php 生成token----uuid

/**
 * 获取全球唯一标识
 * @return string
 */
public static function uuid()
{
    return sprintf(
        '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
        mt_rand(0, 0xffff),
        mt_rand(0, 0xffff),
        mt_rand(0, 0xffff),
        mt_rand(0, 0x0fff) | 0x4000,
        mt_rand(0, 0x3fff) | 0x8000,
        mt_rand(0, 0xffff),
        mt_rand(0, 0xffff),
        mt_rand(0, 0xffff)
    );
}