启动类

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

run()

看注释default settings和the running {@link ApplicationContext}

SpringBootApplication.java

/** * Indicates a {@link Configuration configuration} class that declares one or more * {@link Bean @Bean} methods and also triggers {@link EnableAutoConfiguration * auto-configuration}, {@link ComponentScan component scanning}, and * {@link ConfigurationPropertiesScan configuration properties scanning}. This is a * convenience annotation that is equivalent to declaring {@code @Configuration}, * {@code @EnableAutoConfiguration}, {@code @ComponentScan}. * * @author Phillip Webb * @author Stephane Nicoll * @author Andy Wilkinson * @since 1.2.0 */ @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 { /** * Exclude specific auto-configuration classes such that they will never be applied. * @return the classes to exclude */ @AliasFor(annotation = EnableAutoConfiguration.class) Class<?>[] exclude() default {}; /** * Exclude specific auto-configuration class names such that they will never be * applied. * @return the class names to exclude * @since 1.3.0 */ @AliasFor(annotation = EnableAutoConfiguration.class) String[] excludeName() default {}; /** * Base packages to scan for annotated components. Use {@link #scanBasePackageClasses} * for a type-safe alternative to String-based package names. * <p> * <strong>Note:</strong> this setting is an alias for * {@link ComponentScan @ComponentScan} only. It has no effect on {@code @Entity} * scanning or Spring Data {@link Repository} scanning. For those you should add * {@link org.springframework.boot.autoconfigure.domain.EntityScan @EntityScan} and * {@code @Enable...Repositories} annotations. * @return base packages to scan * @since 1.3.0 */ @AliasFor(annotation = ComponentScan.class, attribute = "basePackages") String[] scanBasePackages() default {}; /** * Type-safe alternative to {@link #scanBasePackages} for specifying the packages to * scan for annotated components. The package of each class specified will be scanned. * <p> * Consider creating a special no-op marker class or interface in each package that * serves no purpose other than being referenced by this attribute. * <p> * <strong>Note:</strong> this setting is an alias for * {@link ComponentScan @ComponentScan} only. It has no effect on {@code @Entity} * scanning or Spring Data {@link Repository} scanning. For those you should add * {@link org.springframework.boot.autoconfigure.domain.EntityScan @EntityScan} and * {@code @Enable...Repositories} annotations. * @return base packages to scan * @since 1.3.0 */ @AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses") Class<?>[] scanBasePackageClasses() default {}; /** * Specify whether {@link Bean @Bean} methods should get proxied in order to enforce * bean lifecycle behavior, e.g. to return shared singleton bean instances even in * case of direct {@code @Bean} method calls in user code. This feature requires * method interception, implemented through a runtime-generated CGLIB subclass which * comes with limitations such as the configuration class and its methods not being * allowed to declare {@code final}. * <p> * The default is {@code true}, allowing for 'inter-bean references' within the * configuration class as well as for external calls to this configuration's * {@code @Bean} methods, e.g. from another configuration class. If this is not needed * since each of this particular configuration's {@code @Bean} methods is * self-contained and designed as a plain factory method for container use, switch * this flag to {@code false} in order to avoid CGLIB subclass processing. * <p> * Turning off bean method interception effectively processes {@code @Bean} methods * individually like when declared on non-{@code @Configuration} classes, a.k.a. * "@Bean Lite Mode" (see {@link Bean @Bean's javadoc}). It is therefore behaviorally * equivalent to removing the {@code @Configuration} stereotype. * @since 2.2 * @return whether to proxy {@code @Bean} methods */ @AliasFor(annotation = Configuration.class) boolean proxyBeanMethods() default true; }

