Can I Set the Domain Name of an API to My Own Domain Name?

Yes. The procedure is as follows:

1. Log in to the APIG console and bind a domain name by referring to section "Binding a Domain Name" in the API Gateway User Guide.
2. On the Domain Names tab page of the created API group, click Bind Independent Domain Name. For example, set xxxx.apig.x to test.com/user/get.