xml/properties
classpath/network/filesystem/servletContext
BeanDefintion
策略模式
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public class MainTest {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
}
}
// 从ClassPathXmlApplicationContext开始 public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
//1、调用容器准备刷新的方法，获取容器的当时时间，同时给容器设置同步标识
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
//2、告诉子类启动refreshBeanFactory()方法，Bean定义资源文件的载入从
//子类的refreshBeanFactory()方法启动
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
//3、为BeanFactory配置容器特性，例如类加载器、事件处理器等
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
//4、为容器的某些子类指定特殊的BeanPost事件处理器
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
//5、调用所有注册的BeanFactoryPostProcessor的Bean
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
//6、为BeanFactory注册BeanPost事件处理器.
//BeanPostProcessor是Bean后置处理器，用于监听容器触发的事件
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
//7、初始化信息源，和国际化相关.
initMessageSource();
// Initialize event multicaster for this context.
//8、初始化容器事件传播器.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
//9、调用子类的某些特殊Bean初始化方法
onRefresh();
// Check for listener beans and register them.
//10、为事件传播器注册事件监听器.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
//11、初始化所有剩余的单例Bean
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
//12、初始化容器的生命周期事件处理器，并发布容器的生命周期事件
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.
//13、销毁已创建的Bean
destroyBeans();
// Reset 'active' flag.
//14、取消refresh操作，重置容器的同步标识。
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...
//15、重设公共缓存
resetCommonCaches();
}
}
}
//Bean定义读取器向容器注册注解Bean定义类
<T> void doRegisterBean(Class<T> annotatedClass, @Nullable Supplier<T> instanceSupplier, @Nullable String name,
@Nullable Class<? extends Annotation>[] qualifiers, BeanDefinitionCustomizer... definitionCustomizers) {
//根据指定的注解Bean定义类，创建Spring容器中对注解Bean的封装的数据结构
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
abd.setInstanceSupplier(instanceSupplier);
//解析注解Bean定义的作用域，若@Scope("prototype")，则Bean为原型类型；
//若@Scope("singleton")，则Bean为单态类型
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
//为注解Bean定义设置作用域
abd.setScope(scopeMetadata.getScopeName());
//为注解Bean定义生成Bean名称
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
//处理注解Bean定义中的通用注解
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
//如果在向容器注册注解Bean定义时，使用了额外的限定符注解，则解析限定符注解。
//主要是配置的关于autowiring自动依赖注入装配的限定条件，即@Qualifier注解
//Spring自动依赖注入装配默认是按类型装配，如果使用@Qualifier则按名称
if (qualifiers != null) {
for (Class<? extends Annotation> qualifier : qualifiers) {
//如果配置了@Primary注解，设置该Bean为autowiring自动依赖注入装//配时的首选
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
//如果配置了@Lazy注解，则设置该Bean为非延迟初始化，如果没有配置，
//则该Bean为预实例化
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
//如果使用了除@Primary和@Lazy以外的其他注解，则为该Bean添加一
//个autowiring自动依赖注入装配限定符，该Bean在进autowiring
//自动依赖注入装配时，根据名称装配限定符指定的Bean
else {
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
for (BeanDefinitionCustomizer customizer : definitionCustomizers) {
customizer.customize(abd);
}
//创建一个指定Bean名称的Bean定义对象，封装注解Bean定义类数据
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
//根据注解Bean定义类中配置的作用域，创建相应的代理对象
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
//向IOC容器注册注解Bean类定义对象
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}