Springboot : How to use WebClient instead of RestTemplate for Performing Non blocking and Asynchronous calls

Question

I have a springboot project which uses Springboot Resttemplate. We have moved to springboot 2.0.1 from 1.5.3 and we are trying to make the rest calls from it asynchronous by us

Answer 1

The first step is to build WebClient object with the baseUrl;

WebClient webClient = WebClient.builder()
    .baseUrl("http://localhost:8080/api") //baseUrl
    .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
    .build();

Then choose the method and append the path along with the request variables or body payload.

ResponseSpec responseSpec = webClient
    .get()
    .uri(uriBuilder -> uriBuilder.path("/findById") //additional path
        .queryParam("id", id).build())
    .retrieve()
    .onStatus(HttpStatus::is4xxClientError, response -> Mono.error(new CustomRuntimeException("Error")));

Wait for the response with block() function of bodyToMono. If you want response as String, you can convert it using google's gson library.

Object response = responseSpec.bodyToMono(Object.class).block();
Gson gson = new Gson();
String str = gson.toJson(response);

If you don't want to need to know the status of the api call, you can do like following.

webClient
    .post()
    .uri(uri -> uri.path("/save").build())
    .body( BodyInserters.fromObject(payload) )
    .exchange().subscribe();