1、可能原因：SELinux限制了Apache的端口设置
2、解决办法：

//安装semanage
yum provides /usr/sbin/semanage
yum -y install policycoreutils-python
//查看默认允许的端口
semanage port -l | grep -w http_port_t
// http_port_t  tcp 80, 81, 443, 488, 8008, 8009, 8443, 9000
//使用semanage添加apache侦听的端口
semanage port -a -t http_port_t -p tcp 8888
//启动apache
systemctl start httpd