feign改写默认编码器

可以通过继承Feign的Encoder.Default编码器类，并重写其encode方法来改写默认编码器。

重写的示例代码如下：

public class CustomEncoder extends Encoder.Default {
    private final Gson gson;

    public CustomEncoder(ObjectFactory objectFactory) {
        this.gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
    }

    @Override
    public void encode(Object object, Type bodyType, RequestTemplate template) throws EncodeException {
        if (bodyType != null && object != null) {
            if (bodyType instanceof Class && (MediaType.APPLICATION_JSON_VALUE.equals(template.headers().get("Content-Type")) || MediaType.APPLICATION_JSON_VALUE.equals(template.headers().get("content-Type")))) {
                String json = gson.toJson(object, bodyType);
                template.body(json);
            }
        }
    }
}

在Feign客户端接口中使用自定义编码器：

@FeignClient(name = "myService", configuration = MyFeignConfiguration.class)
public interface MyFeignClient {

    @PostMapping(value = "/api/test", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
    ResultVO<String> test(@RequestBody TestDTO testDTO);

}

在配置类中配置自定义编码器：

@Configuration
public class MyFeignConfiguration {

    @Bean
    public Encoder encoder() {
        return new CustomEncoder(new SpringEncoder(new DefaultJackson2ObjectMapperBuilder()));
    }

}