ResponseEntity

See equivalent in the Reactive stack

ResponseEntity is like @ResponseBody but with status and headers. For example:

  • Java

  • Kotlin

@GetMapping("/something")
public ResponseEntity<String> handle() {
	String body = ... ;
	String etag = ... ;
	return ResponseEntity.ok().eTag(etag).body(body);
}
@GetMapping("/something")
fun handle(): ResponseEntity<String> {
	val body = ...
	val etag = ...
	return ResponseEntity.ok().eTag(etag).build(body)
}

Spring MVC supports using a single value reactive type to produce the ResponseEntity asynchronously, and/or single and multi-value reactive types for the body. This allows the following types of async responses:

  • ResponseEntity<Mono<T>> or ResponseEntity<Flux<T>> make the response status and headers known immediately while the body is provided asynchronously at a later point. Use Mono if the body consists of 0..1 values or Flux if it can produce multiple values.

  • Mono<ResponseEntity<T>> provides all three — response status, headers, and body, asynchronously at a later point. This allows the response status and headers to vary depending on the outcome of asynchronous request handling.