有没有办法在使用SpringCloud OpenFeign时为每个Feign实例创建不同的客户端？

Question

我们可以在使用OpenFeign时指定Feign实例的客户端，如下所示：

        his.fooClient = Feign.builder()
                .client(clientA)
                .target(FooClient.class, "https://PROD-SVC");

        this.adminClient = Feign.builder()
                .client(clientB)
                .target(FooClient.class, "https://PROD-SVC");

但是，如果使用SpringCloud OpenFeign，似乎没有办法做到这一点，所有的Feign实例将共享一个客户端，因为我们无法根据文件名：https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/appendix.html为Feign实例配置客户端。

那么，如何在使用SpringCloud OpenFeign的同时实现这一目标呢？

Answer 1

您必须手动创建Feign实例，与使用OpenFeign的方式相同。

好消息是，您可以在@Import({FeignClientsConfiguration.class})中使用部分SpringCloud OpenFeign配置

同样，@RefreshScope也可以与这种方法一起使用。对于由@FeignClient注释创建的客户端，不可能使用@RefreshScope。

对于简单的情况，可以使用FeignClientBuilder。但是它对Feign的配置能力很差。

这些beans将从FeignClientsConfiguration导入

Decoder、Encoder、Contract、FeignLoggerFactory。

Contract用于使用像@PostMapping这样的Spring REST注解。

@Component
@RefreshScope
@Import({FeignClientsConfiguration.class})
class SomeClientFeign implements SomeClientApi {

    private static final boolean ALWAYS_FOLLOW_REDIRECTS = true;

    private final SomeConfig config;

    private final Decoder decoder;

    private final Encoder encoder;

    private final Contract contract;

    private final FeignLoggerFactory loggerFactory;

    private SomeClientApi clientApi;

    @Autowired
    public SomeClientFeign(SomeConfig config,
                           Decoder decoder, Encoder encoder,
                           Contract contract, FeignLoggerFactory loggerFactory) {
        this.config = config;
        this.decoder = decoder;
        this.encoder = encoder;
        this.contract = contract;
        this.loggerFactory = loggerFactory;
    }

    @PostConstruct
    private void createFeignClient() {
        Logger logger = loggerFactory.create(SomeClientApi.class);
        Logger.Level logLevel = config.isLogging() ? Logger.Level.FULL : Logger.Level.NONE;

        clientApi = Feign.builder()
                .client(client())
                .retryer(Retryer.NEVER_RETRY)
                .logger(logger)
                .logLevel(logLevel)
                .encoder(encoder).decoder(decoder).contract(contract)
                .options(requestOptions())
                .requestInterceptor(basicAuthRequestInterceptor())
                .target(SomeClientApi.class, config.getUrl());
    }

    private OkHttpClient client() {
        // to not recreate the client for each request, it is not important because the same dispatcher is used
        okhttp3.OkHttpClient client = new okhttp3.OkHttpClient.Builder()
                .connectTimeout(config.getConnectTimeoutMillis(), TimeUnit.MILLISECONDS)
                .readTimeout(config.getReadTimeoutMillis(), TimeUnit.MILLISECONDS)
                .followRedirects(ALWAYS_FOLLOW_REDIRECTS)
                .build();

        return new OkHttpClient(client);
    }

    private Request.Options requestOptions() {
        return new Request.Options(
                config.getConnectTimeoutMillis(), TimeUnit.MILLISECONDS,
                config.getReadTimeoutMillis(), TimeUnit.MILLISECONDS,
                ALWAYS_FOLLOW_REDIRECTS
        );
    }

    private BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
        return new BasicAuthRequestInterceptor(config.getUsername(), config.getPassword());
    }

    @Override
    public SomeResponse create(SomeRequest request) {
        return clientApi.createSomething(request);
    }

}