get_blog_id_from_url( string $domain, string $path = ‘/’ )

从博客的URL获取其数字ID。
Get a blog’s numeric ID from its URL.

目录锚点：#说明#返回#源码#笔记

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说明（Description）

在子目录安装中example.com/blog1网站/，$domain将是根目录’example.com网站’和$path子目录’/blog1/’。有像blog1这样的子域。example.com网站，$domain是’blog1。example.com网站’和$path是’/’。

返回（Return）

（int）如果没有找到blog，则为0，否则为匹配blog的ID

源码（Source）

/**
 * Get a blog's numeric ID from its URL.
 *
 * On a subdirectory installation like example.com/blog1/,
 * $domain will be the root 'example.com' and $path the
 * subdirectory '/blog1/'. With subdomains like blog1.example.com,
 * $domain is 'blog1.example.com' and $path is '/'.
 *
 * @since MU 2.6.5
 *
 * @global wpdb $wpdb
 *
 * @param string $domain
 * @param string $path   Optional. Not required for subdomain installations.
 * @return int 0 if no blog found, otherwise the ID of the matching blog
 */
function get_blog_id_from_url( $domain, $path = '/' ) {
	global $wpdb;

	$domain = strtolower( $domain );
	$path = strtolower( $path );
	$id = wp_cache_get( md5( $domain . $path ), 'blog-id-cache' );

	if ( $id == -1 ) // blog does not exist
		return 0;
	elseif ( $id )
		return (int) $id;

	$id = $wpdb->get_var( $wpdb->prepare( "SELECT blog_id FROM $wpdb->blogs WHERE domain = %s and path = %s /* get_blog_id_from_url */", $domain, $path ) );

	if ( ! $id ) {
		wp_cache_set( md5( $domain . $path ), -1, 'blog-id-cache' );
		return 0;
	}

	wp_cache_set( md5( $domain . $path ), $id, 'blog-id-cache' );

	return $id;
}

// Admin functions

笔记（Notes）

例子