Yum安装中出现错误mirrorlist.txt的解决方法

发现问题

今天在使用Yum install命令安装软件的时候一直提示一个错误，错误提示如下面：

# yum install mysql
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
 Eg. /
removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/$releasever/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base