重启后，Apache的跨域配置没有生效？

1、配置Apache服务器后，本地测试，页面访问b.com域名是可以的。但是跨域的配置却没有生效。

2、相关的header模块、rewrite模块都打开了。httpd-2.3.33的Apache虚拟主机配置文件如下：

<VirtualHost *:80>

    ServerName b.com

    ErrorLog "logs/b.com-error.log"

    CustomLog "logs/b.com-access.log" common

ProxyPass /http://localhost:8080/

#把请求头的origin值返回到Access-Control-Allow-Origin字段

Header always set Access-Control-Allow-Origin "expr=%{req:origin}"

#把请求头的Access-Control-Request-Headers值返回到Access-Control-Allow-Headers字段

Header always set Access-Control-Allow-Headers "expr=%{req:Access-Control-Request-Headers}"

Header always set Access-Control-Allow-Methods "*"

Header always set Access-Control-Allow-Credentials "true"

Header always set Access-Control-Max-Age "3600"

#处理预检命令OPTIONS,直接返回204

RewriteEngine On

RewriteCond %{REQUEST_METHOD} OPTIONS

RewriteRule ^(.*)$ "/" [R=204,L]

</VirtualHost>