URL地址相对路径转绝对路径

URL相对路径转绝对路径

在做爬虫或者网页解析时，经常会从网页中提取到很多相对URL，在做进一步爬取之前，我们需要将这个地址转成完整的URL，其实URL和文件路径是相似的，看似很简单，实则有很多情况需要考虑，网上提供的很多方法都会有各种各样的问题，这里提供了一个相对靠谱的方法，代码如下。

echo PhpUri::doIt("https://www.google.com/", "foo");
//输出 https://www.google.com/foo

class PhpUri
{
public $scheme;
public $authority;
public $path;
public $query;
public $fragment;

/**
 * 调用这个方法进行转换
 *
 * @param $baseUrl
 * @param $relativeUrl
 * @return string
 */
public static function doIt($baseUrl, $relativeUrl)
 {
return self::parse($baseUrl)->join($relativeUrl);
    }

/**
 * PhpUri constructor.
 */
public function __construct($url)
 {
        preg_match_all( '/^(([^:\/?#]+):)?(\/\/([^\/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?$/',
$url, $matches);
$this->scheme = $matches[2][0];
$this->authority = $matches[4][0];
$this->path = $matches[5][0];
$this->query = $matches[7][0];
$this->fragment = $matches[9][0];
    }


public static function parse($url)
 {
$uri = new PhpUri($url);
if(empty($uri->path))
$uri->path = '/';

return $uri;
    }


public function join($relative)
 {
$uri = new PhpUri($relative);
switch (true)
        {
case !empty($uri->scheme):
break;
case !empty($uri->authority):
break;
case empty($uri->path):
$uri->path = $this->path;
if (empty($uri->query))
                {
$uri->query = $this->query;
                }
break;
case strpos($uri->path, '/')===0:
break;
default:
$base_path = $this->path;
if (strpos( $base_path, '/' ) === FALSE)
                {
$base_path = '';
                }
else
                {
$base_path = preg_replace('/\/[^\/]+$/', '/', $base_path);
                }
if (empty($base_path) && empty($this->authority))
                {
$base_path = '/';
                }
$uri->path = $base_path.$uri->path;
        }


if (empty($uri->scheme))
        {
$uri->scheme = $this->scheme;
if (empty($uri->authority ))
            {
$uri->authority = $this->authority;
            }
        }
return $uri->toStr();
    }



private function toStr()
 {
$ret = '';
if ( !empty( $this->scheme ) )
        {
$ret .= "{$this->scheme}:";
        }
if ( !empty( $this->authority ) )
        {
$ret .= "//{$this->authority}";
        }
$ret .= $this->normalizePath( $this->path );
if ( !empty( $this->query ) )
        {
$ret .= "?{$this->query}";
        }
if ( !empty( $this->fragment ) )
        {
$ret .= "#{$this->fragment}";
        }
return $ret;
    }



private function normalizePath( $path )
 {
if ( empty( $path ) )
        {
return '';
        }
$normalized_path = $path;
$normalized_path = preg_replace( '`//+`', '/', $normalized_path, -1, $c0 );
$normalized_path = preg_replace( '`^/\\.\\.?/`', '/', $normalized_path, -1, $c1 );
$normalized_path = preg_replace( '`/\\.(/|$)`', '/', $normalized_path, -1, $c2 );
/**
 * CHANGE:
 * @author Dominik Habichtsberg <[e-mail]>
 * @since 24 Mai 2015 10:05 Uhr
 * changed limit form -1 to 1, because climbing up the directory-tree failed
 */
$normalized_path = preg_replace( '`/[^/]*?/\\.\\.(/|$)`', '/', $normalized_path, 1, $c3 );
$num_matches     = $c0 + $c1 + $c2 + $c3;
return ( $num_matches > 0 ) ? $this->normalizePath( $normalized_path ) : $normalized_path;
    }
}

参考

• monkeysuffrage/phpuri