Spring CORS
CORS (Cross-Origin Resource Sharing)
It’s a mechanism to let a web application running at one domain, protocol or port have permission to access resources from a server at a different one.
This is needed if you have, for example, a Frontend running on port :3000 (React) consuming a Backend API running on port :34831 (custom port for Spring). Unless CORS are set, FE will not be able to access BE resources.
In Spring
It’s possible to enable them for a single RestResource or globally for the whole application.
(This example has been done in Kotlin)
By RestResource
@RestController
@RequestMapping("courses")
@CrossOrigin("http://localhost:3000")
class CourseRestResource {
// dependencies and methods
}