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springboot 系列之启动流程
Springboot 简介
springboot 封装了 Spring 组件，基于约定优于配置。晋升了开发效率，本文次要解说 springboot 框架的启动过程。
启动流程剖析
1、首先，咱们看一下启动类 SpringApplication, 它是位于 org.springframework.boot 包上面的。我的项目启动类源码
@SpringBootApplication
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);
}
}这里用到了 SpringBootApplication 注解，而后在 main 办法中启动 boot 利用。
2、咱们接下来看看 SpringBootApplication 注解的源码
@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 {
/**
* 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.
* @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.
* @return base packages to scan
* @since 1.3.0
*/
@AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
Class<?>[] scanBasePackageClasses() default {};}它是位于 org.springframework.boot.autoconfigure 包上面的。咱们能够看到它依赖了几个重要的注解 SpringBootConfiguration、EnableAutoConfiguration、ComponentScan 这三个注解。其中 EnableAutoConfiguration 就是 springboot 主动配置用到的类，在接下来咱们将会重点介绍。
3、咱们在看 SpringApplication 运行的 run 办法
/**
* Static helper that can be used to run a {@link SpringApplication} from the
* specified sources using default settings and user supplied arguments.
* @param primarySources the primary sources to load
* @param args the application arguments (usually passed from a Java main method)
* @return the running {@link ApplicationContext}
*/
public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {return new SpringApplication(primarySources).run(args);
}首先，创立 SpringApplication 利用对象，而后调用 run 办法传入启动参数
public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
this.resourceLoader = resourceLoader;
Assert.notNull(primarySources, "PrimarySources must not be null");
this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
this.webApplicationType = WebApplicationType.deduceFromClasspath();
setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
this.mainApplicationClass = deduceMainApplicationClass();} this.webApplicationType = WebApplicationType.deduceFromClasspath();
setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
this.mainApplicationClass = deduceMainApplicationClass();这是创建对象的办法，先校验启动类，而后调用 deduceFromClasspath 办法推断一个利用类型（是否是 web 我的项目）初始化工厂类，设置 Spring 监听器（观察者模式）。
4、创立好对象后，咱们接着看 run 办法
/**
* Run the Spring application, creating and refreshing a new
* {@link ApplicationContext}.
* @param args the application arguments (usually passed from a Java main method)
* @return a running {@link ApplicationContext}
*/
public ConfigurableApplicationContext run(String... args) {
// 开启系统启动工夫监听
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
// 创立一场报告汇合
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
// 配置检测无显示器也能够启动
configureHeadlessProperty();
// 获取运行监听器，获取事件公布监听
SpringApplicationRunListeners listeners = getRunListeners(args);
// 启动监听器
listeners.starting();
try {
// 通过启动参数构建利用参数
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
// 创立上线文环境
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
// 配置疏忽的 bean 信息
configureIgnoreBeanInfo(environment);
// 打印 boot 启动 logo
Banner printedBanner = printBanner(environment);
// 创立上线文（容器）context = createApplicationContext();
// 获取异样汇合
exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class}, context);
// 筹备上下文
prepareContext(context, environment, listeners, applicationArguments, printedBanner);
// 刷新上下文（重点）refreshContext(context);
// 刷新之后
afterRefresh(context, applicationArguments);
// 关闭系统工夫监听
stopWatch.stop();
// 打印日志
if (this.logStartupInfo) {new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {listeners.running(context);
}
catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}咱们只看几个重要的办法，首先看 createApplicationContext() 创立上下文（容器）办法
/**
* Strategy method used to create the {@link ApplicationContext}. By default this
* method will respect any explicitly set application context or application context
* class before falling back to a suitable default.
* @return the application context (not yet refreshed)
* @see #setApplicationContextClass(Class)
*/
protected ConfigurableApplicationContext createApplicationContext() {
// 获取启动类
Class<?> contextClass = this.applicationContextClass;
// 推断上下文类型，默认 web 类型，if (contextClass == null) {
try {switch (this.webApplicationType) {
case SERVLET:
contextClass = Class.forName(DEFAULT_SERVLET_WEB_CONTEXT_CLASS);
break;
//flux 类型上下文
case REACTIVE:
contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS);
break;
default:
contextClass = Class.forName(DEFAULT_CONTEXT_CLASS);
}
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Unable create a default ApplicationContext," + "please specify an ApplicationContextClass",
ex);
}
}
// 实例化上下文，容器
return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
}咱们在看，prepareContext(context, environment, listeners, applicationArguments, printedBanner); 筹备上下文办法
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {
// 设置上下文环境
context.setEnvironment(environment);
// 解决利用上下文
postProcessApplicationContext(context);
// 利用初始化类
applyInitializers(context);
// 监听器筹备上下文
listeners.contextPrepared(context);
if (this.logStartupInfo) {logStartupInfo(context.getParent() == null);
logStartupProfileInfo(context);
}
// Add boot specific singleton beans
// 创立 bean 工厂
ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
// 注册利用参数 bean
beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
if (printedBanner != null) {beanFactory.registerSingleton("springBootBanner", printedBanner);
}
if (beanFactory instanceof DefaultListableBeanFactory) {((DefaultListableBeanFactory) beanFactory)
.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
}
// Load the sources
Set<Object> sources = getAllSources();
Assert.notEmpty(sources, "Sources must not be empty");
load(context, sources.toArray(new Object[0]));
listeners.contextLoaded(context);
}在看、重要的 refreshContext(context); 刷新上下文办法重点
private void refreshContext(ConfigurableApplicationContext context) {refresh(context);
if (this.registerShutdownHook) {
try {context.registerShutdownHook();
}
catch (AccessControlException ex) {// Not allowed in some environments.}
}
}点进去 refresh(context); 办法进入
/**
* Refresh the underlying {@link ApplicationContext}.
