Springboot自动装配:三个注解、Selector、spring.factories文件、@ConditionalOnProperty注解

这篇具有很好参考价值的文章主要介绍了Springboot自动装配:三个注解、Selector、spring.factories文件、@ConditionalOnProperty注解。希望对大家有所帮助。如果存在错误或未考虑完全的地方,请大家不吝赐教,您也可以点击"举报违法"按钮提交疑问。

借鉴:
这个链接是包含run方法进来debug看整个过程的,建议先看:https://www.cnblogs.com/starsray/p/15580915.html
https://blog.csdn.net/fengxiandada/article/details/130080828

Springboot自动装配

1.创建springboot应用
如何创建一个spring boot应用?这就很简单了,可以使用idea自带的spring initializr帮助我们选择相应的场景启动器也就是starter,快速创建应用,也可以访问spring官方网站来创建应用。

2.自动装配原理
Spring Boot的自动装配主要依靠注解和相关实现来完成,这里从注解开始进行逐层分析,主程序注解@SpringBootApplication,这个注解是一个合成注解,包含以下三个注解:

@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan

@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 {
	************************************省略
}

@SpringBootConfiguration

通过源码可以看到这个注解内部只包含一个@Configuration注解,来标注这是这个配置类。

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Configuration
@Indexed
public @interface SpringBootConfiguration {
    @AliasFor(
        annotation = Configuration.class
    )
    boolean proxyBeanMethods() default true;
}

@ComponentScan

这个注解主要进行标注一个Spring Boot应用的包扫描范围,默认扫描组件包含主程序所在的同一级别或者子包所在的范围。
包路径默认规则由AutoConfigurationExcludeFilter类来实现。


@EnableAutoConfiguration

Spring Boot自动配置的功能主要由这个注解来实现,实现自动加载不同的场景依赖,查看源码

@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 {};
}


这里包含了@AutoConfigurationPackage注解和导入了一个类,这里属于@Import注解的高级用法,先查看@AutoConfigurationPackage这个注解的源码

@AutoConfigurationPackage

注解@Import导入了一个类通过一个Registrar来对包进行自动配置,查看Registrar源码内容

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import({Registrar.class})
public @interface AutoConfigurationPackage {
    String[] basePackages() default {};

    Class<?>[] basePackageClasses() default {};
}

Registrar.java

static class Registrar implements ImportBeanDefinitionRegistrar, DeterminableImports {
        Registrar() {
        }

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

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

也就是说当SpringBoot应用启动时默认会将启动类所在的package作为自动配置的package,来扫描加载应用内部的组件,如果包名需要自定义这时就可以使用@ComponentScan注解来指定。

除了自动包管理之外,Spring Boot应用在启动时还有默认组件需要进行加载,这里主要依靠@EnableAutoConfiguration注解中导入的AutoConfigurationImportSelector类来完成。查看主要源码流程。

AutoConfigurationImportSelector.java

通过selectImports方法来返回需要加载的自动配置类组件数组。
通过getAutoConfigurationEntry方法获取需要被自动配置的entry信息

/**
 * @author Phillip Webb
 * @author Andy Wilkinson
 */
public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware,
		ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered {

	private static final AutoConfigurationEntry EMPTY_ENTRY = new AutoConfigurationEntry();

	private static final String[] NO_IMPORTS = {};

	private static final Log logger = LogFactory.getLog(AutoConfigurationImportSelector.class);

	private static final String PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE = "spring.autoconfigure.exclude";

	*********************************************省略
	
	//重点:通过selectImports方法来返回需要加载的自动配置类组件数组。
	@Override
	public String[] selectImports(AnnotationMetadata annotationMetadata) {
		if (!isEnabled(annotationMetadata)) {
			return NO_IMPORTS;
		}
		AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(annotationMetadata);
		return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
	}

	//重点:通过getAutoConfigurationEntry方法获取需要被自动配置的entry信息
	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);
	}
	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

获取候选加载的组件信息,通过代码追踪可以看到,在应用启动过程中,Spring Boot会默认加载classpath下META-INF/spring.factories中所配置的entry信息。
通过loadFactoryNames方法来加载自动配置类信息
此处可以看到从META-INF/spring.factories文件中获取需要被加载的配置信息



public final class SpringFactoriesLoader {

	
		public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
		
		
		private static final Log logger = LogFactory.getLog(SpringFactoriesLoader.class);
		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);
		}
	}
	

其中Spring Boot starter所包含的127个场景启动器都被写入在spring.factories中,这些就是需要在项目启动时被加载的entry信息,包括常见的AOP组件,Spring MVC组件,如果是web应用在项目启动时会使用默认配置被加载到Spring容器中。但是这么多组件都会被加载吗?并不是,这里只是列举出来需要被自动配置的组件信息,具体什么时候加载,Spring Boot会按需加载。这里以AOP和RabbitMQ的自配配置为例。

