直接在sources.list文件里边改
deb http://mirrors.aliyun.com/debian/ stretch main non-free contrib
deb http://mirrors.aliyun.com/debian/ stretch-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ stretch-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch-backports main non-free contrib
deb http://mirrors.aliyun.com/debian-security/ stretch/updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian-security/ stretch/updates main non-free contrib
参考文章