* @param applicationContext the application context to refresh
*/
protected void refresh(ApplicationContext applicationContext) {Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext);
((AbstractApplicationContext) applicationContext).refresh();}类型转换为 AbstractApplicationContext，持续看 refresh 办法
@Override
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {
// 筹备刷新
prepareRefresh();
// 刷新子类工厂
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// 筹备 beanFactory
prepareBeanFactory(beanFactory);
try {
// 解决 bean 工厂
postProcessBeanFactory(beanFactory);
// 调用 bean 共产处理器重点
invokeBeanFactoryPostProcessors(beanFactory);
// 注册 bean 工厂处理器
registerBeanPostProcessors(beanFactory);
// 初始化音讯类
initMessageSource();
// 初始化利用事件播送
initApplicationEventMulticaster();
// 正在刷新的
onRefresh();
// 公布事件监听器
registerListeners();
// 实现 bean 工厂注册
finishBeanFactoryInitialization(beanFactory);
// 实现事件刷新
finishRefresh();}
catch (BeansException ex) {if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization -" +
"cancelling refresh attempt:" + ex);
}
// Destroy already created singletons to avoid dangling resources.
destroyBeans();
// Reset 'active' flag.
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();}
}
}
咱们在看 prepareRefresh 筹备刷新办法
/**
* Prepare this context for refreshing, setting its startup date and
* active flag as well as performing any initialization of property sources.
*/
protected void prepareRefresh() {
// 启动利用开关
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
// 设置启动状态
this.active.set(true);
if (logger.isDebugEnabled()) {if (logger.isTraceEnabled()) {logger.trace("Refreshing" + this);
}
else {logger.debug("Refreshing" + getDisplayName());
}
}
// 初始化属性类
initPropertySources();
// 校验属性
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
if (this.earlyApplicationListeners == null) {this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// Reset local application listeners to pre-refresh state.
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
this.earlyApplicationEvents = new LinkedHashSet<>();}
在看 prepareBeanFactory 筹备配置工厂办法
/**
* Configure the factory's standard context characteristics,
* such as the context's ClassLoader and post-processors.
* @param beanFactory the BeanFactory to configure
*/
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 设置类加载器
beanFactory.setBeanClassLoader(getClassLoader());
// 设置 bean 表达式解决
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
// 设置属性编辑器注册
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// 配置 bean 处理器，后置解决
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// BeanFactory interface not registered as resolvable type in a plain factory.
// MessageSource registered (and found for autowiring) as a bean.
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// 增加事件监听处理器
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// Set a temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
// Register default environment beans.
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {// 注册环境 bean beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
}
if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
}
}在看 postProcessBeanFactory(beanFactory); 解决工厂类（子类）
在 ServletWebServerApplicationContext 类中实现了这个办法
@Override
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {beanFactory.addBeanPostProcessor(new WebApplicationContextServletContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(ServletContextAware.class);
registerWebApplicationScopes();}在看 invokeBeanFactoryPostProcessors(beanFactory); 调用 bean 工厂处理器办法
/**
* Instantiate and invoke all registered BeanFactoryPostProcessor beans,
* respecting explicit order if given.
* <p>Must be called before singleton instantiation.
*/
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {// 解决工厂类代表 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}点进去看看
public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
if (beanFactory instanceof BeanDefinitionRegistry) {BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {regularPostProcessors.add(postProcessor);
}
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// Separate between BeanDefinitionRegistryPostProcessors that implement
// PriorityOrdered, Ordered, and the rest.
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
boolean reiterate = true;
while (reiterate) {
reiterate = false;
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {if (!processedBeans.contains(ppName)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
reiterate = true;
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {if (processedBeans.contains(ppName)) {// skip - already processed in first phase above}
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {orderedPostProcessorNames.add(ppName);
}
else {nonOrderedPostProcessorNames.add(ppName);
}
}
// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
for (String postProcessorName : orderedPostProcessorNames) {orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
for (String postProcessorName : nonOrderedPostProcessorNames) {nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
beanFactory.clearMetadataCache();}点进去 invokeBeanFactoryPostProcessors 办法
/**
* Invoke the given BeanFactoryPostProcessor beans.
