Spring源码-ConfigurationClassPostProcessor类解析spring相关注解

ConfigurationClassPostProcessor类的作用

此类是一个后置处理器的类，主要功能是参与BeanFactory的建造，主要功能如下
1、解析加了@Configuration的配置类
2、解析@ComponentScan扫描的包
3、解析@ComponentScans扫描的包
4、解析@Import注解

该类在springboot中的作用

该类是springboot的自动装配的入口类，通过该类解析
@SpringBootApplication注解上的@EnableAutoConfiguration，

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {@Filter(type = FilterType.CUSTOM,classes = {TypeExcludeFilter.class}
), @Filter(type = FilterType.CUSTOM,classes = {AutoConfigurationExcludeFilter.class}
)}
)
public @interface SpringBootApplication {@AliasFor(annotation = EnableAutoConfiguration.class)Class<?>[] exclude() default {};@AliasFor(annotation = EnableAutoConfiguration.class)String[] excludeName() default {};@AliasFor(annotation = ComponentScan.class,attribute = "basePackages")String[] scanBasePackages() default {};@AliasFor(annotation = ComponentScan.class,attribute = "basePackageClasses")Class<?>[] scanBasePackageClasses() default {};@AliasFor(annotation = ComponentScan.class,attribute = "nameGenerator")Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;@AliasFor(annotation = Configuration.class)boolean proxyBeanMethods() default true;
}

这个注解上有个@Import({AutoConfigurationImportSelector.class})

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import({AutoConfigurationImportSelector.class})
public @interface EnableAutoConfiguration {String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";Class<?>[] exclude() default {};String[] excludeName() default {};
}

最终执行到这里的时候，会加载spring.factories文件，会有EnableAutoConfiguration这个key映射的哪些类路径，只有加载这些才会完成自动装配，具体怎么执行到这里的加载步骤，后续给出。

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\
org.springframework.boot.autoconfigure.cloud.CloudAutoConfiguration,\
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.jest.JestAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.reactor.core.ReactorCoreAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration

在这里插入图片描述

	protected Class<?> getSpringFactoriesLoaderFactoryClass() {return EnableAutoConfiguration.class;}

在这里插入图片描述

# Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.autoconfigure.BackgroundPreinitializer# Auto Configuration Import Listeners
org.springframework.boot.autoconfigure.AutoConfigurationImportListener=\
org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoConfigurationImportListener# Auto Configuration Import Filters
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnClassCondition# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\
org.springframework.boot.autoconfigure.cloud.CloudAutoConfiguration,\
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.jest.JestAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.reactor.core.ReactorCoreAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration# Failure analyzers
org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
org.springframework.boot.autoconfigure.session.NonUniqueSessionRepositoryFailureAnalyzer# Template availability providers
org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider=\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.mustache.MustacheTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.web.servlet.JspTemplateAvailabilityProvider

/*** DeferredImportSelector是ImportSelect的子接口，该接口会在所有的@Configuration配置类处理完成后运行* 当选择器和@Conditional条件注解一起使用时是特别有用的，此接口还可以和接口Ordered或者@Ordered一起使用，定义多个选择器的优先级** A variation of {@link ImportSelector} that runs after all {@code @Configuration} beans* have been processed. This type of selector can be particularly useful when the selected* imports are {@code @Conditional}.** <p>Implementations can also extend the {@link org.springframework.core.Ordered}* interface or use the {@link org.springframework.core.annotation.Order} annotation to* indicate a precedence against other {@link DeferredImportSelector DeferredImportSelectors}.** <p>Implementations may also provide an {@link #getImportGroup() import group} which* can provide additional sorting and filtering logic across different selectors.** @author Phillip Webb* @author Stephane Nicoll* @since 4.0*/
public interface DeferredImportSelector extends ImportSelector {/*** 返回制定一个的导入结果集** Return a specific import group.* <p>The default implementations return {@code null} for no grouping required.* @return the import group class, or {@code null} if none* @since 5.0*/@Nullabledefault Class<? extends Group> getImportGroup() {return null;}/*** 用于从不同的DeferredImportSelector中获取需要导入类的结果集** Interface used to group results from different import selectors.* @since 5.0*/interface Group {/*** 根据AnnotationMetadata注解元数据获取@Configuration配置的@Import注解导入的DeferredImportSelector选择器** Process the {@link AnnotationMetadata} of the importing @{@link Configuration}* class using the specified {@link DeferredImportSelector}.*/void process(AnnotationMetadata metadata, DeferredImportSelector selector);/*** 返回类应该导入的Entry** Return the {@link Entry entries} of which class(es) should be imported* for this group.*/Iterable<Entry> selectImports();/*** 存储要导入类的全限定名及AnnotationMetadata注解元数据** An entry that holds the {@link AnnotationMetadata} of the importing* {@link Configuration} class and the class name to import.*/class Entry {private final AnnotationMetadata metadata;private final String importClassName;public Entry(AnnotationMetadata metadata, String importClassName) {this.metadata = metadata;this.importClassName = importClassName;}/*** 返回要引入的Configuration类的AnnotationMetaData注解元数据** Return the {@link AnnotationMetadata} of the importing* {@link Configuration} class.*/public AnnotationMetadata getMetadata() {return this.metadata;}/*** 返回要导入类的全限定名** Return the fully qualified name of the class to import.*/public String getImportClassName() {return this.importClassName;}@Overridepublic boolean equals(@Nullable Object other) {if (this == other) {return true;}if (other == null || getClass() != other.getClass()) {return false;}Entry entry = (Entry) other;return (this.metadata.equals(entry.metadata) && this.importClassName.equals(entry.importClassName));}@Overridepublic int hashCode() {return (this.metadata.hashCode() * 31 + this.importClassName.hashCode());}@Overridepublic String toString() {return this.importClassName;}}}}

