1、源地址列表文件路径
ubuntu系统的源列表配置文件的路径是：/etc/apt/ sources.list
为了在替换前留个备份，可以执行命令做个备份：
cp /etc/apt/sources.list /etc/apt/sources.list-bak
2、源地址列表文件的替换
不同的版本，sources.list里的url是不同的，主要是版本好不一样，例如ubuntu14.04的代号是trusty ，而ubuntu16.04是 xenial。
具体查看方法是执行命令：lsb_release -a 回车
返回的Codename就是版本代号
如图：
2.1 、ubuntu14.04版本
将/etc/apt/ sources.list的内容替换为：
debhttp://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
debhttp://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
debhttp://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
debhttp://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
debhttp://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe
替换后执行命令： sudo apt-get update
2.2、ubuntu16.04版本
将/etc/apt/ sources.list的内容替换为：
deb http://mirrors.aliyun.com/ubuntu/ xenial main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main multiverse restricted universe
debhttp://mirrors.aliyun.com/ubuntu/ xenial-security main multiverse restricted universe
debhttp://mirrors.aliyun.com/ubuntu/ xenial-updates main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ xenial main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ xenial-backports main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ xenial-proposed main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ xenial-security main multiverse restricted universe
deb-srchttp://mirrors.aliyun.com/ubuntu/ xenial-updates main multiverse restricted universe
替换后执行命令： sudo apt-get update