创建一个简单的短链服务类

整理一个简单的短链算法,整理到自己的代码库中:

<?php
/**
 * 短链服务
 * @author vb2005xu
 */
class Service_ShortUrlGenerator
{
	
	private static $table = 'short_url';
	
	private static $list = array();
	
    function __construct(array $config)
    {
        if ( empty($config['db']) )
        {
        	throw BaseError::invalid_parameters_error('key "db" not set');
        }        
        $this->_db = $config['db'];
    }
    
    /**
     * 获取指定用户创建的短链集合
     *
     * @param int $uid
     * @param int $skip
     * @param int $limit
     * 
     * @return array
     */
    function getAllByUid( $uid , $skip=0, $limit=10 )
    {
    	$rows = DataSource::instance($this->_db)->select(self::$table,array(
    					'uid' => $uid,
    				),'*',null,$skip,$limit);
    				
    	return $rows;
    }
    
    /**
     * 获取指定用户创建的短链总数
     *
     * @param int $uid
     * 
     * @return int
     */
    function getCountByUid( $uid )
    {
    	return DataSource::instance($this->_db)->count(self::$table,array(
    					'uid' => $uid,
    				));
    }
    
    /**
     * 通过短链标识 获取对应的 url
     *
     * @param string $identify
     * @param int 	 $uid
     * 
     * @return string
     */
    function decode( $identify , $uid )
    {
    	$uid = intval($uid);
    	if ( !empty($identify) && $uid > 0 ) 
    	{
    		$identify = trim($identify);
    		if ( strlen( $identify ) == 6 )
    		{
    			if ( !isset( self::$list[$id] ) )
    			{
    				$row = DataSource::instance($this->_db)->find_one(self::$table,array(
    					'uid' => $uid,
    					'identify' => $identify,
    				),'link');
    				
    				self::$list[$identify] = empty($row['link']) ? NULL : $row['link'];
    			}
    			
    			return self::$list[$identify];
    		}
    	}
    	return null;
    }
    
	/**
	 * 返回6位的短链标识
	 *
	 * @param string $url
	 * 
	 * @return string
	 */
	function encode( $url , $uid  )
	{
		$uid = intval($uid);
    	if ( !empty($url) && $uid > 0 ) 
    	{
    		$url = trim($url);
    		$identify = self::generate( $url );
    		
    		# 放在此处做下缓存
    		self::$list[$identify] = $url;
    		
    		# 因为 uid + identify 做了唯一键索引,故此处不进行数据存在校验
    		DataSource::instance($this->_db)->insert(self::$table,array(
    			'uid' => $uid,
    			'identify' => $identify,
    			'link' => $link,
    			'create_at' => APP_START_TIMESTAMP,
    		));
    		
    		return $identify;
    	}
		return null;
	}
	
	/**
	 * 返回6位的短链标识
	 *
	 * @param string $url
	 * 
	 * @return string
	 */
	static function identify( $url )
	{
		if ( empty($url) ) return FALSE;
		return self::code62( sprintf("%u", crc32($url)) );
	}

	private static function code62($x) {
		$show = '';
		while($x > 0) {
			$s = $x % 62;
			if ($s > 35) {
				$s = chr($s+61);
			} elseif ($s > 9 && $s <=35) {
				$s = chr($s + 55);
			}
			$show .= $s;
			$x = floor($x/62);
		}
		return $show;
	}
}