Spring boot - 单个 @Configuration @import 可以工作，但多个不会，为什么？

Question

在 Spring 启动项目中，我有一个 RestController，其中包含：

@Autowired
private ProactiveDbManager proactiveDbManager;

@Autowired
private CoreDbManager coreDbManager;

这些 2 数据库管理器位于另一个 Spring 引导模块中，因此我使用配置类导入它们：

@Configuration
@PropertySource("classpath:application.properties")
@Import({ProactiveDbCommonsConfig.class})
public class ProactiveDbConfig {

}

和：

@Configuration
@PropertySource("classpath:application.properties")
@Import({CoreDbCommonsConfig.class})
public class CoreDbConfig {

}

ProactiveDbCommonsConfig 和 CoreDbCommonsConfig 也是配置。 ProactiveDbCommonsConfig:

@Configuration
public class ProactiveDbCommonsConfig {
    private static final Logger LOGGER = LoggerFactory.getLogger(ProactiveDbCommonsConfig.class);

    private ProactiveDbManager proactiveDbManager;
    @Bean
    public MasterHandler masterHandler() {
        return new MasterHandler(true);
    }

    @Bean
    public ProactiveDbManager dBManager(MasterHandler masterHandler) {
        List<String> dbConnectionStrings = masterHandler.getDbConnectionStringsJsonsList(DbConsts.DEFAULT_DATA_CENTER);
        LOGGER.debug("DB manager created.");
        proactiveDbManager = new ProactiveDbManager(dbConnectionStrings);
        return proactiveDbManager;
    }


    @Override
    protected void finalize() {
        try {
            closeDbConnection();
        } catch (Exception ignored) {
        }
    }

    @PreDestroy
    public void closeDbConnection() throws Exception {
        if (this.proactiveDbManager != null) {
            this.proactiveDbManager.disconnect();
            this.proactiveDbManager = null;
        }
    }
}

我的问题是，如果我删除控制器中的 1 个自动接线并删除其配置（即ProactiveDbConfig），那么它就可以工作。他们两个都单独工作，但不能一起工作。

我得到的错误是：

Field coreDbManager in x.y.z.controllers.h required a bean of type 'x.y.a.db.managers.CoreDbManager' that could not be found.

堆栈跟踪：

15:56:14.609 [main] DEBUG o.s.b.d.LoggingFailureAnalysisReporter - Application failed to start due to an exception
org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'x.y.db.managers.CoreDbManager' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1493)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107)
    at x.y.app.MyApp.main(MyApp.java:10)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.CommandLineWrapper.main(CommandLineWrapper.java:66)
15:56:14.609 [main] ERROR o.s.b.d.LoggingFailureAnalysisReporter - 

Answer 1

当使用@Configuration 类并且没有在@Bean(name = "<your-name-here>") 中明确定义bean 的名称时，methodname 将用作bean 的名称。

如果您导入多个包含同名 bean 的配置文件，其中一个将覆盖另一个。较新版本的 Spring Boot 通过禁用覆盖（默认启用）来防止这种情况，这将在启动时导致异常。

在您的情况下，解决方案是重命名方法或将显式名称添加到 @Bean 注释。