详解Spring Cloud Feign 熔断配置的一些小坑

时间:2021-10-29 15:11:30

1.在使用feign做服务调用时,使用继承的方式调用服务,加入hystrix的熔断处理fallback配置时,会报错,已解决。 2.使用feign默认配置,熔断不生效,已解决。

最近在做微服务的学习,发现在使用feign做服务调用时,使用继承的方式调用服务,加入hystrix的熔断处理fallback配置时,会报错,代码如下:

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@requestmapping("/demo/api")
public interface helloapi {
 
  @getmapping("user/{id}")
  user getuserbyid(@pathvariable("id") long id);
 
  @getmapping("hello")
  string echo(@requestparam("name") string name);
}
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@feignclient(value = "ms-server", fallback = consumerfeignservicefallback.class)
public interface consumerfeignservice extends helloapi {
 
}
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@component
public class consumerfeignservicefallback implements consumerfeignservice {
  @override
  public user getuserbyid(long id) {
    return new user();
  }
 
  @override
  public string echo(string name) {
    return "echo error: " + name;
  }
}

报错如下:

caused by: java.lang.illegalstateexception: ambiguous mapping. cannot map 'com.thoughtworks.demo.consumer.service.consumerfeignservice' method
public abstract java.lang.string com.thoughtworks.demo.api.helloapi.echo(java.lang.string)
to {[/demo/api/hello],methods=[get]}: there is already 'consumerfeignservicefallback' bean method
public java.lang.string com.thoughtworks.demo.consumer.service.consumerfeignservicefallback.echo(java.lang.string) mapped.
 at org.springframework.web.servlet.handler.abstracthandlermethodmapping$mappingregistry.assertuniquemethodmapping(abstracthandlermethodmapping.java:576) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.web.servlet.handler.abstracthandlermethodmapping$mappingregistry.register(abstracthandlermethodmapping.java:540) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.web.servlet.handler.abstracthandlermethodmapping.registerhandlermethod(abstracthandlermethodmapping.java:264) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.web.servlet.handler.abstracthandlermethodmapping.detecthandlermethods(abstracthandlermethodmapping.java:250) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.web.servlet.handler.abstracthandlermethodmapping.inithandlermethods(abstracthandlermethodmapping.java:214) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.web.servlet.handler.abstracthandlermethodmapping.afterpropertiesset(abstracthandlermethodmapping.java:184) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.web.servlet.mvc.method.annotation.requestmappinghandlermapping.afterpropertiesset(requestmappinghandlermapping.java:127) ~[spring-webmvc-4.3.14.release.jar:4.3.14.release]
 at org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.invokeinitmethods(abstractautowirecapablebeanfactory.java:1687) ~[spring-beans-4.3.14.release.jar:4.3.14.release]
 at org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.initializebean(abstractautowirecapablebeanfactory.java:1624) ~[spring-beans-4.3.14.release.jar:4.3.14.release]
 ... 21 common frames omitted

错误原因是这里继承的接口类是一个controller接口,继承时会继承到父类的

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@requestmapping("/demo/api")

springmvc在做mapping映射的时候发现consumerfeignservice和consumerfeignservicefallback的mapping重复了,所以抛出异常,如何解决呢?

解决的方法有2个:

一是更改consumerfeignservicefallback的mapping配置,代码如下:

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@component
@requestmapping("fallback/demo/api")
public class consumerfeignservicefallback implements consumerfeignservice {
  @override
  public user getuserbyid(long id) {
    return new user();
  }
 
  @override
  public string echo(string name) {
    return "echo error: " + name;
  }
}

二是使用fallbackfactory,代码如下:

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@component
public class consumerfeignservicefallback implements fallbackfactory<consumerfeignservice> {
 
  @override
  public consumerfeignservice create(throwable cause) {
    return new consumerfeignservice() {
      @override
      public user getuserbyid(long id) {
        return new user();
      }
 
      @override
      public string echo(string name) {
        return "echo error: " + name;
      }
    };
  }
}

运行后,关闭服务提供者,发现熔断并没有生效,没有像单独使用@hystrixcommand时进入fallback方法,查了很多方式,发现原来是feign的hystix的配置开关没有打开

解决方法,在application.yml中增加配置如下:

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feign:
 hystrix:
  enabled: true

在intellij idea里也没有这个配置的提示,还报告警告,不知道算不算是个bug,这里我使用的版本是

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springbootversion = '1.5.10.release'
springcloudversion = 'edgware.sr3'

以上就是我在使用feign时发现的一些小坑,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。

原文链接:https://my.oschina.net/u/1758970/blog/1798279