“Spring Boot 自动包规则原理”的版本间的差异

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（未显示同一用户的23个中间版本）
第1行： 第1行：
 
https://www.bilibili.com/video/BV19K4y1L7MT/?p=13
 
https://www.bilibili.com/video/BV19K4y1L7MT/?p=13
  
−
=== 引导加载自动配置类 ===
+
=== 引导加载的自动配置类 ===
  
−
==== 查看 @SpringBootApplication 注解源码 ====
+
==== @SpringBootApplication ====
 
<syntaxhighlight lang="java">
 
<syntaxhighlight lang="java">
 
……
 
……
第13行： 第13行：
 
</syntaxhighlight>
 
</syntaxhighlight>
  
−
===== 查看 @SpringBootConfiguration 注解源码 =====
+
===== @SpringBootConfiguration =====
 
<syntaxhighlight lang="java">
 
<syntaxhighlight lang="java">
 
@Configuration
 
@Configuration
第20行： 第20行：
  
 
====== @Configuration ======
 
====== @Configuration ======
−
代表当前是一个配置类
+
代表当前是一个配置类，使用 @SpringBootApplication 的类也会是 Spring Boot 中的一个配置类
  
  
  
  
−
==== 查看 @ComponentScan 注解源码 ====
+
==== @ComponentScan ====
 +
 
 +
包扫描注解，指定扫描哪些包；
 +
 
  
  
−
指定扫描哪些类包，Spring 注解；
 
  
 
==== @EnableAutoConfiguration ====
 
==== @EnableAutoConfiguration ====
第39行： 第41行：
 
</syntaxhighlight>
 
</syntaxhighlight>
  
−
==== @AutoConfigurationPackage ====
+
===== @AutoConfigurationPackage =====
 
<syntaxhighlight lang="java">
 
<syntaxhighlight lang="java">
 
@Retention(RetentionPolicy.RUNTIME)
 
@Retention(RetentionPolicy.RUNTIME)
第46行： 第48行：
 
@Import(AutoConfigurationPackages.Registrar.class) //给容器中导入一个组件
 
@Import(AutoConfigurationPackages.Registrar.class) //给容器中导入一个组件
 
public @interface AutoConfigurationPackage {
 
public @interface AutoConfigurationPackage {
 +
</syntaxhighlight>比较关键的是 <code>@Import(AutoConfigurationPackages.Registrar.class)</code> 中导入的 AutoConfigurationPackages.Registrar
 +
 +
====== AutoConfigurationPackages.java ======
 +
<syntaxhighlight lang="java">
 +
……
 +
static class Registrar implements ImportBeanDefinitionRegistrar, DeterminableImports {
 +
 +
@Override
 +
public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
 +
register(registry, new PackageImports(metadata).getPackageNames().toArray(new String[0]));
 +
}
 +
 +
@Override
 +
public Set<Object> determineImports(AnnotationMetadata metadata) {
 +
return Collections.singleton(new PackageImports(metadata));
 +
}
 +
 +
}
 +
……
 +
</syntaxhighlight>利用 Registrar 向容器中导入一系列组件，<code>AnnotationMetadata metadata</code> 传入的是 @SpringBootApplication 注解标注类的注解元信息，
 +
 +
然后经由 <code>new PackageImport(metadata).getPackageName()</code> 得到 @SpringBootApplication 注解标注类的包名（比如：io.github.jihch）,
 +
 +
最终目的是将指定一个包下（@SpringBootApplication 注解标注类的包）的所有组件导入进来，
 +
 +
这就解释了为什么默认是导入 @SpringBootApplication 注解标注类的包下的所有组件
 +
 +
 +
 +
== 初始化加载自动配置类 ==
 +
https://www.bilibili.com/video/BV19K4y1L7MT?p=14
 +
 +
===== @Import(AutoConfigurationImportSelector.class) =====
 +
 +
====== AutoConfigurationImportSelector.java ======
 +
<syntaxhighlight lang="java">
 +
……
 +
        @Override
 +
public String[] selectImports(AnnotationMetadata annotationMetadata) {
 +
if (!isEnabled(annotationMetadata)) {
 +
return NO_IMPORTS;
 +
}
 +
AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(annotationMetadata);
 +
return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
 +
}
 +
……
 +
</syntaxhighlight>
 +
 +
====== 利用 <code>getAutoConfigurationEntry(annotationMetadata)</code> 往容器中批量导入一些组件： ======
 +
[[文件:利用 getAutoConfigurationEntry 导入组件.png|无|缩略图|1151x1151像素]]<syntaxhighlight lang="java">
 +
……
 +
    protected AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) {
 +
if (!isEnabled(annotationMetadata)) {
 +
return EMPTY_ENTRY;
 +
}
 +
AnnotationAttributes attributes = getAttributes(annotationMetadata);
 +
List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes);
 +
configurations = removeDuplicates(configurations);
 +
Set<String> exclusions = getExclusions(annotationMetadata, attributes);
 +
checkExcludedClasses(configurations, exclusions);
 +
configurations.removeAll(exclusions);
 +
configurations = getConfigurationClassFilter().filter(configurations);
 +
fireAutoConfigurationImportEvents(configurations, exclusions);
 +
return new AutoConfigurationEntry(configurations, exclusions);
 +
}
 +
……
 