SpringBootConfiguration.java

他是一个容器

package org.springframework.boot; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.core.annotation.AliasFor; /** * Indicates that a class provides Spring Boot application * {@link Configuration @Configuration}. Can be used as an alternative to the Spring's * standard {@code @Configuration} annotation so that configuration can be found * automatically (for example in tests). * <p> * Application should only ever include <em>one</em> {@code @SpringBootConfiguration} and * most idiomatic Spring Boot applications will inherit it from * {@code @SpringBootApplication}. * * @author Phillip Webb * @author Andy Wilkinson * @since 1.4.0 */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Configuration public @interface SpringBootConfiguration { /** * Specify whether {@link Bean @Bean} methods should get proxied in order to enforce * bean lifecycle behavior, e.g. to return shared singleton bean instances even in * case of direct {@code @Bean} method calls in user code. This feature requires * method interception, implemented through a runtime-generated CGLIB subclass which * comes with limitations such as the configuration class and its methods not being * allowed to declare {@code final}. * <p> * The default is {@code true}, allowing for 'inter-bean references' within the * configuration class as well as for external calls to this configuration's * {@code @Bean} methods, e.g. from another configuration class. If this is not needed * since each of this particular configuration's {@code @Bean} methods is * self-contained and designed as a plain factory method for container use, switch * this flag to {@code false} in order to avoid CGLIB subclass processing. * <p> * Turning off bean method interception effectively processes {@code @Bean} methods * individually like when declared on non-{@code @Configuration} classes, a.k.a. * "@Bean Lite Mode" (see {@link Bean @Bean's javadoc}). It is therefore behaviorally * equivalent to removing the {@code @Configuration} stereotype. * @return whether to proxy {@code @Bean} methods * @since 2.2 */ @AliasFor(annotation = Configuration.class) boolean proxyBeanMethods() default true; }

EnableAutoConfiguration

开启自动装配的

/* * Copyright 2012-2019 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.boot.autoconfigure; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Inherited; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; import org.springframework.boot.autoconfigure.condition.ConditionalOnBean; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory; import org.springframework.boot.web.servlet.server.ServletWebServerFactory; import org.springframework.context.annotation.Conditional; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Import; import org.springframework.core.io.support.SpringFactoriesLoader; /** * Enable auto-configuration of the Spring Application Context, attempting to guess and * configure beans that you are likely to need. Auto-configuration classes are usually * applied based on your classpath and what beans you have defined. For example, if you * have {@code tomcat-embedded.jar} on your classpath you are likely to want a * {@link TomcatServletWebServerFactory} (unless you have defined your own * {@link ServletWebServerFactory} bean). * <p> * When using {@link SpringBootApplication @SpringBootApplication}, the auto-configuration * of the context is automatically enabled and adding this annotation has therefore no * additional effect. * <p> * Auto-configuration tries to be as intelligent as possible and will back-away as you * define more of your own configuration. You can always manually {@link #exclude()} any * configuration that you never want to apply (use {@link #excludeName()} if you don't * have access to them). You can also exclude them via the * {@code spring.autoconfigure.exclude} property. Auto-configuration is always applied * after user-defined beans have been registered. * <p> * The package of the class that is annotated with {@code @EnableAutoConfiguration}, * usually via {@code @SpringBootApplication}, has specific significance and is often used * as a 'default'. For example, it will be used when scanning for {@code @Entity} classes. * It is generally recommended that you place {@code @EnableAutoConfiguration} (if you're * not using {@code @SpringBootApplication}) in a root package so that all sub-packages * and classes can be searched. * <p> * Auto-configuration classes are regular Spring {@link Configuration @Configuration} * beans. They are located using the {@link SpringFactoriesLoader} mechanism (keyed * against this class). Generally auto-configuration beans are * {@link Conditional @Conditional} beans (most often using * {@link ConditionalOnClass @ConditionalOnClass} and * {@link ConditionalOnMissingBean @ConditionalOnMissingBean} annotations). * * @author Phillip Webb * @author Stephane Nicoll * @since 1.0.0 * @see ConditionalOnBean * @see ConditionalOnMissingBean * @see ConditionalOnClass * @see AutoConfigureAfter * @see SpringBootApplication */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @AutoConfigurationPackage @Import(AutoConfigurationImportSelector.class) public @interface EnableAutoConfiguration { String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration"; /** * Exclude specific auto-configuration classes such that they will never be applied. * @return the classes to exclude */ Class<?>[] exclude() default {}; /** * Exclude specific auto-configuration class names such that they will never be * applied. * @return the class names to exclude * @since 1.3.0 */ String[] excludeName() default {}; }

