从上图开始，后续操作如下，红色为操作的命令

[root@localhost yum.repos.d]# yum makecache
已加载插件：fastestmirror
Determining fastest mirrors
https://mirrors.aliyun.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#35 - "SSL received a record that exceeded the maximum permissible length."
正在尝试其它镜像。

 One of the configured repositories failed (CentOS-7 - Base),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=base ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable base
        or
            subscription-manager repos --disable=base

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=base.skip_if_unavailable=true

failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.
https://mirrors.aliyun.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#35 - "SSL received a record that exceeded the maximum permissible length."

[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]# vi CentOS-Base.repo    # 将所有https改为http后保存
[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]# yum makecache
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
base                                                     | 3.6 kB     00:00
https://mirrors.aliyun.com/centos/7/sclo/x86_64/rh/repodata/repomd.xml: [Errno 14] curl#35 - "SSL received a record that exceeded the maximum permissible length."
正在尝试其它镜像。

……内容同上面12345，省略……

[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]#
[root@localhost yum.repos.d]# vi CentOS-SCLo-rh.repo    # 将所有https改为http保存
[root@localhost yum.repos.d]# vi CentOS-SCLo-sclo.repo    # 将所有https改为http保存
[root@localhost yum.repos.d]# yum clean all
已加载插件：fastestmirror
正在清理软件源： base centos-sclo-rh centos-sclo-sclo extras updates
[root@localhost yum.repos.d]# yum makecache
已加载插件：fastestmirror
Determining fastest mirrors
base                                                     | 3.6 kB     00:00
centos-sclo-rh                                      | 3.0 kB     00:00
centos-sclo-sclo                                   | 3.0 kB     00:00
extras                                                   | 2.9 kB     00:00
updates                                                | 2.9 kB     00:00
(1/16): base/7/x86_64/group_gz                             | 153 kB   00:01
……省略……
(16/16): updates/7/x86_64/primary_db                   |  27 MB   05:53
元数据缓存已建立
[root@localhost yum.repos.d]#yum install -y vim    # 我的yum成功使用并安装