/*** 此接口是spring中导入外部配置的核心接口，根据给定的条件（通常是一个或多个注解属性）判断要导入哪个配置类* 如果该接口的实现类同时实现了一些Aware接口，那么在调用selectImports方法之前先调用上述接口中的回调方法* 如果需要在所有的@Configuration处理完再导入，可以实现DeferredImportSelector接口*** Interface to be implemented by types that determine which @{@link Configuration}* class(es) should be imported based on a given selection criteria, usually one or* more annotation attributes.** <p>An {@link ImportSelector} may implement any of the following* {@link org.springframework.beans.factory.Aware Aware} interfaces,* and their respective methods will be called prior to {@link #selectImports}:* <ul>* <li>{@link org.springframework.context.EnvironmentAware EnvironmentAware}</li>* <li>{@link org.springframework.beans.factory.BeanFactoryAware BeanFactoryAware}</li>* <li>{@link org.springframework.beans.factory.BeanClassLoaderAware BeanClassLoaderAware}</li>* <li>{@link org.springframework.context.ResourceLoaderAware ResourceLoaderAware}</li>* </ul>** <p>Alternatively, the class may provide a single constructor with one or more of* the following supported parameter types:* <ul>* <li>{@link org.springframework.core.env.Environment Environment}</li>* <li>{@link org.springframework.beans.factory.BeanFactory BeanFactory}</li>* <li>{@link java.lang.ClassLoader ClassLoader}</li>* <li>{@link org.springframework.core.io.ResourceLoader ResourceLoader}</li>* </ul>** <p>{@code ImportSelector} implementations are usually processed in the same way* as regular {@code @Import} annotations, however, it is also possible to defer* selection of imports until all {@code @Configuration} classes have been processed* (see {@link DeferredImportSelector} for details).** @author Chris Beams* @author Juergen Hoeller* @since 3.1* @see DeferredImportSelector* @see Import* @see ImportBeanDefinitionRegistrar* @see Configuration*/
public interface ImportSelector {/*** Select and return the names of which class(es) should be imported based on* the {@link AnnotationMetadata} of the importing @{@link Configuration} class.* @return the class names, or an empty array if none*/String[] selectImports(AnnotationMetadata importingClassMetadata);/*** Return a predicate for excluding classes from the import candidates, to be* transitively applied to all classes found through this selector's imports.* <p>If this predicate returns {@code true} for a given fully-qualified* class name, said class will not be considered as an imported configuration* class, bypassing class file loading as well as metadata introspection.* @return the filter predicate for fully-qualified candidate class names* of transitively imported configuration classes, or {@code null} if none* @since 5.2.4*/@Nullabledefault Predicate<String> getExclusionFilter() {return null;}}


/*** Indicates one or more <em>component classes</em> to import &mdash; typically* {@link Configuration @Configuration} classes.** <p>Provides functionality equivalent to the {@code <import/>} element in Spring XML.* Allows for importing {@code @Configuration} classes, {@link ImportSelector} and* {@link ImportBeanDefinitionRegistrar} implementations, as well as regular component* classes (as of 4.2; analogous to {@link AnnotationConfigApplicationContext#register}).** <p>{@code @Bean} definitions declared in imported {@code @Configuration} classes should be* accessed by using {@link org.springframework.beans.factory.annotation.Autowired @Autowired}* injection. Either the bean itself can be autowired, or the configuration class instance* declaring the bean can be autowired. The latter approach allows for explicit, IDE-friendly* navigation between {@code @Configuration} class methods.** <p>May be declared at the class level or as a meta-annotation.** <p>If XML or other non-{@code @Configuration} bean definition resources need to be* imported, use the {@link ImportResource @ImportResource} annotation instead.** @author Chris Beams* @author Juergen Hoeller* @since 3.0* @see Configuration* @see ImportSelector* @see ImportBeanDefinitionRegistrar* @see ImportResource*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Import {/*** {@link Configuration @Configuration}, {@link ImportSelector},* {@link ImportBeanDefinitionRegistrar}, or regular component classes to import.*/Class<?>[] value();}

SpringBoot项目有个@SpringBootApplication注解

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {。。。。。。}

有个@EnableAutoConfiguration

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";/*** Exclude specific auto-configuration classes such that they will never be applied.* @return the classes to exclude*/Class<?>[] exclude() default {};/*** Exclude specific auto-configuration class names such that they will never be* applied.* @return the class names to exclude* @since 1.3.0*/String[] excludeName() default {};}

