php获取uuid

$uuid = bin2hex(openssl_random_pseudo_bytes(16));

<?php
$str = "Shanghai";
echo "字符串：".$str."<br>";
echo "TRUE - 原始 20 字符二进制格式：".sha1($str, TRUE)."<br>";
echo "FALSE - 40 字符十六进制数：".sha1($str)."<br>";
?>