</syntaxhighlight>
 
</syntaxhighlight>
 +
 +
====== 用 <code>List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes);</code> 获取到所有需要导入到容器中的组件： ======
 +
<syntaxhighlight lang="java">
 +
……
 +
protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
 +
List<String> configurations = SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(),
 +
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;
 +
}
 +
……
 +
</syntaxhighlight>SpringFactoriesLoader.java<syntaxhighlight lang="java">
 +
public final class SpringFactoriesLoader {
 +
……
 +
public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
 +
……
 +
public static List<String> loadFactoryNames(Class<?> factoryType, @Nullable ClassLoader classLoader) {
 +
String factoryTypeName = factoryType.getName();
 +
return loadSpringFactories(classLoader).getOrDefault(factoryTypeName, Collections.emptyList());
 +
}
 +
private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {
 +
MultiValueMap<String, String> result = cache.get(classLoader);
 +
if (result != null) {
 +
return result;
 +
}
 +
 +
try {
 +
Enumeration<URL> urls = (classLoader != null ?
 +
classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
 +
ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
 +
result = new LinkedMultiValueMap<>();
 +
while (urls.hasMoreElements()) {
 +
URL url = urls.nextElement();
 +
UrlResource resource = new UrlResource(url);
 +
Properties properties = PropertiesLoaderUtils.loadProperties(resource);
 +
for (Map.Entry<?, ?> entry : properties.entrySet()) {
 +
String factoryTypeName = ((String) entry.getKey()).trim();
 +
for (String factoryImplementationName : StringUtils.commaDelimitedListToStringArray((String) entry.getValue())) {
 +
result.add(factoryTypeName, factoryImplementationName.trim());
 +
}
 +
}
 +
}
 +
cache.put(classLoader, result);
 +
return result;
 +
}
 +
catch (IOException ex) {
 +
throw new IllegalArgumentException("Unable to load factories from location [" +
 +
FACTORIES_RESOURCE_LOCATION + "]", ex);
 +
}
 +
}
 +
……
 +
}
 +
</syntaxhighlight>
 +
 +
====== 利用工厂加载 <code>Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader)</code> 得到所有的组件； ======
 +
 +
====== 从 META-INF/spring.factories 位置来加载一个文件。 ======
 +
 +
====== 默认扫描当前系统里面所有 META-INF/spring.factories 位置的文件 ======
 +
 +
====== 比如：spring-boot-2.3.4.RELEASE.jar/META-INF/spring.factories ======
 +
<syntaxhighlight lang="properties">
 +
# PropertySource Loaders
 +
org.springframework.boot.env.PropertySourceLoader=\
 +
org.springframework.boot.env.PropertiesPropertySourceLoader,\
 +
org.springframework.boot.env.YamlPropertySourceLoader
 +
 +
……
 +
 +
# FailureAnalysisReporters
 +
org.springframework.boot.diagnostics.FailureAnalysisReporter=\
 +
org.springframework.boot.diagnostics.LoggingFailureAnalysisReporter
 +
 +
</syntaxhighlight>
 +
 +
====== 最核心的是：spring-boot-autoconfigure-2.3.4.RELEASE.jar/META-INF/spring.factories ======
 +
<syntaxhighlight lang="properties">
 +
# 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.OnBeanCondition,\
 +
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
 +
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition
 +
 +
# 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.context.ConfigurationPropertiesAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration,\
 +
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.ElasticsearchDataAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
 +
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.r2dbc.R2dbcDataAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
 +
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.ElasticsearchRestClientAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
 +
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.jersey.JerseyAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration,\
 +
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.r2dbc.R2dbcAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration,\
 +
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.security.rsocket.RSocketSecurityAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
 +
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
 +
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.ClientHttpConnectorAutoConfiguration,\
 +
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,\
 +
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration
 +
 +
# Failure analyzers
 +
org.springframework.boot.diagnostics.FailureAnalyzer=\
 +
org.springframework.boot.autoconfigure.data.redis.RedisUrlSyntaxFailureAnalyzer,\
 +
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
 +
org.springframework.boot.autoconfigure.flyway.FlywayMigrationScriptMissingFailureAnalyzer,\
 +
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
 +
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
 +
org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBeanCreationFailureAnalyzer,\
 +
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
 +
 +
</syntaxhighlight># Auto Configure 开始的除<code>org.springframework.boot.autoconfigure.EnableAutoConfiguration</code>以外的就是<code>getAutoConfigurationEntry(annotationMetadata)</code> 返回的127个组件
 +
 +
文件里面写死了 Spring Boot 一启动就要给容器中加载的所有配置类
 +
 +
虽然127个场景的所有自动配置启动的时候默认全部加载
 +
 +
但最终会按需配置，比如：<syntaxhighlight lang="java">
 +
package org.springframework.boot.autoconfigure.jdbc;
 +
 +
……
 +
 +
@Configuration(proxyBeanMethods = false)
 +
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
 +
@ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory")
 +
@EnableConfigurationProperties(DataSourceProperties.class)
 +
@Import({ DataSourcePoolMetadataProvidersConfiguration.class, DataSourceInitializationConfiguration.class })
 +
public class DataSourceAutoConfiguration {
 +
 +
@Configuration(proxyBeanMethods = false)
 +
@Conditional(EmbeddedDatabaseCondition.class)
 +
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
 +
@Import(EmbeddedDataSourceConfiguration.class)
 +
protected static class EmbeddedDatabaseConfiguration {
 +
 +
}
 +
 +
……
 +
 +
}
 +
</syntaxhighlight>都是有 <code>@Conditional</code> 注解，按照条件装备规则，最终会按需配置。
 +
 +
@12:00

