dubbo-spring-boot-autoconfigure-compatible中注入ServiceAnnotationBeanPostProcessor进行初始化，ServiceAnnotationBeanPostProcessor继承了ServiceClassPostProcessor,ServiceClassPostProcessor实现了BeanDefinitionRegistryPostProcessor中的方法postProcessBeanDefinitionRegistry。
再看org.springframework.context.support.AbstractApplicationContext#refresh中的invokeBeanFactoryPostProcessors(beanFactory)用来找出所有beanFactory后置处理器，并且调用这些处理器来改变bean的定义。
invokeBeanFactoryPostProcessors(beanFactory)实际上是委托org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());方法处理的。
在PostProcessorRegistrationDelegate中invokeBeanFactoryPostProcessors方法调用了BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry接口，所有实现postProcessBeanDefinitionRegistry接口的bean都会被调用，包括ServiceClassPostProcessor,这里初始化了DubboBootstrapApplicationListener，当监听到ContextRefreshedEvent事件之后，触发dubbo服务启动dubboBootstrap.start(),调用ServiceConfig.export()，这个方法会启动一个网络监听，从而实现服务发布。具体怎么实现服务发布会在之后的文章做介绍
public class DubboAutoConfiguration {
@ConditionalOnProperty(prefix = DUBBO_SCAN_PREFIX, name = BASE_PACKAGES_PROPERTY_NAME)
@ConditionalOnBean(name = BASE_PACKAGES_PROPERTY_RESOLVER_BEAN_NAME)
@Bean
public ServiceAnnotationBeanPostProcessor serviceAnnotationBeanPostProcessor(
@Qualifier(BASE_PACKAGES_PROPERTY_RESOLVER_BEAN_NAME) PropertyResolver propertyResolver) {
Set<String> packagesToScan = propertyResolver.getProperty(BASE_PACKAGES_PROPERTY_NAME, Set.class, emptySet());
return new ServiceAnnotationBeanPostProcessor(packagesToScan);
}
......
}
public class ServiceAnnotationBeanPostProcessor extends ServiceClassPostProcessor {
public ServiceAnnotationBeanPostProcessor(String... packagesToScan) {
this(Arrays.asList(packagesToScan));
}
public ServiceAnnotationBeanPostProcessor(Collection<String> packagesToScan) {
this(new LinkedHashSet<>(packagesToScan));
}
public ServiceAnnotationBeanPostProcessor(Set<String> packagesToScan) {
super(packagesToScan);
}
}
public class ServiceClassPostProcessor implements BeanDefinitionRegistryPostProcessor, EnvironmentAware,
ResourceLoaderAware, BeanClassLoaderAware {
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
// @since 2.7.5
registerBeans(registry, DubboBootstrapApplicationListener.class);
Set<String> resolvedPackagesToScan = resolvePackagesToScan(packagesToScan);
if (!CollectionUtils.isEmpty(resolvedPackagesToScan)) {
registerServiceBeans(resolvedPackagesToScan, registry);
} else {
if (logger.isWarnEnabled()) {
logger.warn("packagesToScan is empty , ServiceBean registry will be ignored!");
}
}
}
......
}
public abstract class AbstractApplicationContext extends DefaultResourceLoader
implements ConfigurableApplicationContext, DisposableBean {
......
@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);
// 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();
}
}
}
......
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
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()));
}
}
}
class PostProcessorRegistrationDelegate {
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<String>();
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
}
}
......
}
public class ServiceClassPostProcessor implements BeanDefinitionRegistryPostProcessor, EnvironmentAware,
ResourceLoaderAware, BeanClassLoaderAware {
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
// @since 2.7.5
registerBeans(registry, DubboBootstrapApplicationListener.class);
Set<String> resolvedPackagesToScan = resolvePackagesToScan(packagesToScan);
if (!CollectionUtils.isEmpty(resolvedPackagesToScan)) {
registerServiceBeans(resolvedPackagesToScan, registry);
} else {
if (logger.isWarnEnabled()) {
logger.warn("packagesToScan is empty , ServiceBean registry will be ignored!");
}
}
}
}
public class DubboBootstrapApplicationListener extends OneTimeExecutionApplicationContextEventListener
implements Ordered {
@Override
public void onApplicationContextEvent(ApplicationContextEvent event) {
if (event instanceof ContextRefreshedEvent) {
onContextRefreshedEvent((ContextRefreshedEvent) event);
} else if (event instanceof ContextClosedEvent) {
onContextClosedEvent((ContextClosedEvent) event);
}
}
private void onContextRefreshedEvent(ContextRefreshedEvent event) {
dubboBootstrap.start();
}
}
