大三上寒假生活打卡020

@SpringBootConfiguration：SpringBoot的配置

@Configuration： spring配置类
@Component：说明这也是一个spring的组件

@EnableAutoConfiguration：自动配置

@AutoConfigurationPackage：自动配置包
    @Import({Registrar.class})：导入了选择器
@Import({AutoConfigurationImportSelector.class})：自动配置选择器
    List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
    //获取所有的配置

protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
        List<String> configurations = SpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader());
        Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you are using a custom packaging, make sure that file is correct.");
        return configurations;
    }