2023年3月5日 (日) 09:38的最新版本

https://www.bilibili.com/video/BV19K4y1L7MT/?p=13

引导加载的自动配置类

@SpringBootApplication

……
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
@SpringBootConfiguration
@Configuration
public @interface SpringBootConfiguration {
@Configuration

代表当前是一个配置类，使用 @SpringBootApplication 的类也会是 Spring Boot 中的一个配置类



@ComponentScan

包扫描注解，指定扫描哪些包；



@EnableAutoConfiguration

……
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
……
@AutoConfigurationPackage
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import(AutoConfigurationPackages.Registrar.class) //给容器中导入一个组件
public @interface AutoConfigurationPackage {

比较关键的是 @Import(AutoConfigurationPackages.Registrar.class) 中导入的 AutoConfigurationPackages.Registrar

AutoConfigurationPackages.java
……	
	static class Registrar implements ImportBeanDefinitionRegistrar, DeterminableImports {

		@Override
		public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
			register(registry, new PackageImports(metadata).getPackageNames().toArray(new String[0]));
		}

		@Override
		public Set<Object> determineImports(AnnotationMetadata metadata) {
			return Collections.singleton(new PackageImports(metadata));
		}

	}
……

利用 Registrar 向容器中导入一系列组件，AnnotationMetadata metadata 传入的是 @SpringBootApplication 注解标注类的注解元信息，

然后经由 new PackageImport(metadata).getPackageName() 得到 @SpringBootApplication 注解标注类的包名（比如：io.github.jihch）,

最终目的是将指定一个包下（@SpringBootApplication 注解标注类的包）的所有组件导入进来，

这就解释了为什么默认是导入 @SpringBootApplication 注解标注类的包下的所有组件


初始化加载自动配置类

https://www.bilibili.com/video/BV19K4y1L7MT?p=14

@Import(AutoConfigurationImportSelector.class)
AutoConfigurationImportSelector.java
……	
        @Override
	public String[] selectImports(AnnotationMetadata annotationMetadata) {
		if (!isEnabled(annotationMetadata)) {
			return NO_IMPORTS;
		}
		AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(annotationMetadata);
		return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
	}
……
利用 getAutoConfigurationEntry(annotationMetadata) 往容器中批量导入一些组件：
利用 getAutoConfigurationEntry 导入组件.png 
……	
    protected AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) {
		if (!isEnabled(annotationMetadata)) {
			return EMPTY_ENTRY;
		}
		AnnotationAttributes attributes = getAttributes(annotationMetadata);
		List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes);
		configurations = removeDuplicates(configurations);
		Set<String> exclusions = getExclusions(annotationMetadata, attributes);
		checkExcludedClasses(configurations, exclusions);
		configurations.removeAll(exclusions);
		configurations = getConfigurationClassFilter().filter(configurations);
		fireAutoConfigurationImportEvents(configurations, exclusions);
		return new AutoConfigurationEntry(configurations, exclusions);
	}
……
用 List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes); 获取到所有需要导入到容器中的组件：
……
	protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
		List<String> configurations = SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(),
				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;
	}
……

