我是WordPress开发的新手。目前，我正在尝试制作一个小部件来嵌入youtube上的视频。我的计划是管理员或作者只需提供视频id，视频将在小部件区域。

我的代码如下：

index.php

<?php

/*
Plugin Name: Youtube
Plugin URI: imonislam.com
Author: smartrahat
Author URI: imonislam.com
Description: This plugin will embed youtube video on sidebar or any widget location you want.
Version: 1.0

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the license or
(at your option) any later version.

This program is distributes in hope that it will be useful, but without
any warranty; without even the implied warranty of MERCHANTABILITY or
FITNESS for a PARTICULAR PERSON. See the GNU General Public License
for more details.

You should have receive a copy of GNU General Public License,
if not, see http://www.gnu.com/licenses/
*/

require_once \'youtube.php\';

function register_youtube_widget(){
    register_widget(\'youtube\');
}

add_action(\'widgets_init\',\'register_youtube_widget\');

youtube.php

<?php

class youtube extends WP_Widget{

    public function __construct()
    {
        parent::WP_Widget(
            \'youtube\',
            __(\'Youtube\'),
            [
                \'description\' => \'paste your video id you want to embed\',
                \'class\' => \'youtube-widget\'
            ]
        );
    }

    public function form($instance)
    {
        $default = [
            \'title\' => __(\'\'),
            \'code\' => __(\'\')
        ];

        $instance = wp_parse_args((array)$instance,$default);

        echo "\\r\\n";
        echo \'<p>\';
        echo \'<label for="\'.$this->get_field_id(\'title\').\'">\'.__(\'Title\').\':</label>\';
        echo \'<input type="text" class="widefat" id="\'.$this->get_field_id(\'title\').\'" value="\'.esc_attr($instance[\'title\']).\'">\';
        echo \'</p>\';
        echo \'<p>\';
        echo \'<label for="\'.$this->get_field_id(\'code\').\'">\'.__(\'Code\').\':</label>\';
        echo \'<input type="text" class="widefat" id="\'.$this->get_field_id(\'code\').\'" value="\'.esc_attr($instance[\'code\']).\'">\';
        echo \'</p>\';
    }

    public function update($new_instance, $old_instance)
    {
        $instance = $old_instance;
        $instance[\'title\'] = strip_tags($new_instance[\'title\']);
        $instance[\'code\'] = $new_instance[\'code\'];

        return $instance;
    }

    public function widget($args, $instance)
    {
        extract($args,EXTR_SKIP);
        echo $before_widget;
        echo \'<iframe width="560" height="315" src="https://www.youtube.com/embed/\';
        echo $instance[\'code\'];
        echo \'" frameborder="0" allowfullscreen></iframe>\';
        echo $after_widget;
    }

}

视频播放器显示正确。但在widget中提供视频id后，视频不会播放。上面说，

发生错误。请稍后再试。

  $url = \'http://www.youtube.com/watch?v=fHBFvlQ3JGY\';
    preg_match(
            \'/[\\\\?\\\\&]v=([^\\\\?\\\\&]+)/\',
            $url,
            $matches
        );
    $id = $matches[1];

    $width = \'640\';
    $height = \'385\';
    echo \'<object width="\' . $width . \'" height="\' . $height . \'"><param name="movie" value="http://www.youtube.com/v/\' . $id . \'&amp;hl=en_US&amp;fs=1?rel=0"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/\' . $id . \'&amp;hl=en_US&amp;fs=1?rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="\' . $width . \'" height="\' . $height . \'"></embed></object>\';