1 分析之前的相关知识
1.1 ApplicationListener事件发布
写一个 DemoApplicationListener 实现 ApplicationListener 接口，并且把该组件加入到容器中。
...
@Component
public class DemoApplicationListener implements ApplicationListener {
@Override
public void onApplicationEvent(ApplicationEvent event) {
System.out.println("DemoApplicationListener 接受到了一个事件"+event);
}
}
扫描包
...
@ComponentScan(basePackages = {"com.demo.testapplicationlistener"})
public class MainConfig {
}
如果使用的默认的广播器，则直接发布时间。
...
public class MainClass {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);
ctx.publishEvent(new ApplicationEvent("我手动发布了一个事件") {
@Override
public Object getSource() {
return super.getSource();
}
});
ctx.close();
}
}
通过继承 SimpleApplicationEventMulticaster 定义广播器，实现广播器支持异步。
...
@Component(value = "applicationEventMulticaster")
public class DemoMulticaster extends SimpleApplicationEventMulticaster{
public TulingMulticaster () {
setTaskExecutor(Executors.newSingleThreadExecutor());
}
}
可以通过 BeanPostProcessor Bean的后置处理器，实现广播器支持异步。
...
@Component
public class MultiCasterBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
if(bean instanceof SimpleApplicationEventMulticaster) {
System.out.println("我拦截到了");
SimpleApplicationEventMulticaster simpleApplicationEventMulticaster= (SimpleApplicationEventMulticaster) bean;
simpleApplicationEventMulticaster.setTaskExecutor(Executors.newSingleThreadExecutor());
return bean;
}
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
return bean;
}
}
1.2 Bean的后置处理器（BeanPostProcessor）
// 见如上MultiCasterBeanPostProcessor
...
1.3 BeanFactory的后置处理器（BeanFactoryPostProcessor）
...
@Component
public class DemoBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("IOC 容器调用了DemoBeanFactoryPostProcessor的postProcessBeanFactory方法");
for(String name:beanFactory.getBeanDefinitionNames()) {
if("tulingLog".equals(name)) {
//从 BeanFactory 中获取BeanDefinition(Bean的定义类)
BeanDefinition beanDefinition = beanFactory.getBeanDefinition(name);
//将 Bean 定义为懒加载，当 Bean 第一次使用的时候实例化到容量。
beanDefinition.setLazyInit(true);
}
}
}
}
1.4 BeanDefinationRegister的后置处理器（BeanDefinitionRegistryPostProcessor）
...
@Component
public class DemoBeanDefinationRegisterPostProcessor implements BeanDefinitionRegistryPostProcessor {
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
System.out.println("DemoBeanDefinationRegisterPostProcessor的postProcessBeanDefinitionRegistry方法");
System.out.println("bean定义的数据量:"+registry.getBeanDefinitionCount());
RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(DemoLog.class);
//将DemoLog Bean定义注册到容器中
registry.registerBeanDefinition("demoLog",rootBeanDefinition);
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("DemoBeanDefinationRegisterPostProcessor的postProcessBeanFactory方法");
System.out.println(beanFactory.getBeanDefinitionCount());
}
}
2 源码分析
2.1 main 类入口
public class MainClass {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);
ctx.close();
}
}
扫描包
@Configuration
@ComponentScan(basePackages = "com.demo.testbeanfacotoryPostProcessor")
public class MainConfig {
}
2.2 创建 AnnotationConfigApplicationContext 构造方法
...
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
// 注册内部类添加到容器中(beanDefinitionMap，beanDefinitionNames)
// org.springframework.context.annotation.internalConfigurationAnnotationProcessor
// org.springframework.context.event.internalEventListenerFactory
// org.springframework.context.event.internalEventListenerProcessor
// org.springframework.context.annotation.internalAutowiredAnnotationProcessor
// org.springframework.context.annotation.internalRequiredAnnotationProcessor
this();
// 注册外部的注解类添加到容器中(beanDefinitionMap，beanDefinitionNames)
// mainConfig
register(annotatedClasses);
// 重点分析
// bean生命周期
refresh();
}
...
2.3 调用 org.springframework.context.support.AbstractApplicationContext#refresh
...
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// 重点分析
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
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();
}
}
}
...
2.4 调用 PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors(beanFactory, beanFactoryPostProcessors)
...
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
...
// 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<BeanDefinitionRegistryPostProcessor>();
// 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);
//重点分析
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
...
}
2.5 调用 PostProcessorRegistrationDelegate#invokeBeanDefinitionRegistryPostProcessors(postProcessors, registry)
/**
* Invoke the given BeanDefinitionRegistryPostProcessor beans.
*/
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
// 重点分析
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}
2.6 调用 ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry(registry)
...
/**
* Derive further bean definitions from the configuration classes in the registry.
*/
@Override
public void postProcessBeanDefinitionRegistry(registry) {
int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
}
if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanFactory already called on this post-processor against " + registry);
}
this.registriesPostProcessed.add(registryId);
processConfigBeanDefinitions(registry);
}
...
2.7 调用 ConfigurationClassPostProcessor#processConfigBeanDefinitions(registry)
/**
* Build and validate a configuration model based on the registry of
* {@link Configuration} classes.
*/
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
//第一步 过滤我们传入的主配置类
List<BeanDefinitionHolder> configCandidates = new ArrayList<BeanDefinitionHolder>();
String[] candidateNames = registry.getBeanDefinitionNames();
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// Return immediately if no @Configuration classes were found
if (configCandidates.isEmpty()) {
return;
}
//第二步 创建一个配置类解析器(ConfigurationClassParser)
// Parse each @Configuration class
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<BeanDefinitionHolder>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<ConfigurationClass>(configCandidates.size());
do {
parser.parse(candidates);
parser.validate();
Set<ConfigurationClass> configClasses = new LinkedHashSet<ConfigurationClass>(parser.getConfigurationClasses());
configClasses.removeAll(alreadyParsed);
// Read the model and create bean definitions based on its content
if (this.reader == null) {
this.reader = new ConfigurationClassBeanDefinitionReader(
registry, this.sourceExtractor, this.resourceLoader, this.environment,
this.importBeanNameGenerator, parser.getImportRegistry());
}
this.reader.loadBeanDefinitions(configClasses);
alreadyParsed.addAll(configClasses);
candidates.clear();
if (registry.getBeanDefinitionCount() > candidateNames.length) {
String[] newCandidateNames = registry.getBeanDefinitionNames();
Set<String> oldCandidateNames = new HashSet<String>(Arrays.asList(candidateNames));
Set<String> alreadyParsedClasses = new HashSet<String>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
if (!oldCandidateNames.contains(candidateName)) {
BeanDefinition bd = registry.getBeanDefinition(candidateName);
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(bd.getBeanClassName())) {
candidates.add(new BeanDefinitionHolder(bd, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
while (!candidates.isEmpty());
// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
if (sbr != null) {
if (!sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
}
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
}
}
见下图
