更换Ubuntu更新源

第一种：(通过命令行进行更改)

# 先备份原有软件源
sudo cp /etc/apt/sourcre.list /etc/apt/sourcre.list.bak
# 打开配置文件
vim /etc/apt/sourcre.list
# 覆盖原有的软件源 复制下面内容 为Ubuntu16.04
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
# 预发布软件源，不建议启用
# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
# 命令更新源
sudo apt-get update && sudo apt-get upgrade

第二种：(Ubuntu图形界面设置)

• 点击system settings
• 点击software & updates
• 在Ubuntu Software栏中，找到Download from下拉选项，选择Other，在里面找到China，这个国家，里面的源都可使用
• 最后先点击Select Best Server，再点击Choose Server，之后再终端窗口使用sudo apt-get update进行验证就可