('get_avatar', 'get_ssl_avatar');