Question

我开发了一个自定义Spring Boot自动配置，以便于使用专有的消息传递库。

主要的自动配置类基本如下：

@Configuration
@ConditionalOnClass({LibServer.class, LibClient.class})
@EnableConfigurationProperties(LibProperties.class)
public class LibAutoConfiguration {

    @Autowired
    LibProperties props;

    @Bean
    @ConditionalOnMissingBean(LibServer.class)
    public LibServer lbServ() {
        // create and configure a server object
    }

    @Bean
    @ConditionalOnMissingBean(LibClient.class)
    public LibClient lbClient() {
        //create and configure a client object
    }
}

然而，条件注释似乎没有检测到主@SpringBootApplication注释类中声明的bean。

它只检测在单独的@Configuration注释类中声明的bean。

也就是说，如果我放置两个@Bean带注释的方法，在主类中返回LibServer和LibClient个对象，我最终得到两个LibServer和两个{ {1}}上下文中的对象（自动配置的和明确声明的对象）。

本机spring引导自动配置（例如LibClient one）也可以检测主类中声明的bean（例如DataSource带注释的@Bean方法）。

即使是在主类中声明的bean，我如何获得正确的bean检测？

修改

展示行为的完整多模块maven项目位于https://github.com/AlexFalappa/spring-boot-testcase

Answer 1

如果在application.properties（logging.level.org.springframework=DEBUG）中设置调试日志级别，您会注意到Spring将检测这两个定义。但是你也会看到the order in which this happens may not be what you expected，因为它首先从库配置实例化bean，然后从主类实例化AFTERWARDS，因此你得到2个实例（剥离时间戳使其更友好）：

Bean定义

o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'autoConfigurationReport'
a.ConfigurationClassBeanDefinitionReader : Registering bean definition for @Bean method af.spring.boot.libbo.LibAutoConfiguration.lbServ()
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'org.springframework.boot.autoconfigure.condition.BeanTypeRegistry'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'autoConfigurationReport'
a.ConfigurationClassBeanDefinitionReader : Registering bean definition for @Bean method af.spring.boot.libbo.LibAutoConfiguration.lbClient()
a.ConfigurationClassBeanDefinitionReader : Registering bean definition for @Bean method af.DemoLibboApplication.libServ()
a.ConfigurationClassBeanDefinitionReader : Registering bean definition for @Bean method af.DemoLibboApplication.libClient()

Bean实例化

o.s.b.f.s.DefaultListableBeanFactory     : Creating shared instance of singleton bean 'lbServ'
o.s.b.f.s.DefaultListableBeanFactory     : Creating instance of bean 'lbServ'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'libAutoConfiguration'
Autoconfiguring LibServer
o.s.b.f.s.DefaultListableBeanFactory     : Eagerly caching bean 'lbServ' to allow for resolving potential circular references
o.s.b.f.s.DefaultListableBeanFactory     : Finished creating instance of bean 'lbServ'
o.s.b.f.s.DefaultListableBeanFactory     : Creating shared instance of singleton bean 'lbClient'
o.s.b.f.s.DefaultListableBeanFactory     : Creating instance of bean 'lbClient'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'libAutoConfiguration'
Autoconfiguring LibClient
o.s.b.f.s.DefaultListableBeanFactory     : Eagerly caching bean 'lbClient' to allow for resolving potential circular references
o.s.b.f.s.DefaultListableBeanFactory     : Finished creating instance of bean 'lbClient'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'lib.CONFIGURATION_PROPERTIES'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.store'
o.s.b.f.s.DefaultListableBeanFactory     : Creating shared instance of singleton bean 'libServ'
o.s.b.f.s.DefaultListableBeanFactory     : Creating instance of bean 'libServ'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'demoLibboApplication'
o.s.b.f.s.DefaultListableBeanFactory     : Eagerly caching bean 'libServ' to allow for resolving potential circular references
o.s.b.f.s.DefaultListableBeanFactory     : Finished creating instance of bean 'libServ'
o.s.b.f.s.DefaultListableBeanFactory     : Creating shared instance of singleton bean 'libClient'
o.s.b.f.s.DefaultListableBeanFactory     : Creating instance of bean 'libClient'
o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'demoLibboApplication'
o.s.b.f.s.DefaultListableBeanFactory     : Eagerly caching bean 'libClient' to allow for resolving potential circular references
o.s.b.f.s.DefaultListableBeanFactory     : Finished creating instance of bean 'libClient'

您还可以在AUTO-CONFIGURATION REPORT中查看当前实现中评估LibAutoConfiguration中的条件时，它们是否匹配，通常会创建bean：

Positive matches:
-----------------
...
LibAutoConfiguration#lbClient matched
  - @ConditionalOnMissingBean (types: af.libbo.LibClient; SearchStrategy: all) found no beans (OnBeanCondition)

LibAutoConfiguration#lbServ matched
  - @ConditionalOnMissingBean (types: af.libbo.LibServer; SearchStrategy: all) found no beans (OnBeanCondition)
...

但是，如果您向主类添加相同的条件，您将看到它将根据LibAutoConfiguration中的定义创建bean，并在尝试时为DemoLibboApplication创建它们，它实际上会找到以前创建的bean并跳过实例化：

Negative matches:
-----------------
...
DemoLibboApplication#libClient did not match
  - @ConditionalOnMissingBean (types: af.libbo.LibServer; SearchStrategy: all) found the following [lbServ] (OnBeanCondition)

DemoLibboApplication#libServ did not match
  - @ConditionalOnMissingBean (types: af.libbo.LibServer; SearchStrategy: all) found the following [lbServ] (OnBeanCondition)
...

Answer 2

您自己没有导入LibAutoConfiguration，是吗？

这是提示：您的主类位于自动配置类的父包中。因此，您实际上是通过组件扫描实际导入@Configuration。事实证明，当您处理该类时（通过显式导入而不是通过自动配置），尚未创建任何bean，因此它确实创建了它们。稍后处理您的应用程序类并创建这些bean。

如果您将定义移到其他位置，可能可以正常工作（因为您已经用LibConfig计算了自己），但这不是确定性的。

TL;DR确保您的自动配置代码位于单独的空间中，并且不是组件扫描的目标。我已将您的DemoLibboApplication移至demo包，并且按预期工作。

自定义springboot自动配置未检测到bean

2 个答案: