How are Spring Data repositories implemented by Spring at runtime?
Spring automatically generated code for you based on your YAML config that defined a MethodInterceptor chain that intercept calls to the instance and computed SQL on the fly.
A JDK proxy instance is created, which backs the repository interface, and a MethodInterceptor intercepts calls to the instance and routes as required.
The Spring JDK proxy creates a separate runtime process that acts as an intermediary between the database and the Web server, and intercepts calls to the instance and handles requests.
Spring automatically generated code for you based on your XML config files that define a SpringMethodAutoGeneration factory that intercepts calls to the instance and creates dynamic method that computer SQL on the fly.