Spring Cloud Gateway断路器步骤启动失败：缺失指定Bean

按照官方指南操作Spring Cloud Gateway，在添加断路器路由配置后启动应用报错，此前仅添加Hello World过滤器的步骤可正常运行，已尝试Java 8和Java 17版本，问题一致。

添加的断路器路由代码 #

@Bean
public RouteLocator myRoutes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route(p -> p
            .path("/get")
            .filters(f -> f.addRequestHeader("Hello", "World"))
            .uri("http://httpbin.org:80"))
        .route(p -> p
            .host("*.circuitbreaker.com")
            .filters(f -> f.circuitBreaker(config -> config.setName("mycmd")))
            .uri("http://httpbin.org:80")).
        build();
}

启动报错信息 #

***************************
APPLICATION FAILED TO START
***************************

Description:

Method myRoutes in com.example.springcloudgatewaypoc.Application required a bean of type 'org.springframework.cloud.gateway.filter.factory.SpringCloudCircuitBreakerFilterFactory' that could not be found.


Action:

Consider defining a bean of type 'org.springframework.cloud.gateway.filter.factory.SpringCloudCircuitBreakerFilterFactory' in your configuration.

完整应用代码 #

package com.example.springcloudgatewaypoc;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.gateway.route.RouteLocator;
import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class Application {

  @Bean
  public RouteLocator myRoutes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route(p -> p
            .path("/get")
            .filters(f -> f.addRequestHeader("Hello", "World"))
            .uri("http://httpbin.org:80"))
        .route(p -> p
            .host("*.circuitbreaker.com")
            .filters(f -> f.circuitBreaker(config -> config.setName("mycmd")))
            .uri("http://httpbin.org:80")).
        build();
  }

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

Java 1.8对应的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>2.7.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>spring-cloud-gateway-poc</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-cloud-gateway-poc</name>
    <description>Demo project for Spring Cloud Gateway</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>2021.0.4</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-circuitbreaker-resilience4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-contract-stub-runner</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>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.7.4</version>
            </plugin>
        </plugins>
    </build>

</project>

解决方案 #

问题根源是依赖适配问题：Spring Cloud Gateway基于WebFlux响应式编程模型，需要使用Reactor版本的断路器依赖，而非普通的Resilience4J断路器依赖。你的pom.xml中仅在dependencyManagement中声明了spring-cloud-starter-circuitbreaker-reactor-resilience4j，但未在dependencies块中引入，同时错误引入了非响应式的spring-cloud-starter-circuitbreaker-resilience4j。

修正步骤：

1. 删除dependencies中的spring-cloud-starter-circuitbreaker-resilience4j依赖
2. 在dependencies中添加spring-cloud-starter-circuitbreaker-reactor-resilience4j依赖

修正后的dependencies块如下：

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

同时可以移除dependencyManagement中单独声明的spring-cloud-starter-circuitbreaker-reactor-resilience4j，因为spring-cloud-dependencies已经管理了该依赖的版本。

内容的提问来源于stack exchange，提问作者techieIntern