我正在学习创建一个元框来上传文件wp-content/uploads 通过以下代码创建文件夹：

//display image meta box
function display_image_box() {
    global $post;
    wp_nonce_field( plugin_basename( __FILE__ ), \'wp_custom_noncename\' );
    echo \'<input id="post_media" type="file" name="post_media" value="" size="25" />\';
}

//upload image 
function update_custom_meta_data( $id, $data_key, $is_file = false ) {
    if( $is_file && ! empty( $_FILES ) ) {
        $upload = wp_handle_upload( $_FILES[$data_key], array( \'test_form\' => false ) );
        if( isset( $upload[\'error\'] ) && \'0\' != $upload[\'error\'] ) {
            wp_die( \'There was an error uploading your file. \' );
        } else {
            update_post_meta( $id, $data_key, $upload );
        } 
    }  
}
//save image
function save_custom_meta_data( $id ) {
    if( ! wp_verify_nonce( $_POST[\'wp_custom_noncename\'], plugin_basename( __FILE__ ) ) ) {
        return;
    } 
    if( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE ) {
        return;
    } 
    update_custom_meta_data( $id, \'post_media\', true );
} 
add_action( \'save_post\', \'save_custom_meta_data\' );

//register script
function register_admin_scripts() {
    wp_register_script( \'custom_admin_script\', get_template_directory_uri() . \'/js/admin.js\' );
    wp_enqueue_script( \'custom_admin_script\' );
}
add_action( \'admin_enqueue_scripts\', \'register_admin_scripts\' );

这很有效，文件上传很好，但我无法显示它，因为我得到的数组如下所示：

[post_media] => Array
(
    [0] => a:3:{s:4:"file";s:81:"E:wampwwwtestchild/wp-content/themes/twentyeleven/uploads/2012/12/coffee_star.jpg";s:3:"url";s:60:"wp-content/themes/twentyeleven/image/2012/12/coffee_star.jpg";s:4:"type";s:10:"image/jpeg";}
)

如何在模板中显示图像
此外，如何保存URL（wp-content/themes/twentyeleven/image/2012/12/coffee_star.jpg ) 仅作为元数据？