例子:AOP自动配置:查看源码AopAutoConfiguration

AopAutoConfiguration加载流程可以看:https://blog.csdn.net/jy02268879/article/details/88370380

这里说明了只有当配置文件中注解@ConditionalOnProperty指定了属性spring.aop.auto为true时,并且不指定也默认为true,从这里也可以看出AOP配置组件是默认生效的。

@ConditionalOnProperty:简单来讲,一般是在配置类上或者是@Bean修饰的方法上,添加此注解表示一个类是否要被Spring上下文加载,若满足条件则加载,若不满足条件则不加载。

我们在application.properties中配置的各种配置,添加配置之后即生效,就是这么控制的。
prefix:配置文件中的前缀。
name:配置的名字。
havingValue:它的值与配置文件的值对比,当两个值相同,类会被加载到spring的IOC容器中。
matchIfMissing:缺少该配置时是否可以加载,如果为true,没有该配置属性时也会正常加载,反之则不会生效。


@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(prefix = "spring.aop", name = "auto", havingValue = "true", matchIfMissing = true)
public class AopAutoConfiguration {

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(Advice.class)
	static class AspectJAutoProxyingConfiguration {

		@Configuration(proxyBeanMethods = false)
		@EnableAspectJAutoProxy(proxyTargetClass = false)
		@ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "false",
				matchIfMissing = false)
		static class JdkDynamicAutoProxyConfiguration {

		}

		@Configuration(proxyBeanMethods = false)
		@EnableAspectJAutoProxy(proxyTargetClass = true)
		@ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "true",
				matchIfMissing = true)
		static class CglibAutoProxyConfiguration {

		}

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnMissingClass("org.aspectj.weaver.Advice")
	@ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "true",
			matchIfMissing = true)
	static class ClassProxyingConfiguration {

		ClassProxyingConfiguration(BeanFactory beanFactory) {
			if (beanFactory instanceof BeanDefinitionRegistry) {
				BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
				AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry);
				AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
			}
		}

	}

}

META-INF/spring.factories文件: 下面包含org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,AOP的加载类(组件)

# 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

# Environment Post Processors
org.springframework.boot.env.EnvironmentPostProcessor=\
org.springframework.boot.autoconfigure.integration.IntegrationPropertiesEnvironmentPostProcessor

# 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.Neo4jReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
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.neo4j.Neo4jAutoConfiguration,\
org.springframework.boot.autoconfigure.netty.NettyAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
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.sql.init.SqlInitializationAutoConfiguration,\
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.ReactiveMultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebSessionIdResolverAutoConfiguration,\
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.jooq.NoDslContextBeanFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.MissingR2dbcPoolDependencyFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.MultipleConnectionPoolConfigurationsFailureAnalzyer,\
org.springframework.boot.autoconfigure.r2dbc.NoConnectionFactoryBeanFailureAnalyzer,\
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

# DataSource initializer detectors
org.springframework.boot.sql.init.dependency.DatabaseInitializerDetector=\
org.springframework.boot.autoconfigure.flyway.FlywayMigrationInitializerDatabaseInitializerDetector

# Depends on database initialization detectors
org.springframework.boot.sql.init.dependency.DependsOnDatabaseInitializationDetector=\
org.springframework.boot.autoconfigure.batch.JobRepositoryDependsOnDatabaseInitializationDetector,\
org.springframework.boot.autoconfigure.quartz.SchedulerDependsOnDatabaseInitializationDetector,\
org.springframework.boot.autoconfigure.session.JdbcIndexedSessionRepositoryDependsOnDatabaseInitializationDetector

3.流程分析(面试回答)

1.@SpringBootApplication标明启动主程序,可以使用exclude属性来排除需要进行自动装配的组件,使用scanBasePackages来指明需要扫描的包。
2.@SpringBootApplication --> @EnableAutoConfiguration -->@AutoConfigurationPackage进行自动包管理,加载应用内相关组件。
3.通过流程,AutoConfigurationImportSelector类的方法selectImports --> 方法getAutoConfigurationEntry --> 方法getCandidateConfigurations,再到SpringFactoriesLoader类的方法loadFactoryNames --> 方法loadSpringFactories
,再到文件META-INF/spring.factories来获取需要被加载的entry信息(组件),然后根据组件的自动配置类中的ConditionalOnProperty注解来判断配置是否生效,按需加载

Spring Boot的自动装配原理借鉴了Java SPI机制,简单总结就是,自动管理,按需加载。文章来源地址https://www.toymoban.com/news/detail-815612.html

到了这里,关于Springboot自动装配:三个注解、Selector、spring.factories文件、@ConditionalOnProperty注解的文章就介绍完了。如果您还想了解更多内容,请在右上角搜索TOY模板网以前的文章或继续浏览下面的相关文章,希望大家以后多多支持TOY模板网!

本文来自互联网用户投稿,该文观点仅代表作者本人,不代表本站立场。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如若转载,请注明出处: 如若内容造成侵权/违法违规/事实不符,请点击违法举报进行投诉反馈,一经查实,立即删除!

