最近要接入神策埋点，数据采集接入的话，API接入部分，使用feign api方式调用

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How does Feign work?
Feign works by processing annotations into a templatized request. Arguments are applied to these templates in a straightforward fashion before output. Although Feign is limited to supporting text-based APIs, it dramatically simplifies system aspects such as replaying requests. Furthermore, Feign makes it easy to unit test your conversions knowing this.

文档指南：

https://github.com/OpenFeign/feign

为什么要使用feign呢？

feign的扩展：

提高扩展性，使用者可以不修改框架源码的情况下，为框架扩展新的功能（类似于插件模式）
feign 是一个 HTTP 客户端框架，我们可以在不修改框架源码的情况下，用如下方式来扩展我们自己的编解码方式、日志、拦截器等。

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Feign feign = Feign.builder()
        .logger(new CustomizedLogger())
        .encoder(new FormEncoder(new JacksonEncoder()))
        .decoder(new JacksonDecoder())
        .errorDecoder(new ResponseErrorDecoder())
        .requestInterceptor(new RequestHeadersInterceptor()).build();

public class RequestHeadersInterceptor implements RequestInterceptor {  
  @Override
  public void apply(RequestTemplate template) {
    template.header("appId", "...");
    template.header("version", "...");
    template.header("timestamp", "...");
    template.header("token", "...");
    template.header("idempotent-token", "...");
    template.header("sequence-id", "...");
}

public class CustomizedLogger extends feign.Logger {
  //...
}

public class ResponseErrorDecoder implements ErrorDecoder {
  @Override
  public Exception decode(String methodKey, Response response) {
    //...
  }
}

other cases

A

hystrix - https://github.com/Netflix/Hystrix
降级方案 - 系统之间feign调用

B

  • sentinel - 资源|规则 - 流量控制-自由选择控制的角度，灵活组合，从而达到想要的效果 -熔断降级-降低调用链路中的不稳定资源 - 系统负载保护
  • sentinel(面向分布式服务架构的流量控制组件) - 适配feign
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    feign.sentinel.enable=true
    error
    NoSuchMethodErrorfeign.RequestTemplate.path（）Ljava / lang / String;
    版本不匹配 - spring-cloud-starter-alibaba-sentinel feign-core
    解决 - 添加流量规则
    Method：http://service-name/path

C

okhttp3性能 > httpclient
feign底层 更换为 okhttp3