Spring Boot | 1.6 主入口类

清疚 2022-05-24 11:05 143阅读 0赞

Spring Boot目录汇总地址：  
[https://blog.csdn.net/mengmengdastyle/article/details/80357203][https_blog.csdn.net_mengmengdastyle_article_details_80357203]

## 一、@SpringBootApplication ##

Spring Boot应用标注在某个类上说明这个类是SpringBoot的主配置类，SpringBoot就应该运行这个类的main方法来启动SpringBoot应用。

@SpringBootApplication
    public class SpringbootApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(SpringbootApplication.class, args);
        }
    }

SpringBootApplication类源码：

@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 {

从源代码中得知 @SpringBootApplication 被 @Configuration、@EnableAutoConfiguration、@ComponentScan 注解所修饰  
**（1）@SpringBootConfiguration**：标注在某个类上，表示这是一个Spring Boot的配置类；  
– @Configuration:配置类上来标注这个注解；  
配置类 —– 配置文件；配置类也是容器中的一个组件；@Component

**（2）@EnableAutoConfiguration**：启用 Spring 应用程序上下文的自动配置，试图猜测和配置您可能需要的bean。

1.  @AutoConfigurationPackage：自动配置包，中
2.  @Import(Registrar.class)：  
    Spring的底层注解@Import，给容器中导入一个组件；导入的组件由Registrar.class将主配置类（@SpringBootApplication标注的类）的所在包及下面所有子包里面的所有组件扫描到Spring容器；
3.  @Import(\{AutoConfigurationImportSelector.class\})：  
    将所有需要导入的组件以全类名的方式返回；这些组件就会被添加到容器中；  
    获取类路径下spring.factories下key为EnableAutoConfiguration全限定名对应值

SpringFactoriesLoader.loadFactoryNames(EnableAutoConfiguration.class,classLoader)；

其结果为：

# Auto Configure 
    org.springframework.boot.autoconfigure.EnableAutoConfiguration=\  
    org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\  
    org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\  
    org.springframework.boot.autoconfigure.MessageSourceAutoConfiguration,\  
    org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration,\  
    org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\  
    org.springframework.boot.autoconfigure.cloud.CloudAutoConfiguration,\  
    org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\  
    org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\  
    org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\  
    org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\  
    org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\  
    org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\  
    org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\  
    org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\  
    org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\  
    org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\  
    org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\  
    org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\  
    org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\  
    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.hornetq.HornetQAutoConfiguration,\  
    org.springframework.boot.autoconfigure.jta.JtaAutoConfiguration,\  
    org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchAutoConfiguration,\  
    org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchDataAutoConfiguration,\  
    org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\  
    org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\  
    org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\  
    org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mobile.DeviceResolverAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mobile.DeviceDelegatingViewResolverAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mobile.SitePreferenceAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mongo.MongoDataAutoConfiguration,\  
    org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\  
    org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\  
    org.springframework.boot.autoconfigure.reactor.ReactorAutoConfiguration,\  
    org.springframework.boot.autoconfigure.redis.RedisAutoConfiguration,\  
    org.springframework.boot.autoconfigure.security.SecurityAutoConfiguration,\  
    org.springframework.boot.autoconfigure.security.FallbackWebSecurityAutoConfiguration,\  
    org.springframework.boot.autoconfigure.social.SocialWebAutoConfiguration,\  
    org.springframework.boot.autoconfigure.social.FacebookAutoConfiguration,\  
    org.springframework.boot.autoconfigure.social.LinkedInAutoConfiguration,\  
    org.springframework.boot.autoconfigure.social.TwitterAutoConfiguration,\  
    org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\  
    org.springframework.boot.autoconfigure.velocity.VelocityAutoConfiguration,\  
    org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.GzipFilterAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.HttpEncodingAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration,\  
    org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration,\  
    org.springframework.boot.autoconfigure.websocket.WebSocketAutoConfiguration

**（3）@ComponentScan**：自动扫描当前包及子包下所有类。

[https_blog.csdn.net_mengmengdastyle_article_details_80357203]: https://blog.csdn.net/mengmengdastyle/article/details/80357203