SpringBoot核心原理

小咪咪 2024-03-17 18:45 51阅读 0赞

## SpringBoot ##

SpringBoot的特点：

1.  依赖管理：每个SpringBoot项目都是继承自父项目，而父项目是做版本控制的，里面定义了各个常用依赖的版本，子项目只需要导入相关依赖，不需要写版本号。  
    ![在这里插入图片描述][23cfb150444b43fca443a0e90ee63d6f.png]  
    ![在这里插入图片描述][9dc7760a2d3e44bb8d51903d68b2900b.png]
2.  自动配置，SpringBoot在我们导入相关场景的依赖后，就会进行自动配置，我们只需要简单的配置就可以使用相关功能。  
    `@SpringBootApplication`这个注解是一个复合注解，由`@SpringBootConfiguration`、`@EnableAutoConfiguration`和`@ComponentScan`组成。  
    ![在这里插入图片描述][7de6afd679e3490886638171582ce313.png]  
    `@EnableAutoConfiguration`是自动配置的核心注解，因为`@SpringBootConfiguration`只是表明配置类，而`@ComponentScan`默认只扫描主程序所在的包及其子包，自动配置类都是在第三方包里，没有被扫描进来。`@EnableAutoConfiguration`的作用就是扫描自动配置类。自动配置类是通过`@Import`导入到IOC容器中。  
    ![在这里插入图片描述][d7726e0c584c41f5ad501d636ed83ea3.png]  
    通过这个方法读取所有的自动配置类，默认是从  
    `META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports`这个路径读取。

protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
        
            List<String> configurations = new ArrayList(SpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader()));
            ImportCandidates.load(AutoConfiguration.class, this.getBeanClassLoader()).forEach(configurations::add);
            Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories nor in META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports. If you are using a custom packaging, make sure that file is correct.");
            return configurations;
        }

读取到140多个自动配置类：

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.graphql.GraphQlAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.data.GraphQlReactiveQueryByExampleAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.data.GraphQlReactiveQuerydslAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.data.GraphQlQueryByExampleAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.data.GraphQlQuerydslAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.reactive.GraphQlWebFluxAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.rsocket.GraphQlRSocketAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.rsocket.RSocketGraphQlClientAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.security.GraphQlWebFluxSecurityAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.security.GraphQlWebMvcSecurityAutoConfiguration
    org.springframework.boot.autoconfigure.graphql.servlet.GraphQlWebMvcAutoConfiguration
    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

这些配置类并不是每一个都生效，而按照条件进行生效，一般都是导入相关依赖后，条件才会符合，配置的组件才会放到IOC容器里，功能才会生效。  
![在这里插入图片描述][25dd4ee94c5446c68dac482f5a0de97f.png]  
根据条件判断后最终生效的是32个。  
![在这里插入图片描述][4e63cacde7394b18bb5a214618ff1c80.png]  
每个配置类都和一个属性类进行绑定，从属性类里获取相关的配置。  
![在这里插入图片描述][385b37b1c7ea4723b560243812d18c49.png]  
yml配置文件的服务器端口配置  
![在这里插入图片描述][98f631edebb5416ba25a0460dd72f43c.png]  
对应的属性类  
![在这里插入图片描述][77abfe14f673438c9525d82961f3c8a8.png]  
总结：当程序启动的时候，会加载140多个配置类，配置类进行条件判断后，生效的从属性类里读取相关配置，创建组件放入IOC容器里。

[23cfb150444b43fca443a0e90ee63d6f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/506e83d46aa849f0a858a42e4f559273.png
[9dc7760a2d3e44bb8d51903d68b2900b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/278ee5f74a5b48cb9bdf1256f87fb60f.png
[7de6afd679e3490886638171582ce313.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/06135cbaf90a400392668a6d888dc4d9.png
[d7726e0c584c41f5ad501d636ed83ea3.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/2704f5dd49af4b25a4423020dc61e580.png
[25dd4ee94c5446c68dac482f5a0de97f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/107dd03cb00d4ded8bcf06658e62bc96.png
[4e63cacde7394b18bb5a214618ff1c80.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/a9463084f66b4584876157cac32edcc1.png
[385b37b1c7ea4723b560243812d18c49.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/b91e37f705d048ecba9abdba73106f91.png
[98f631edebb5416ba25a0460dd72f43c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/3910992c9cdd438ab95262eb1ee31d17.png
[77abfe14f673438c9525d82961f3c8a8.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/13d4c271793c43a7aa5ef59e8f071b84.png