java.lang.NoClassDefFoundError: feign/Request$Options

Question

我正在使用 Spring Boot 创建项目，尝试使用 feign 在多个微服务之间进行通信。我已经添加了 @EnableFeignClients 在 spring 应用程序上，但是一旦我添加 @FeignClient 来创建 feign 客户端，我就会收到“java.lang.NoClassDefFoundError: feign/Request$Options”异常。

CurrencyConversionServiceApplication.class ：

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

@SpringBootApplication
@EnableFeignClients
public class CurrencyConversionServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(CurrencyConversionServiceApplication.class, args);
    }
}

CurrencyExchangeProxy.class：

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import com.pavan.microservices.currencyconversionservice.bean.CurrencyConversion;

@FeignClient(value="currency-exchange",name="currency-exchange", url="localhost:8000")
public interface CurrencyExchangeProxy {

    @GetMapping("/currency-exchange/from/{from}/to/{to}")
    public CurrencyConversion retrieveExchangeValue(@PathVariable String from, @PathVariable String to);    
}

pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.1</version>        
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.pavan.microservices</groupId>
    <artifactId>currency-conversion-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>currency-conversion-service</name>
    <description>Currency Conversion Service</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </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>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

启动应用程序时出错：

java.lang.NoClassDefFoundError: feign/Request$Options
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.<init>(FeignClientFactoryBean.java:104) ~[spring-cloud-openfeign-core-3.1.0.jar:3.1.0]
    at org.springframework.cloud.openfeign.FeignClientsRegistrar.registerFeignClient(FeignClientsRegistrar.java:215) ~[spring-cloud-openfeign-core-3.1.0.jar:3.1.0]
    at org.springframework.cloud.openfeign.FeignClientsRegistrar.registerFeignClients(FeignClientsRegistrar.java:202) ~[spring-cloud-openfeign-core-3.1.0.jar:3.1.0]
    at org.springframework.cloud.openfeign.FeignClientsRegistrar.registerBeanDefinitions(FeignClientsRegistrar.java:151) ~[spring-cloud-openfeign-core-3.1.0.jar:3.1.0]
    at org.springframework.context.annotation.ImportBeanDefinitionRegistrar.registerBeanDefinitions(ImportBeanDefinitionRegistrar.java:86) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.lambda$loadBeanDefinitionsFromRegistrars$1(ConfigurationClassBeanDefinitionReader.java:396) ~[spring-context-5.3.13.jar:5.3.13]
    at java.util.LinkedHashMap.forEach(Unknown Source) ~[na:1.8.0_73]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsFromRegistrars(ConfigurationClassBeanDefinitionReader.java:395) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:157) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:129) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:343) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:247) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:311) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:112) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:746) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:564) ~[spring-context-5.3.13.jar:5.3.13]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.1.jar:2.6.1]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) [spring-boot-2.6.1.jar:2.6.1]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) [spring-boot-2.6.1.jar:2.6.1]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:302) [spring-boot-2.6.1.jar:2.6.1]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) [spring-boot-2.6.1.jar:2.6.1]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1290) [spring-boot-2.6.1.jar:2.6.1]
    at com.pavan.microservices.currencyconversionservice.CurrencyConversionServiceApplication.main(CurrencyConversionServiceApplication.java:12) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_73]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_73]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_73]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_73]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.6.1.jar:2.6.1]
Caused by: java.lang.ClassNotFoundException: feign.Request$Options
    at java.net.URLClassLoader.findClass(Unknown Source) ~[na:1.8.0_73]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.8.0_73]
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) ~[na:1.8.0_73]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.8.0_73]
    ... 28 common frames omitted

Answer 1

我在跟进 In28Minutes 春季微服务课程时也遇到了这个问题。

我注意到 Fiegn jar 下的 Request 类未正确加载，因此出现此错误。

我认为 maven 无法正确下载 jar。

所以我删除了“我的主目录”/.m2 下可用的 .m2 文件夹，例如 C:/Users/userName/.m2 然后在 eclipse 中选择项目 >> 右键单击​​ >> Maven >> 更新项目>> 选择 Force Update of Snapshots/Releases 并点击 OK。

它再次下载maven依赖并能够在eclipse中启动服务而不会出现此错误。

这次可以在eclipse中打开Request类了。