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Feign使用性能优化

Feign正确的使用方法和性能优化注意事项

1. feign自定义Configuration和root 容器有效隔离。

  • 用@Configuration注解
  • 不能在主@ComponentScan (or @SpringBootApplication)范围内,从其包名上分离
  • 注意避免包扫描重叠,最好的方法是明确的指定包名

2. Spring Cloud Netflix 提供了默认的Bean类型:

  • Decoder feignDecoder: ResponseEntityDecoder (which wraps a SpringDecoder)
  • Encoder feignEncoder: SpringEncoder
  • Logger feignLogger: Slf4jLogger
  • Contract feignContract: SpringMvcContract
  • Feign.Builder feignBuilder: HystrixFeign.Builder

3. Spring Cloud Netflix没有提供默认值,但仍然可以在feign上下文配置中创建:

  • Logger.Level
  • Retryer
  • ErrorDecoder
  • Request.Options
  • Collection

4. 自定义feign的消息编码解码器:

不要在如下代码中getObject方法内new 对象,外部会频繁调用getObject方法。

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ObjectFactory<HttpMessageConverters> messageConvertersObjectFactory = new ObjectFactory<HttpMessageConverters>() {
@Override
public HttpMessageConverters getObject() throws BeansException {
return httpMessageConverters;
}
};

5. 注意测试环境和生产环境,注意正确使用feign日志级别。

6. apacheHttpclient或者其他client的正确配置:

  • apacheHttpclient自定义配置放在spring root context,不要在FeignContext,否则不会起作用。
  • apacheHttpclient 连接池配置合理地连接和其他参数

7. Feign配置

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#Hystrix支持,如果为true,hystrix库必须在classpath中
feign.hystrix.enabled=false
#请求和响应GZIP压缩支持
feign.compression.request.enabled=true
feign.compression.response.enabled=true
#支持压缩的mime types
feign.compression.request.enabled=true
feign.compression.request.mime-types=text/xml,application/xml,application/json
feign.compression.request.min-request-size=2048
# 日志支持
logging.level.project.user.UserClient: DEBUG

8. Logger.Level支持

必须为每一个Feign Client配置来告诉Feign如何输出日志,可选:

  • NONE, No logging (DEFAULT).
  • BASIC, Log only the request method and URL and the response status code and execution time.
  • HEADERS, Log the basic information along with request and response headers.
  • FULL, Log the headers, body, and metadata for both requests and responses.

9. FeignClient.fallback 正确的使用方法

配置的fallback class也必须在FeignClient Configuration中实例化,否则会报 java.lang.IllegalStateException: No fallback instance of type class异常。

例子:

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@FeignClient(name = "hello", fallback = HystrixClientFallback.class)
public interface HystrixClient {
@RequestMapping(method = RequestMethod.GET, value = "/hello")
Hello iFailSometimes();
}
public class HystrixClientFallback implements HystrixClient {
@Override
public Hello iFailSometimes() {
return new Hello("fallback");
}
}
@Configuration
public class FooConfiguration {
@Bean
@Scope("prototype")
public Feign.Builder feignBuilder() {
return Feign.builder();
}
@Bean
public HystrixClientFallback fb(){
return new HystrixClientFallback();
}
}

10. 使用Feign Client 和@RequestMapping时,注意事项

当前工程中有和Feign Client中一样的Endpoint时,Feign Client的类上不能用@RequestMapping注解否则,当前工程该endpoint http请求且使用accpet时会报404.

下面的例子:

有一个 Controller

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@RestController
@RequestMapping("/v1/card")
public class IndexApi {
@PostMapping("balance")
@ResponseBody
public Info index() {
Info.Builder builder = new Info.Builder();
builder.withDetail("x", 2);
builder.withDetail("y", 2);
return builder.build();
}
}

有一个Feign Client

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@FeignClient(
name = "card",
url = "http://localhost:7913",
fallback = CardFeignClientFallback.class,
configuration = FeignClientConfiguration.class
)
@RequestMapping(value = "/v1/card")
public interface CardFeignClient {
@RequestMapping(value = "/balance", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
Info info();
}

if @RequestMapping is used on class, when invoke http /v1/card/balance, like this :

如果 @RequestMapping注解被用在FeignClient类上,当像如下代码请求/v1/card/balance时,注意有Accept header:

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Content-Type: application/json
Accept: application/json
POST http://localhost:7913/v1/card/balance

那么会返回 404。

如果不包含Accept header时请求,则是OK:

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Content-Type:application/json
POST http://localhost:7913/v1/card/balance

或者像下面不在Feign Client上使用@RequestMapping注解,请求也是ok,无论是否包含Accept:

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@FeignClient(
name = "card",
url = "http://localhost:7913",
fallback = CardFeignClientFallback.class,
configuration = FeignClientConfiguration.class
)
public interface CardFeignClient {
@RequestMapping(value = "/v1/card/balance", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
Info info();
}

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