修改AppStream对应的配置文件

vim /etc/yum.repos.d/CentOS-AppStream.repo
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=AppStream&infra=$infra
baseurl=https://mirrors.aliyun.com/centos/8.1.1911/AppStream/x86_64/os/
修改BaseOS库
vim /etc/yum.repos.d/CentOS-Base.repo 
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=BaseOS&infra=$infra
baseurl=https://mirrors.aliyun.com/centos/8.1.1911/BaseOS/x86_64/os/
修改Extra库
vim /etc/yum.repos.d/CentOS-Extras.repo
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
baseurl=https://mirrors.aliyun.com/centos/8.1.1911/extras/x86_64/os/