Jmeter- Interface environment variable

Premise: During the test, domain names and online test environment, test data interfaces are not the same.
Resulting in the need one interface to change, too much trouble; Here's a way to solve the problem
1, the test plan - add - user-defined variables

2, in the request interface, {variable names defined by the user} with $ to reference. You can directly reference the variable

3, the follow-up if the value of the variable changes, which only need to modify the test program - the value of user-defined variable on it