pom.xml:
spring-boot-dependencies -> spring-boot-starter-parent
spring-boot-dependencies:核心依赖在父工程,引入依赖时不需要指定版本
启动器:SpringBoot 的启动场景
XML
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
比如 spring-boot-starter-web,自动导入 web 环境所有依赖
SpringBoot 会将所有的功能场景都变成一个个的启动器
主程序:
@SpringBootApplication,标注这个类是一个 SpringBoot 的应用,启动类下的所有资源被导入
Application.class,反射加载这个类的对象
java
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
//@SpringBootApplication:标注这个类是一个SpringBoot的应用,启动类下的所有资源被导入
@SpringBootApplication
public class HelloWorldApplication {
public static void main(String[] args) {
//将SpringBoot应用启动,反射加载这个类的对象
SpringApplication.run(HelloWorldApplication.class, args);
}
}
注解:(源码)
- @SpringBootApplication -> @SpringBootConfiguration(SpringBoot 的配置)
-> @Configuration(Spring 的配置类)-> @Component(Spring 的一个组件)
- @SpringBootApplication -> @EnableAutoConfiguration(自动装配)
-> @AutoConfigurationPackage(自动装配包)
-> @Import({AutoConfigurationPackages.Registrar.class})(自动配置包注册,自动注册包)
- @SpringBootApplication -> @EnableAutoConfiguration(自动装配)
-> @Import({AutoConfigurationImportSelector.class})(自动配置导入选择器,自动导入包的核心)
获取所有的配置:
List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
获取候选的配置:
java
protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
List<String> configurations = ImportCandidates.load(AutoConfiguration.class, this.getBeanClassLoader()).getCandidates();
Assert.notEmpty(configurations, "No auto configuration classes found 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;
}
所有的自动配置类都在这
java
# ApplicationContext 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
# 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.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.MultipleConnectionPoolConfigurationsFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.NoConnectionFactoryBeanFailureAnalyzer,\
org.springframework.boot.autoconfigure.ssl.BundleContentNotWatchableFailureAnalyzer
# 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
SpringBoot 所有自动装配都是在启动的时候扫描并加载
spring.factories 所有的自动装配类都在这,但不一定生效,要判断条件是否成立
只有导入了对应的 start,就有对应的启动器,自动装配就会生效,最后配置成功
SpringBoot 在启动时,从类路径 /META-INF/spring.factories 获取指定的值
spring-boot-autoconfigure.jar 会把所有需要导入的组件,以类名的方式返回,这些组件就会被添加到容器
将这些自动配置的类导入容器,自动配置就会生效
(一个小插件 Smart Input,注释自动转换中文)