Spring Cloud Feign基本配置与使用教程-优快云博客

本文链接：https://blog.youkuaiyun.com/lilyssh/article/details/119776678

本文介绍了如何在Spring Cloud中使用Feign进行服务调用。首先，文章强调了Spring Boot和Spring Cloud版本匹配的重要性，指出版本不对应会导致Feign依赖导入失败。接着，详细说明了在启动类中添加注解以启用Feign扫描，以及编写Feign接口的步骤。最后，针对启动报错问题，提示检查SpringCloud版本，并成功解决问题。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

一、调用方：

1、导入依赖

可能会出现的坎坷：

（1）feign依赖导入失败

可能的原因：spring cloud 与 spring boot 的版本是有对应关系的，如果两者不对应，就会导入失败，报红。
具体对应关系查询请移步：
https://www.jianshu.com/p/a452c45c8937

比如我的spring boot用得是2.0.3 主版本号.子版本号.修正版本号

<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.3.RELEASE</version>
		<relativePath/> 
	</parent>

那我的spring cloud就得用Finchley.SR4 主版本号.子版本号.修正版本号.软件版本阶段

<properties>
	<spring-cloud.version>Finchley.SR4</spring-cloud.version>
</properties>

<dependencies>
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-openfeign</artifactId>
	</dependency>
</dependencies>

<dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-dependencies</artifactId>
			<version>${spring-cloud.version}</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>

2、启动类新增`@EnableFeignClients`注解，开启 Feign 扫描支持，如：

package cn.xxx.sppointsproxyservice;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class SpPointsProxyServiceApplication {

	public static void main(String[] args) {
		//解决es  netty冲突问题
		System.setProperty("es.set.netty.runtime.available.processors", "false");
		SpringApplication.run(SpPointsProxyServiceApplication.class, args);
	}

}

3、Feign 接口编写，接口新增`@FeignClient`注解。如：

package cn.xxx.sppointsproxyservice.feign;

import cn.xxx.sppointsproxyservice.config.FeignConfig;
import cn.xxx.sppointsproxyservice.hystrix.UserServiceHystrix;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.*;

@FeignClient(name = "OP-ACCOUNT-SERVICE", configuration = FeignConfig.class, fallback = UserServiceHystrix.class)
public interface UserFeign {

    @RequestMapping(value = "/login/{partnerCode}/{stbId}/{mac}/", method = RequestMethod.GET)
    String userLogin(@PathVariable("partnerCode") @RequestHeader("partnerCode") String partnerCode,
                     @PathVariable("stbId") String stbId,
                     @PathVariable("mac") String mac);

}

@FeignClient中的name需与被调用方的spring.application.name保持一致，忽略大小写。

二、测试：

启动报错：

2021-08-18 16:29:30.068 [main] WARN  o.s.b.w.s.c.AnnotationConfigServletWebServerApplicationContext - Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [cn.gitv.sppointsproxyservice.SpPointsProxyServiceApplication]; nested exception is java.lang.IllegalArgumentException: Could not find class [org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition]
2021-08-18 16:29:30.084 [main] ERROR org.springframework.boot.SpringApplication - Application run failed
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [cn.gitv.sppointsproxyservice.SpPointsProxyServiceApplication]; nested exception is java.lang.IllegalArgumentException: Could not find class [org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition]
	at org.springframework.context.annotation.ConfigurationClassParser.processImports(ConfigurationClassParser.java:648)
	at org.springframework.context.annotation.ConfigurationClassParser.lambda$processDeferredImportSelectors$2(ConfigurationClassParser.java:567)
	at java.util.ArrayList.forEach(ArrayList.java:1259)
	at org.springframework.context.annotation.ConfigurationClassParser.processDeferredImportSelectors(ConfigurationClassParser.java:563)
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:188)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:316)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:233)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:273)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:93)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:694)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:327)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243)
	at cn.gitv.sppointsproxyservice.SpPointsProxyServiceApplication.main(SpPointsProxyServiceApplication.java:20)
Caused by: java.lang.IllegalArgumentException: Could not find class [org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:313)
	at org.springframework.context.annotation.ConditionEvaluator.getCondition(ConditionEvaluator.java:124)
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:96)
	at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:221)
	at org.springframework.context.annotation.ConfigurationClassParser.processMemberClasses(ConfigurationClassParser.java:362)
	at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:265)
	at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:245)
	at org.springframework.context.annotation.ConfigurationClassParser.processImports(ConfigurationClassParser.java:638)
	... 17 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition
	at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
	at org.springframework.util.ClassUtils.forName(ClassUtils.java:274)
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:310)
	... 24 common frames omitted
Disconnected from the target VM, address: '127.0.0.1:51616', transport: 'socket'

Process finished with exit code 1

摘出关键信息：

Could not find class [org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition]

ClassNotFoundException: OnNoRibbonDefaultCondition

pom.xml中SpringCloud版本不对，换成上面所说的正确的版本后，再次测试：
在这里插入图片描述大功告成！

附：SpringCloud 版本号说明：

第一代：Angle，
第二代：Brixton；
第三代：Camden，
第四代：Dalston；
第五代：Edgware，
第六代：Finchley；
第七代：GreenWich，
第八代：Hoxton；

snapshot 快照
alpha 内测
beta 公测
release 稳定版本
GA 最稳定版本
Final 正式版
Pro(professional) 专业版
Plus 加强版
Retail 零售版
DEMO 演示版
Build 内部标号
Delux 豪华版 （deluxe：豪华的，华丽的）
Corporation或Enterpraise 企业版
M1（Milestone） 里程碑
RC（Release Candidate）几乎就不会加入新的功能了，而主要着重于除错
SR（Service Release）修正版  （对于release版本的问题进行修复）
Trial 试用版
Shareware 共享版
Full 完全版