Import.java

package org.springframework.context.annotation; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * Indicates one or more <em>component classes</em> to import &mdash; typically * {@link Configuration @Configuration} classes. * * <p>Provides functionality equivalent to the {@code <import/>} element in Spring XML. * Allows for importing {@code @Configuration} classes, {@link ImportSelector} and * {@link ImportBeanDefinitionRegistrar} implementations, as well as regular component * classes (as of 4.2; analogous to {@link AnnotationConfigApplicationContext#register}). * * <p>{@code @Bean} definitions declared in imported {@code @Configuration} classes should be * accessed by using {@link org.springframework.beans.factory.annotation.Autowired @Autowired} * injection. Either the bean itself can be autowired, or the configuration class instance * declaring the bean can be autowired. The latter approach allows for explicit, IDE-friendly * navigation between {@code @Configuration} class methods. * * <p>May be declared at the class level or as a meta-annotation. * * <p>If XML or other non-{@code @Configuration} bean definition resources need to be * imported, use the {@link ImportResource @ImportResource} annotation instead. * * @author Chris Beams * @author Juergen Hoeller * @since 3.0 * @see Configuration * @see ImportSelector * @see ImportBeanDefinitionRegistrar * @see ImportResource */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface Import { /** * {@link Configuration @Configuration}, {@link ImportSelector}, * {@link ImportBeanDefinitionRegistrar}, or regular component classes to import. */ Class<?>[] value(); }

AutoConfigurationPackage.java

自动装配的选择器

/** * Indicates that the package containing the annotated class should be registered with * {@link AutoConfigurationPackages}. * * @author Phillip Webb * @since 1.3.0 * @see AutoConfigurationPackages */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @Import(AutoConfigurationPackages.Registrar.class) public @interface AutoConfigurationPackage { }

AutoConfigurationImportSelector

selectImports

选择想要导入装配的类

@Override public String[] selectImports(AnnotationMetadata annotationMetadata) { if (!isEnabled(annotationMetadata)) { return NO_IMPORTS; } AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader .loadMetadata(this.beanClassLoader); AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(autoConfigurationMetadata, annotationMetadata); return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations()); }

getAutoConfigurationEntry

List configurations = getCandidateConfigurations(annotationMetadata, attributes);获得候选和备用的配置

/** * Return the {@link AutoConfigurationEntry} based on the {@link AnnotationMetadata} * of the importing {@link Configuration @Configuration} class. * @param autoConfigurationMetadata the auto-configuration metadata * @param annotationMetadata the annotation metadata of the configuration class * @return the auto-configurations that should be imported */ protected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata, 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 = filter(configurations, autoConfigurationMetadata); fireAutoConfigurationImportEvents(configurations, exclusions); return new AutoConfigurationEntry(configurations, exclusions); }

getCandidateConfigurations

/** * Return the auto-configuration class names that should be considered. By default * this method will load candidates using {@link SpringFactoriesLoader} with * {@link #getSpringFactoriesLoaderFactoryClass()}. * @param metadata the source metadata * @param attributes the {@link #getAttributes(AnnotationMetadata) annotation * attributes} * @return a list of candidate configurations */ 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; }

spring.factories

org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\

EmbeddedWebServerFactoryCustomizerAutoConfiguration

springboot内置的tomcat

WebMvcAutoConfiguration

springMVC

ServletWebServerFactoryAutoConfiguration

web servers自动装配

启动Tomcat的命令

@ConditionalOnClass(name = "org.apache.catalina.startup.Tomcat")