上面有个注解@Import(AutoConfigurationImportSelector.class)

public class AutoConfigurationImportSelectorimplements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware,BeanFactoryAware, EnvironmentAware, Ordered {。。。。。。}

AutoConfigurationImportSelector就存放在importCandidates，他实现DeferredImportSelector就会在

// 将选择器添加到deferredImportSelectorHandler实例中，预留到所有的配置类加载完成后统一处理自动化配置类  延迟处理
this.deferredImportSelectorHandler.handle(configClass, (DeferredImportSelector) selector);

在这里插入图片描述

		/*** Handle the specified {@link DeferredImportSelector}. If deferred import* selectors are being collected, this registers this instance to the list. If* they are being processed, the {@link DeferredImportSelector} is also processed* immediately according to its {@link DeferredImportSelector.Group}.* @param configClass the source configuration class* @param importSelector the selector to handle*/public void handle(ConfigurationClass configClass, DeferredImportSelector importSelector) {DeferredImportSelectorHolder holder = new DeferredImportSelectorHolder(configClass, importSelector);if (this.deferredImportSelectors == null) {DeferredImportSelectorGroupingHandler handler = new DeferredImportSelectorGroupingHandler();handler.register(holder);handler.processGroupImports();}else {this.deferredImportSelectors.add(holder);}}

添加到deferredImportSelectors集合中
ConfigurationClassParser类的

public void parse(Set<BeanDefinitionHolder> configCandidates) {// 循环遍历configCandidatesfor (BeanDefinitionHolder holder : configCandidates) {// 获取BeanDefinitionBeanDefinition bd = holder.getBeanDefinition();// 根据BeanDefinition类型的不同，调用parse不同的重载方法，实际上最终都是调用processConfigurationClass()方法try {// 注解类型if (bd instanceof AnnotatedBeanDefinition) {parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName());}// 有class对象的else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) bd).hasBeanClass()) {parse(((AbstractBeanDefinition) bd).getBeanClass(), holder.getBeanName());}else {parse(bd.getBeanClassName(), holder.getBeanName());}}catch (BeanDefinitionStoreException ex) {throw ex;}catch (Throwable ex) {throw new BeanDefinitionStoreException("Failed to parse configuration class [" + bd.getBeanClassName() + "]", ex);}}// 执行找到的DeferredImportSelector// DeferredImportSelector是ImportSelector的一个子类// ImportSelector被设计成和@Import注解同样的效果，但是实现了ImportSelector的类可以条件性的决定导入某些配置// DeferredImportSelector的设计魔都是在所有其他的配置类被处理后才进行处理this.deferredImportSelectorHandler.process();}

this.deferredImportSelectorHandler.process();执行:

		public void process() {// 此处获取@Import注解导入器List<DeferredImportSelectorHolder> deferredImports = this.deferredImportSelectors;this.deferredImportSelectors = null;try {if (deferredImports != null) {DeferredImportSelectorGroupingHandler handler = new DeferredImportSelectorGroupingHandler();deferredImports.sort(DEFERRED_IMPORT_COMPARATOR);deferredImports.forEach(handler::register);// 核心处理类，此处完成自动配置功能handler.processGroupImports();}}finally {this.deferredImportSelectors = new ArrayList<>();}}

// 核心处理类，此处完成自动配置功能
handler.processGroupImports();

		public void processGroupImports() {for (DeferredImportSelectorGrouping grouping : this.groupings.values()) {Predicate<String> exclusionFilter = grouping.getCandidateFilter();// getImports方法是读取自动化配置类的核心入口，  // 遍历分组， grouping.getImports()是关键grouping.getImports().forEach(entry -> {ConfigurationClass configurationClass = this.configurationClasses.get(entry.getMetadata());try { // 同ImportSelector的实现类一样，最终也是调用 processImports(...) 处理导入// 配置类中可能会包含@Import注解引入的类，通过此方法将引入的类注入 // 注意 entry.getImportClassName()，这一次调用 processImports(...) 的参processImports(configurationClass, asSourceClass(configurationClass, exclusionFilter), // 数是ImportSelector引入的类Collections.singleton(asSourceClass(entry.getImportClassName(), exclusionFilter)),exclusionFilter, false);}catch (BeanDefinitionStoreException ex) {throw ex;}catch (Throwable ex) {throw new BeanDefinitionStoreException("Failed to process import candidates for configuration class [" +configurationClass.getMetadata().getClassName() + "]", ex);}});}}

grouping.getImports()

		/*** Return the imports defined by the group.* @return each import with its associated configuration class*/public Iterable<Group.Entry> getImports() {for (DeferredImportSelectorHolder deferredImport : this.deferredImports) {// 核心方法，在springboot中此方法会去SpringFactoriesLoader类中加载自动化配置类this.group.process(deferredImport.getConfigurationClass().getMetadata(),deferredImport.getImportSelector());}// 获取已经取得的配置类return this.group.selectImports();}