Workarounds for modifying environment variables in CentOS, resulting in command loss

I beginner Linux, when installing the JDK, modify environment variables resulting in a large number of command loss?

In fact, the command is still in the system, but due to the environment variable error, resulting in the modification of the command can not be found in the previous way, so the above problem occurs.

At this point we can invoke the command through the absolute path and change the environment variable back.

/bin/vi This is the absolute path of the VI editor

After that the problem can be solved by oneself.

Workarounds for modifying environment variables in CentOS, resulting in command loss