领支付宝红包 赞助服务器费用

相关文章

  • 拆解Spring boot:Springboot为什么如此丝滑而简单?源码剖析解读自动装配

    🎉🎉欢迎光临,终于等到你啦🎉🎉 🏅我是苏泽,一位对技术充满热情的探索者和分享者。🚀🚀 🌟持续更新的专栏 《Spring 狂野之旅:从入门到入魔》 🚀 本专栏带你从Spring入门到入魔   这是苏泽的个人主页可以看到我其他的内容哦👇👇 努力的苏泽 http://suzee.blog.csdn

    2024年03月23日
    浏览(42)
  • Spring使用注解进行对象装配(DI)

    通过五大类注解可以更便捷的将对象存储到 Spring 中,同样也可以使用注解将已经储存的对象取出来,直接赋值到注解所在类的一个属性中,这一个过程也叫做对象的装配或者叫对象的注入,即 DI。 获取 Bean 对象也叫做对象装配,就是把对象取出来放到某个类中,有时候也叫

    2024年02月15日
    浏览(37)
  • SpringBoot3.0新特性:1、spring.factories文件废弃,自动配置包位置变化 2、Spring Native 快速体验 3、jakata api迁移 3、三方库的支持

    有自己写过starter包的友友们一定知道,一定用/META-INF/spring.factories文件定义发现自动配置,但是在springboot 2.7,这个文件就被弃用了,在springboot 3.0 就被彻底移除了。 比如之前定义的/META-INF/spring.factories文件: 而现在 这个/META-INF/spring.factories并不是不存在了,只是在3.0之后 外

    2024年02月10日
    浏览(43)
  • spring boot自动装配及自动装配条件判断

    第一步需要在pom.xml文件指定需要导入的坐标 要是没有自动提示需要检查maven有没有 实现代码 执行代码示例

    2024年02月20日
    浏览(36)
  • @SpringBootApplication注解的理解——如何排除自动装配 & 分布式情况下如何自动加载 & nacos是怎么被发现的

    spring作为主流的 Java Web 开发的开源框架,是Java 世界最为成功的框架,持续不断深入认识spring框架是Java程序员不变的追求。 本篇博客介绍SpringBootApplicant注解的自动加载相关内容 其他相关的Spring博客文章列表如下: Spring基础(核心容器)——从配置文件到注解开发 创建对象

    2024年02月07日
    浏览(41)
  • spring自动装配原理

    为了搞明白自动装配原理,需要知道spring容器管理bean的生命周期 分为四步: 1、实例化 读取spring配置文件 通过反射进行bean的实例化(eg:通过BeanFactory实例化) 2、属性赋值 解析 自动装配 (byName、byType、constractor、default)DI的体现 循环依赖 3、初始化 调用XXXAware回调方法

    2024年02月02日
    浏览(36)
  • Spring Boot自动装配

    自动装配是 Spring Boot 最核心的功能之一,第三方可以基于这个特性非常方便的和 Spring 做整合,实现自己的 Starter,做到开箱即用。 Java 早期并不支持注解,所以那会儿 Spring 只能通过 xml 的形式来配置。早期项目里要引入一个功能模块,首先我们要引入 SDK,然后在 xml 里配置

    2024年01月23日
    浏览(42)
  • Spring Boot 自动装配原理

    Java面试题目录 Spring Boot自动装配原理   Spring Boot启动类上的 @SpringBootApplication 注解中包含 @EnableAutoConfiguration 注解,表示开启自动装配。在@EnableAutoConfiguration注解中使用@Import注解引入 AutoConfigurationImportSelector 组件,此类中通过 SpringFactoriesLoader.loadFactoryNames() 方法来扫描所有

    2024年01月25日
    浏览(40)
  • SpringBoot源码-自动装配

      springboot的核心注解@SpringBootApplication 接着看 @SpringBootApplication 注解 截图: 代码:  接着看红框的注解 @EnableAutoConfiguration 截图: 代码:  接着看红框的 AutoConfigurationImportSelector.class 这个类 截图: 接着看接口 DeferredImportSelector 的实现 截图: 在这个DeferredImportSelector类中,

    2024年02月08日
    浏览(48)
  • springboot自动装配大概原理

    自动装配 : pom.xml spring-boot-dependence:核心都依赖在父类工程中! 我们在写入或者引入springboot依赖的时候,不需要指定版,因为有这些仓库的版本 启动器:------spring boot的启动场景 比如spring-boot-starter-web,他就会帮我们导入web环境苏需要的依赖。 springboot会将所有的功能场景

    2023年04月25日
    浏览(35)

觉得文章有用就打赏一下文章作者

支付宝扫一扫打赏

博客赞助

微信扫一扫打赏

请作者喝杯咖啡吧~博客赞助

支付宝扫一扫领取红包,优惠每天领

二维码1

领取红包

二维码2

领红包