SpringFactoriesLoader.java

public final class SpringFactoriesLoader {
	……
	public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
	……
	public static List<String> loadFactoryNames(Class<?> factoryType, @Nullable ClassLoader classLoader) {
		String factoryTypeName = factoryType.getName();
		return loadSpringFactories(classLoader).getOrDefault(factoryTypeName, Collections.emptyList());
	}
	private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {
		MultiValueMap<String, String> result = cache.get(classLoader);
		if (result != null) {
			return result;
		}

		try {
			Enumeration<URL> urls = (classLoader != null ?
					classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
					ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
			result = new LinkedMultiValueMap<>();
			while (urls.hasMoreElements()) {
				URL url = urls.nextElement();
				UrlResource resource = new UrlResource(url);
				Properties properties = PropertiesLoaderUtils.loadProperties(resource);
				for (Map.Entry<?, ?> entry : properties.entrySet()) {
					String factoryTypeName = ((String) entry.getKey()).trim();
					for (String factoryImplementationName : StringUtils.commaDelimitedListToStringArray((String) entry.getValue())) {
						result.add(factoryTypeName, factoryImplementationName.trim());
					}
				}
			}
			cache.put(classLoader, result);
			return result;
		}
		catch (IOException ex) {
			throw new IllegalArgumentException("Unable to load factories from location [" +
					FACTORIES_RESOURCE_LOCATION + "]", ex);
		}
	}
	……
}
利用工厂加载 Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) 得到所有的组件；
从 META-INF/spring.factories 位置来加载一个文件。
默认扫描当前系统里面所有 META-INF/spring.factories 位置的文件
比如：spring-boot-2.3.4.RELEASE.jar/META-INF/spring.factories
# PropertySource Loaders
org.springframework.boot.env.PropertySourceLoader=\
org.springframework.boot.env.PropertiesPropertySourceLoader,\
org.springframework.boot.env.YamlPropertySourceLoader

……

# FailureAnalysisReporters
org.springframework.boot.diagnostics.FailureAnalysisReporter=\
org.springframework.boot.diagnostics.LoggingFailureAnalysisReporter
最核心的是：spring-boot-autoconfigure-2.3.4.RELEASE.jar/META-INF/spring.factories
# 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.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

# 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.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration,\
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.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
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.r2dbc.R2dbcDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
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.ElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
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.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration,\
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.r2dbc.R2dbcAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration,\
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.security.rsocket.RSocketSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
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.ClientHttpConnectorAutoConfiguration,\
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,\
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration

# Failure analyzers
org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.boot.autoconfigure.data.redis.RedisUrlSyntaxFailureAnalyzer,\
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
org.springframework.boot.autoconfigure.flyway.FlywayMigrationScriptMissingFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBeanCreationFailureAnalyzer,\
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

# Auto Configure 开始的除org.springframework.boot.autoconfigure.EnableAutoConfiguration以外的就是getAutoConfigurationEntry(annotationMetadata) 返回的127个组件

文件里面写死了 Spring Boot 一启动就要给容器中加载的所有配置类

虽然127个场景的所有自动配置启动的时候默认全部加载

但最终会按需配置，比如：

package org.springframework.boot.autoconfigure.jdbc;

……

@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
@ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory")
@EnableConfigurationProperties(DataSourceProperties.class)
@Import({ DataSourcePoolMetadataProvidersConfiguration.class, DataSourceInitializationConfiguration.class })
public class DataSourceAutoConfiguration {

	@Configuration(proxyBeanMethods = false)
	@Conditional(EmbeddedDatabaseCondition.class)
	@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
	@Import(EmbeddedDataSourceConfiguration.class)
	protected static class EmbeddedDatabaseConfiguration {

	}

	……

}

都是有 @Conditional 注解，按照条件装备规则，最终会按需配置。

@12:00

取自“https://www.jihongchang.top/index.php?title=Spring_Boot_自动包规则原理&oldid=6270”