update 2022.04.23:
The stable version of Ubuntu 22.04 has been released on April 21, 2022. The download address of Ubuntu 22.04 stable version is: https://ubuntu.com/download/desktop
The stable version of Ubuntu 22.04 is scheduled to be released on April 21, 2022. Development is already underway and it will follow the following release schedule:
February 24, 2022: Feature Freeze
March 17, 2022: User Interface Freeze
March 31, 2022: Beta Release April 14, 2022
: Release Candidate
April 21, 2022: Final Stable Release
Linux 5.15 LTS is the default kernel of Ubuntu 22.04, GCC 11.2 is the default system compiler, and Mesa 22.0 provides open source graphics driver support. Canonical has been developing a new desktop installer for Ubuntu, but with the release of 22.04 LTS, the existing Ubiquity will still be used by default.
If you want to test it on a spare machine or virtual machine, you can download the Ubuntu 22.04 daily builds from Ubuntu's website.
Download Ubuntu 22.04 daily build (unstable) https://cdimage.ubuntu.com/daily-live/current/
There are many Ubuntu image sources in China, including Alibaba’s, NetEase’s, and many education network sources, such as : Tsinghua University, University of Science and Technology of China.
Here we take Tsinghua Source as an example to explain how to modify the default source in Ubuntu 22.04.
Edit the /etc/apt/sources.list file and add the following entries at the front of the file (please make a backup before proceeding):
# 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/ jammy main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
# 预发布软件源，不建议启用
# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
sudo apt-get update
sudo apt-get upgrade