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SpringCloud中FeignClient自定义配置

2025-08-15 11:19:05 作者：一乐小哥

使用FeignClient时需了解其默认配置机制,通过注入Decoder、Encoder等Bean实现自定义配置,下面就来介绍一下如何使用,感兴趣的可以了解一下

前言

最近公司新老项目对接过程中使用feginClient进行调用时遇到了很多问题,在此做些简短的总结记录

一、Feign的配置原理

当我们配置一个feignClient的时候,通常的写法是这样的

@FeignClient("xxxClient")
public interface xxxClient{
}

当我们做这个实际上就是生成一个默认的FeignClient, 其配置在org.springframework.cloud.openfeign 包下的FeignClientsConfiguration

@Configuration
public class FeignClientsConfiguration {
	@Autowired
	private ObjectFactory<HttpMessageConverters> messageConverters;
	@Autowired(required = false)
	private List<AnnotatedParameterProcessor> parameterProcessors = new ArrayList<>();
	@Autowired(required = false)
	private List<FeignFormatterRegistrar> feignFormatterRegistrars = new ArrayList<>();
	@Autowired(required = false)
	private Logger logger;
	@Bean
	@ConditionalOnMissingBean
	public Decoder feignDecoder() {
		return new OptionalDecoder(new ResponseEntityDecoder(new SpringDecoder(this.messageConverters)));
	}
	@Bean
	@ConditionalOnMissingBean
	public Encoder feignEncoder() {
		return new SpringEncoder(this.messageConverters);
	}
	@Bean
	@ConditionalOnMissingBean
	public Contract feignContract(ConversionService feignConversionService) {
		return new SpringMvcContract(this.parameterProcessors, feignConversionService);
	}
	@Bean
	public FormattingConversionService feignConversionService() {
		FormattingConversionService conversionService = new DefaultFormattingConversionService();
		for (FeignFormatterRegistrar feignFormatterRegistrar : feignFormatterRegistrars) {
			feignFormatterRegistrar.registerFormatters(conversionService);
		}
		return conversionService;
	}

	@Configuration
	@ConditionalOnClass({ HystrixCommand.class, HystrixFeign.class })
	protected static class HystrixFeignConfiguration {
		@Bean
		@Scope("prototype")
		@ConditionalOnMissingBean
		@ConditionalOnProperty(name = "feign.hystrix.enabled")
		public Feign.Builder feignHystrixBuilder() {
			return HystrixFeign.builder();
		}
	}
	@Bean
	@ConditionalOnMissingBean
	public Retryer feignRetryer() {
		return Retryer.NEVER_RETRY;
	}
	@Bean
	@Scope("prototype")
	@ConditionalOnMissingBean
	public Feign.Builder feignBuilder(Retryer retryer) {
		return Feign.builder().retryer(retryer);
	}
	@Bean
	@ConditionalOnMissingBean(FeignLoggerFactory.class)
	public FeignLoggerFactory feignLoggerFactory() {
		return new DefaultFeignLoggerFactory(logger);
	}
}

可以看到这上面所有注入的bean都有一个注解@ConditionalOnMissingBean,也就没有自定义则触发创建Bean

这一段Bean的注入在FeignClientFactoryBean中的这段代码, 当服务启动时触发

protected Feign.Builder feign(FeignContext context) {
		FeignLoggerFactory loggerFactory = get(context, FeignLoggerFactory.class);
		Logger logger = loggerFactory.create(type);

		// @formatter:off 从spring上下文中获取对应的Bean
		Feign.Builder builder = get(context, Feign.Builder.class)
				// required values
				.logger(logger)
				.encoder(get(context, Encoder.class))
				.decoder(get(context, Decoder.class))
				.contract(get(context, Contract.class));
		// @formatter:on

		configureFeign(context, builder);

		return builder;
	}

二、自定义配置

这就意味着如果我们需要自定义FeignClient的相关配置可以直接注入其中一个bean就可以了

类似于

@Configuration
public class FeignClientsConfiguration {

    @Bean
    public Decoder feignDecoder() {
        return new ResultDecoder();
    }

    @Bean
    public Encoder feignEncoder() {
        return new ParamEncoder();
    }

    @Bean
    public Contract feignContract() {
        return new DefaultContract();
    }
}

如上所示, 我分别注入了Decoder、Encoder、Contract, 而其他几项依然还是feign默认值.

三、专有配置

那么如果我想为一个client单独加一些配置又应该如何做呢?

点开@FeignClient可以看到里面有一项configuration

/**
	 * A custom <code>@Configuration</code> for the feign client. Can contain override
	 * <code>@Bean</code> definition for the pieces that make up the client, for instance
	 * {@link feign.codec.Decoder}, {@link feign.codec.Encoder}, {@link feign.Contract}.
	 *
	 * @see FeignClientsConfiguration for the defaults
	 */
	Class<?>[] configuration() default {};

所以我们可以写一个如下的configuration

public class SelfFeignClientsConfiguration {
    @Bean
    @ConditionalOnMissingBean(name = "SelfFeignDecoder")
    public Decoder SelfFeignDecoder() {
        return new JacksonDecoder();
    }
}

再在feignClient上引入

@FeignClient(name = "xxxClient", configuration = SelfFeignClientsConfiguration.class)
public interface xxxClient{
}

如此即可完成对xxxClient更细粒度的配置.

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SpringCloud中FeignClient自定义配置

前言

一、Feign的配置原理

二、自定义配置

三、专有配置

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