创建名称为 'amazonS3Client' 的 bean 时出错：当前正在创建请求的 bean：是否存在无法解析的循环引用？

Question

一切都开始了，因为 Spring Cloud AWS 没有正确配置 SimpleStorageProtocolResolver。此 class 负责在使用 ResourceLoader 时处理 s3:// 协议。有关详细信息，请参阅问题：cannot be cast to org.springframework.core.io.WritableResource on Spring AWS example.

所以，我不得不手动创建它。但我也在使用 LocalStack 解决方案 (https://github.com/localstack/localstack)，并且由于 Spring Cloud AWS 没有手动配置端点的选项，我不得不（猜猜是什么？）创建 AmazonS3Client 手动.

问题来了，当我在 class S3Configuration class（见下文）中创建两个 bean 时，Spring 框架只是跳过 bean 创建。而且，当我尝试将它连接到 S3Handler class（见下文）时，会发生此错误：Error creating a bean with name 'amazonS3Client'：请求的 bean 当前正在创建中：是否存在无法解析的循环引用？

但是，又一次，整件事来了，那些 classes 之间没有循环引用。

我已经简化了项目，所以我可以在这里post它：

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 http://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>2.1.7.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>io.mobi7.ms</groupId>
    <artifactId>mobi7-temp-ms-ibutton-worker</artifactId>
    <version>1.0.0-SNAPSHOT</version>

    <properties>
        <spring-cloud-version>2.1.4.RELEASE</spring-cloud-version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-aws</artifactId>
            <version>${spring-cloud-version}</version>
        </dependency>
    </dependencies>

</project>

S3Configuration.java

package io.mobi7.ms.ibutton.worker;

import com.amazonaws.auth.AWSCredentialsProvider;
import com.amazonaws.client.builder.AwsClientBuilder;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.aws.core.io.s3.SimpleStorageProtocolResolver;
import org.springframework.cloud.aws.core.region.RegionProvider;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.DefaultResourceLoader;

@Configuration
public class S3Configuration {

    @Bean("amazonS3Client") // THIS METHOD IS NOT BEING CALLED!!!
    public AmazonS3 amazonS3Client(AWSCredentialsProvider credentialsProvider,
                                   RegionProvider regionProvider,
                                   @Value("${cloud.aws.s3.default-endpoint}") String endpoint) {
        return AmazonS3ClientBuilder.standard()
            .withCredentials(credentialsProvider)
            .withEndpointConfiguration(
                new AwsClientBuilder.EndpointConfiguration(endpoint, regionProvider.getRegion().getName()))
            .build();
    }

    @Autowired  // THIS METHOD IS NOT BEING CALLED!!!
    public void configureResourceLoader(@Qualifier("amazonS3Client") AmazonS3 amazonS3Client,
                                        DefaultResourceLoader resourceLoader) {
        SimpleStorageProtocolResolver simpleStorageProtocolResolver = new SimpleStorageProtocolResolver(amazonS3Client);
        // As we are calling it by hand, we must initialize it properly.
        simpleStorageProtocolResolver.afterPropertiesSet();
        resourceLoader.addProtocolResolver(simpleStorageProtocolResolver);
    }
}

S3Handle.java

package io.mobi7.ms.ibutton.worker;

import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.model.S3ObjectSummary;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.stream.Collectors;

@Component
public class S3Handler {

    private AmazonS3 amazonS3Client;

    @Autowired
    public S3Handler(@Qualifier("amazonS3Client") AmazonS3 amazonS3Client) {
        this.amazonS3Client = amazonS3Client;
    }

    public List<String> listFiles(String bucketName) {
        return amazonS3Client.listObjects(bucketName).getObjectSummaries().stream().map(S3ObjectSummary::getKey)
            .collect(Collectors.toList());
    }
}

Application.java

package io.mobi7.ms.ibutton.worker;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(WebApplicationType.NONE).run(args);
    }

    @Autowired
    public void listFiles(S3Handler s3Handler) {
        s3Handler.listFiles("default-s3-bucket").forEach(System.out::println);
    }
}

application.properties

cloud.aws.region.static=us-east-1
cloud.aws.stack.auto=false
cloud.aws.s3.default-endpoint=http://localhost:4572

任何想法，为什么会这样？

Answer 1

@Autowired注解标记了构造对象状态的方法（例如setter或方法注入）。请参阅 "Autowired Methods" 部分 here。

您使用 Autowired 注释的两种方法均未用于此需求。

这个问题是关于Spring的。可以删除所有其他标签。

更新： 涵盖了类似案例。
不管那里的建议是什么，我都不会保留单个 GOD 配置 class，而是将您的配置 class 拆分为 2 classes - S3 客户端的工厂和资源加载器的配置.

创建名称为 'amazonS3Client' 的 bean 时出错：当前正在创建请求的 bean：是否存在无法解析的循环引用？

Error creating bean with name 'amazonS3Client': Requested bean is currently in creation: Is there an unresolvable circular reference?

spring

spring-boot

spring-cloud-aws