*/
private static void invokeBeanFactoryPostProcessors(Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {for (BeanFactoryPostProcessor postProcessor : postProcessors) {postProcessor.postProcessBeanFactory(beanFactory);
}
}点击 postProcessBeanFactory(beanFactory); 找到实现类
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {int factoryId = System.identityHashCode(beanFactory);
if (this.factoriesPostProcessed.contains(factoryId)) {
throw new IllegalStateException("postProcessBeanFactory already called on this post-processor against" + beanFactory);
}
this.factoriesPostProcessed.add(factoryId);
if (!this.registriesPostProcessed.contains(factoryId)) {
// BeanDefinitionRegistryPostProcessor hook apparently not supported...
// Simply call processConfigurationClasses lazily at this point then.
processConfigBeanDefinitions((BeanDefinitionRegistry) beanFactory);
}
enhanceConfigurationClasses(beanFactory);
beanFactory.addBeanPostProcessor(new ImportAwareBeanPostProcessor(beanFactory));
}点击 processConfigBeanDefinitions((BeanDefinitionRegistry) beanFactory); 办法找到
// Parse each @Configuration class
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
do {parser.parse(candidates);
parser.validate();
Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses());
configClasses.removeAll(alreadyParsed);持续找 parse 办法, 找到 ConfigurationClassParser 类这个办法，接着找
@Nullable
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
throws IOException {// Process any @Import annotations
processImports(configClass, sourceClass, getImports(sourceClass), true);
// Process any @ImportResource annotations
AnnotationAttributes importResource =
AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
if (importResource != null) {String[] resources = importResource.getStringArray("locations");
Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
for (String resource : resources) {String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
configClass.addImportedResource(resolvedResource, readerClass);
}
}
// Process individual @Bean methods
Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
for (MethodMetadata methodMetadata : beanMethods) {configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
// Process default methods on interfaces
processInterfaces(configClass, sourceClass);
// Process superclass, if any
if (sourceClass.getMetadata().hasSuperClass()) {String superclass = sourceClass.getMetadata().getSuperClassName();
if (superclass != null && !superclass.startsWith("java") &&
!this.knownSuperclasses.containsKey(superclass)) {this.knownSuperclasses.put(superclass, configClass);
// Superclass found, return its annotation metadata and recurse
return sourceClass.getSuperClass();}
}
// No superclass -> processing is complete
return null; 咱们找到 processImports 的解决中央 this.importStack.push(configClass);
try {for (SourceClass candidate : importCandidates) {if (candidate.isAssignable(ImportSelector.class)) {
// Candidate class is an ImportSelector -> delegate to it to determine imports
Class<?> candidateClass = candidate.loadClass();
ImportSelector selector = BeanUtils.instantiateClass(candidateClass, ImportSelector.class);
ParserStrategyUtils.invokeAwareMethods(selector, this.environment, this.resourceLoader, this.registry);
if (selector instanceof DeferredImportSelector) {this.deferredImportSelectorHandler.handle(configClass, (DeferredImportSelector) selector);
}
else {String[] importClassNames = selector.selectImports(currentSourceClass.getMetadata());
Collection<SourceClass> importSourceClasses = asSourceClasses(importClassNames);
processImports(configClass, currentSourceClass, importSourceClasses, false);
}
}
else if (candidate.isAssignable(ImportBeanDefinitionRegistrar.class)) {
// Candidate class is an ImportBeanDefinitionRegistrar ->
// delegate to it to register additional bean definitions
Class<?> candidateClass = candidate.loadClass();
ImportBeanDefinitionRegistrar registrar =
BeanUtils.instantiateClass(candidateClass, ImportBeanDefinitionRegistrar.class);
ParserStrategyUtils.invokeAwareMethods(registrar, this.environment, this.resourceLoader, this.registry);
configClass.addImportBeanDefinitionRegistrar(registrar, currentSourceClass.getMetadata());
}
else {
// Candidate class not an ImportSelector or ImportBeanDefinitionRegistrar ->
// process it as an @Configuration class
this.importStack.registerImport(currentSourceClass.getMetadata(), candidate.getMetadata().getClassName());
processConfigurationClass(candidate.asConfigClass(configClass));
}
}
}ImportSelector 接口解决的中央，主动配置内部 bean 的办法
接下来，看 registerBeanPostProcessors(beanFactory); 注册 bean 处理器工厂
而后，看 onRefresh 办法 @Override
protected void onRefresh() {super.onRefresh();
try {createWebServer();
}
catch (Throwable ex) {throw new ApplicationContextException("Unable to start web server", ex);
}
} 在这里创立 web 容器
实现刷新，利用启动实现，还有细节结下来在细说。有问题，请留言！集体博客地址
正文完
发表至： springboot
2020-07-19
