...
WebClient at the other hand is based on the Spring Reactive framework which provides capability to non-blocking async calls thanks to it's event-driven architecture. Because of this WebClient uses less resources (threads, memory).
Affected classes
Apart from the *Spec files the RestTemplate is used only in 2 classes: NcmpConfiguration and DmiRestClient.
The first class configures the client while the second performs requests with RestClient.
These two classes have to be rewritten/refactored to use the WebClient.
Example configuration
| Code Block | ||||||||
|---|---|---|---|---|---|---|---|---|
| ||||||||
@Slf4j
@Configuration
@AllArgsConstructor
public class WebClientConfiguration {
public static final int TIMEOUT = 2000;
private final DmiConfiguration.SdncProperties sdncProperties;
@Bean
public WebClient webClient() {
final var httpClient = HttpClient.create()
.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, TIMEOUT) // millis
.doOnConnected(connection ->
connection
.addHandlerLast(new ReadTimeoutHandler(TIMEOUT, TimeUnit.MILLISECONDS)) // millis
.addHandlerLast(new WriteTimeoutHandler(TIMEOUT, TimeUnit.MILLISECONDS))); //millis
return WebClient.builder()
.baseUrl(sdncProperties.getBaseUrl())
.defaultHeaders(header -> header.set(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE))
.defaultHeaders(header -> header.setBasicAuth(sdncProperties.getAuthUsername(), sdncProperties.getAuthPassword()))
.clientConnector(new ReactorClientHttpConnector(httpClient))
.filter(logRequest())
.filter(logResponse())
.build();
}
private ExchangeFilterFunction logRequest() {
return (clientRequest, next) -> {
log.info("Request: {} {}", clientRequest.method(), clientRequest.url());
log.info("--- Http Headers: ---");
clientRequest.headers().forEach(this::logHeader);
log.info("--- Http Cookies: ---");
clientRequest.cookies().forEach(this::logHeader);
return next.exchange(clientRequest);
};
}
private ExchangeFilterFunction logResponse() {
return ExchangeFilterFunction.ofResponseProcessor(clientResponse -> {
log.info("Response: {}", clientResponse.statusCode());
clientResponse.headers().asHttpHeaders()
.forEach((name, values) -> values.forEach(value -> log.info("{}={}", name, value)));
return Mono.just(clientResponse);
});
}
private void logHeader(String name, List values) {
values.forEach(value -> log.info("{}={}", name, value));
}
} |
...
| Code Block | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||
String response = webClient
.get()
.uri(resourceUrl)
.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
.retrieve()
.onStatus(HttpStatus::is4xxClientError,
error -> Mono.error(new RuntimeException("API not found")))
.onStatus(HttpStatus::is5xxServerError,
error -> Mono.error(new RuntimeException("Server is not responding")))
.bodyToMono(String.class)
.block();
return ResponseEntity.ok(response); |
...
Async call example with
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subscription
| Code Block | ||||||||
|---|---|---|---|---|---|---|---|---|
| ||||||||
public Mono<String> httpOperationWithJsonData(final HttpMethod httpMethod,
final String resourceUrl,
final String jsonData,
final HttpHeaders httpHeaders) {
return webClient
.get()
.uri(resourceUrl)
.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
.retrieve()
.onStatus(HttpStatus::is4xxClientError,
error -> Mono.error(new RuntimeException("API not found")))
.onStatus(HttpStatus::is5xxServerError,
error -> Mono.error(new RuntimeException("Server is not responding")))
.bodyToMono(String.class);
} |
...