php生成uuid 工具方法

     /**     * 生成uuid     * @copyright [chenghuan]     * @license   [license]     * @version   [version]     * @return    [string]      [uuid] 长度36     */    function guid(){        $uuid = '';        if (function_exists('com_create_guid')){            return com_create_guid();        }else{            mt_srand((double)microtime()*10000);//optional for php 4.2.0 and up.            $charid = strtoupper(md5(uniqid(rand(), true)));            $hyphen = chr(45);// "-"            //$uuid = //chr(123)// "{"            $uuid .= substr($charid, 0, 8).$hyphen            .substr($charid, 8, 4).$hyphen            .substr($charid,12, 4).$hyphen            .substr($charid,16, 4).$hyphen            .substr($charid,20,12);            //.chr(125);// "}"            return $uuid;        }    }