Springboot中enable注解

　　这句话能够做为理解springboot自动注入的原理的钥匙：ImportSelector接口的selectImports返回的数组（类的全类名）都会被归入到spring容器中.

　　至于spring怎么根据类名建立bean的就不用管了。博文地址https://www.jianshu.com/p/464d04c36fb1

public class AutoConfigurationImportSelector
		implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware,
		BeanFactoryAware, EnvironmentAware, Ordered  //看这个类实现的接口多复杂

@Override
	public String[] selectImports(AnnotationMetadata annotationMetadata) {
		if (!isEnabled(annotationMetadata)) {
			return NO_IMPORTS;
		}
		AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader
				.loadMetadata(this.beanClassLoader);
		AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(
				autoConfigurationMetadata, annotationMetadata);
		return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
	}

　　这个方法就是导入了自动配置的文件的字符串。