视频:面试专题-SpringBoot自动装配原理_哔哩哔哩_bilibili
当面试管问你springboot 和 普通spring 有什么区别?
您还在回答: 简化了配置 ,内置tomcat 等等 吗 ? 那只是皮毛, 最重要的还是自动化配置。一起来了解一下
第一步:
第二步:
第三步:
第四步:
public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered {
private static final String[] NO_IMPORTS = new String[0];
private static final Log logger = LogFactory.getLog(AutoConfigurationImportSelector.class);
private static final String PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE = "spring.autoconfigure.exclude";
private ConfigurableListableBeanFactory beanFactory;
private Environment environment;
private ClassLoader beanClassLoader;
private ResourceLoader resourceLoader;
public AutoConfigurationImportSelector() {
}
public String[] selectImports(AnnotationMetadata annotationMetadata) { //很重要
if (!this.isEnabled(annotationMetadata)) {
return NO_IMPORTS;
} else {
AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader.loadMetadata(this.beanClassLoader);
AnnotationAttributes attributes = this.getAttributes(annotationMetadata);
//去mata-info/spring.factories文件中 查询 EnableAutoConfiguration对应得所有类 一共110个
List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
//去除重复的配置类,若我们自己写的starter 可能存主重复的
configurations = this.removeDuplicates(configurations);
Set<String> exclusions = this.getExclusions(annotationMetadata, attributes);
this.checkExcludedClasses(configurations, exclusions);
configurations.removeAll(exclusions);
//根据maven 包导入的启动器过滤出 需要导入的配置类
configurations = this.filter(configurations, autoConfigurationMetadata);
this.fireAutoConfigurationImportEvents(configurations, exclusions);
return StringUtils.toStringArray(configurations);
}
}