Client-Side host load-balance

[PiemonJ]

• Feature Request. i have found my company use client-side ip load-balance,the http domain is a special service identifier，for example:global-user-credit，then have a common method to get ip list from register center,then perform client-side load balancing。but this special service identifier cannot be recognized by retrofit‘s HttpUrl class.so i have requirement,the OkHttpClient.Builder to provider a new method ,for example:baseUrlFactory，allows us to dynamically set base IP.

[JakeWharton]

Our general policy for this has been to use an OkHttp interceptor to rewrite the Request object to target the desired host. You can use a global host at the Retrofit layer or even just use a dummy domain like example.com to ensure the interceptor is required to rewrite the URL.

In the future, we may consider a factory for base URLs which is invoked each time a request is created.