如何使用 Spring WebClient 進行具有不同標頭設置的后續調用？

Question

我需要調用第三方 API，該 API 需要事先進行身份驗證調用才能獲取身份驗證令牌。 身份驗證 API 在 json 中，但后續調用在 XML 中。

我分別有：

webclient.post().uri("/auth").header(ACCEPT,JSON).retrieve()
      .bodyToMono(AuthToken.class);
webclient.post().uri("/api").header(ACCEPT,XML).header("AUTH",authToken).retrive().bodyToFlux();

我應該如何實現能夠訪問第二個 API 的方法？ 我試圖用token = firstCall.block()在方法內分配一個變量，但我有block() is not supported錯誤。

Answer 1

你只需要像這樣轉換原始通量：

webclient.post().uri("/auth")
    .header(ACCEPT,JSON)
    .retrieve()
    .bodyToMono(AuthToken.class)
    .flatMapMany(authToken -> webclient.post().uri("/api")
    .header(ACCEPT,XML)
    .header("AUTH",authToken).retrive().bodyToFlux();

更好的解決方案是使用 ExchangeFilterFunction 為您獲取令牌https://docs.spring.io/spring-framework/docs/current/spring-framework-reference/web-reactive.html#webflux-client-篩選

類似的東西（未測試可能有錯誤）：

WebClient authWebClient = WebClient.builder().build();
WebClient webClient = WebClient.builder()
        .filter(((request, next) -> authWebClient.post()
                .uri("/auth")
                .accept(MediaType.APPLICATION_JSON)
                .retrieve()
                .bodyToMono(AuthToken.class)
                .flatMap(authToken -> next.exchange(ClientRequest.from(request)
                        .headers(headers -> headers.add("AUTH", authToken))
                        .build()))
        ))
        .build();

webClient.post().uri("/api")
        .accept(MediaType.APPLICATION_XML)
        .retrieve()
        .bodyToFlux(MyData.class);

這是基本的，但您可以添加緩存以避免在令牌過期時再次請求或獲取...請注意，基本的 oauth2 存在內置 ExchangeFilterFunction ...

用彈簧配置包裹一切：

@Configuration
public class WebClientConfiguration {
    @Bean
    public WebClient authWebClient(final WebClient.Builder webClientBuilder) {
        return webClientBuilder.build();
    }

    @Bean
    public ExchangeFilterFunction authFilter(final WebClient authWebClient) {
        return (request, next) -> authWebClient.post()
                .uri("/auth")
                .accept(MediaType.APPLICATION_JSON)
                .retrieve()
                .bodyToMono(AuthToken.class)
                .flatMap(authToken -> next.exchange(ClientRequest.from(request)
                        .headers(headers -> headers.add("AUTH", authToken.toString()))
                        .build()));
    }

    @Bean
    public WebClient webClient(final WebClient.Builder webClientBuilder, final ExchangeFilterFunction authFilter) {
        return webClientBuilder
                .filter(authFilter)
                .build();
    }
}

或者，如果您想避免使用 lambda：

@Configuration
public class WebClientConfiguration {
@Bean
    public WebClient authWebClient(final WebClient.Builder webClientBuilder) {
        return webClientBuilder.build();
    }

    @Bean
    public WebClient webClient(final WebClient.Builder webClientBuilder, final AuthFilter authFilter) {
        return webClientBuilder
                .filter(authFilter)
                .build();
    }
    
    @Bean
    public AuthFilter authFilter(WebClient authWebClient) {
        return new AuthFilter(authWebClient);
    }
}

public class AuthFilter implements ExchangeFilterFunction {

    private final WebClient authWebClient;

    public AuthFilter(WebClient authWebClient) {
        this.authWebClient = authWebClient;
    }

    @Override
    public Mono<ClientResponse> filter(final ClientRequest request, final ExchangeFunction next) {
        return authWebClient.post()
                .uri("/auth")
                .accept(MediaType.APPLICATION_JSON)
                .retrieve()
                .bodyToMono(AuthToken.class)
                .flatMap(authToken -> next.exchange(ClientRequest.from(request)
                        .headers(headers -> headers.add("AUTH", authToken.toString()))
                        .build()));
    }

}