SpringBoot自动装配

自动装配流程

flowchart LR
SpringBootApplication --> EnableAutoConfiguration --> AutoConfigurationImportSelector --> selectImports

public String[] selectImports(AnnotationMetadata annotationMetadata) {
  			// 判断自动装配开关是否打开
        if (!this.isEnabled(annotationMetadata)) {
            return NO_IMPORTS;
        } else {
          // 加载自动配置类
            AutoConfigurationImportSelector.AutoConfigurationEntry autoConfigurationEntry = this.getAutoConfigurationEntry(annotationMetadata);
				return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
    }

自动装配的具体实现

protected AutoConfigurationImportSelector.AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) {
       if (!this.isEnabled(annotationMetadata)) {
           return EMPTY_ENTRY;
       } else {
         // 获取EnableAutoConfiguration注解中的 exclude 和 excludeName
           AnnotationAttributes attributes = this.getAttributes(annotationMetadata);
         // 获取需要自动装配的所有配置类，读取META-INF/spring.factories
           List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
         // 移除需要排除的配置类
           configurations = this.removeDuplicates(configurations);
           Set<String> exclusions = this.getExclusions(annotationMetadata, attributes);
           this.checkExcludedClasses(configurations, exclusions);
         // 移除需要排除的配置类
           configurations.removeAll(exclusions);
         // 根据@ConditionalOnXXX过滤配置类
           configurations = this.getConfigurationClassFilter().filter(configurations);
           this.fireAutoConfigurationImportEvents(configurations, exclusions);
           return new AutoConfigurationImportSelector.AutoConfigurationEntry(configurations, exclusions);
       }
   }