Spring原始碼之@Configuration原理
總結
- 將@PropertySource、@ComponentScan、@Import、@ImportResource、@Bean等直接註解的類的BeanDefinition,是在ConfigurationClassParser#parse()中直接進行載入註冊
- 通過ConfigurationClassBeanDefinitionReader#loadBeanDefinitions()開始將@Configuration註解類內部@Import、@Bean進行BeanDefinition的載入註冊
簡單例子
@Configuration public class ConfigTest { @Bean public ConfigBean configBean() { return new ConfigBean(); } }
public class ConfigBean {......}
ConfigurationClassParser#parse()掃描出configClasses
springboot啟動時,在AbstractApplicationContext#refresh()中invokeBeanFactoryPostProcessors(beanFactory)會將@PropertySource、@ComponentScan、@Import、@ImportResource、@Bean註解的類進行生成BeanDefinition,並載入註冊。並將ConfigurationClass進行快取
private final Map<ConfigurationClass, ConfigurationClass> configurationClasses = new LinkedHashMap<>(); protected void processConfigurationClass(ConfigurationClass configClass, Predicate<String> filter) throws IOException { this.configurationClasses.put(configClass, configClass); }
詳見前文《Spring原始碼之IOC容器建立、BeanDefinition載入和註冊和IOC容器依賴注入》
loadBeanDefinitions處理
呼叫鏈:
AbstractApplicationContext#refresh() --> AbstractApplicationContext#invokeBeanFactoryPostProcessors() --> PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors() --> PostProcessorRegistrationDelegate#invokeBeanDefinitionRegistryPostProcessors() --> ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry()--> ConfigurationClassPostProcessor#processConfigBeanDefinitions() --> ConfigurationClassBeanDefinitionReader#loadBeanDefinitions() --> ConfigurationClassBeanDefinitionReader#loadBeanDefinitionsForConfigurationClass()
private void loadBeanDefinitionsForConfigurationClass(
ConfigurationClass configClass, TrackedConditionEvaluator trackedConditionEvaluator) {
if (trackedConditionEvaluator.shouldSkip(configClass)) {
String beanName = configClass.getBeanName();
if (StringUtils.hasLength(beanName) && this.registry.containsBeanDefinition(beanName)) {
this.registry.removeBeanDefinition(beanName);
}
this.importRegistry.removeImportingClass(configClass.getMetadata().getClassName());
return;
}
//@Configuration註解內部@Import註解方法處理
if (configClass.isImported()) {
registerBeanDefinitionForImportedConfigurationClass(configClass);
}
//@Configuration註解內部@Bean註解方法處理
for (BeanMethod beanMethod : configClass.getBeanMethods()) {
loadBeanDefinitionsForBeanMethod(beanMethod);
}
loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
}
處理Bean的一系列屬性後,向IOC容器中開始註冊。this.registry.registerBeanDefinition(),註冊邏輯可詳見前文。
/**
* Read the given {@link BeanMethod}, registering bean definitions
* with the BeanDefinitionRegistry based on its contents.
*/
@SuppressWarnings("deprecation") // for RequiredAnnotationBeanPostProcessor.SKIP_REQUIRED_CHECK_ATTRIBUTE
private void loadBeanDefinitionsForBeanMethod(BeanMethod beanMethod) {
ConfigurationClass configClass = beanMethod.getConfigurationClass();
MethodMetadata metadata = beanMethod.getMetadata();
String methodName = metadata.getMethodName();
// Do we need to mark the bean as skipped by its condition?
if (this.conditionEvaluator.shouldSkip(metadata, ConfigurationPhase.REGISTER_BEAN)) {
configClass.skippedBeanMethods.add(methodName);
return;
}
if (configClass.skippedBeanMethods.contains(methodName)) {
return;
}
AnnotationAttributes bean = AnnotationConfigUtils.attributesFor(metadata, Bean.class);
Assert.state(bean != null, "No @Bean annotation attributes");
// Consider name and any aliases
List<String> names = new ArrayList<>(Arrays.asList(bean.getStringArray("name")));
String beanName = (!names.isEmpty() ? names.remove(0) : methodName);
// Register aliases even when overridden
for (String alias : names) {
this.registry.registerAlias(beanName, alias);
}
// Has this effectively been overridden before (e.g. via XML)?
if (isOverriddenByExistingDefinition(beanMethod, beanName)) {
if (beanName.equals(beanMethod.getConfigurationClass().getBeanName())) {
throw new BeanDefinitionStoreException(beanMethod.getConfigurationClass().getResource().getDescription(),
beanName, "Bean name derived from @Bean method '" + beanMethod.getMetadata().getMethodName() +
"' clashes with bean name for containing configuration class; please make those names unique!");
}
return;
}
ConfigurationClassBeanDefinition beanDef = new ConfigurationClassBeanDefinition(configClass, metadata, beanName);
beanDef.setSource(this.sourceExtractor.extractSource(metadata, configClass.getResource()));
if (metadata.isStatic()) {
// static @Bean method
if (configClass.getMetadata() instanceof StandardAnnotationMetadata) {
beanDef.setBeanClass(((StandardAnnotationMetadata) configClass.getMetadata()).getIntrospectedClass());
}
else {
beanDef.setBeanClassName(configClass.getMetadata().getClassName());
}
beanDef.setUniqueFactoryMethodName(methodName);
}
else {
// instance @Bean method
beanDef.setFactoryBeanName(configClass.getBeanName());
beanDef.setUniqueFactoryMethodName(methodName);
}
if (metadata instanceof StandardMethodMetadata) {
beanDef.setResolvedFactoryMethod(((StandardMethodMetadata) metadata).getIntrospectedMethod());
}
beanDef.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_CONSTRUCTOR);
beanDef.setAttribute(org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor.
SKIP_REQUIRED_CHECK_ATTRIBUTE, Boolean.TRUE);
AnnotationConfigUtils.processCommonDefinitionAnnotations(beanDef, metadata);
Autowire autowire = bean.getEnum("autowire");
if (autowire.isAutowire()) {
beanDef.setAutowireMode(autowire.value());
}
boolean autowireCandidate = bean.getBoolean("autowireCandidate");
if (!autowireCandidate) {
beanDef.setAutowireCandidate(false);
}
String initMethodName = bean.getString("initMethod");
if (StringUtils.hasText(initMethodName)) {
beanDef.setInitMethodName(initMethodName);
}
String destroyMethodName = bean.getString("destroyMethod");
beanDef.setDestroyMethodName(destroyMethodName);
// Consider scoping
ScopedProxyMode proxyMode = ScopedProxyMode.NO;
AnnotationAttributes attributes = AnnotationConfigUtils.attributesFor(metadata, Scope.class);
if (attributes != null) {
beanDef.setScope(attributes.getString("value"));
proxyMode = attributes.getEnum("proxyMode");
if (proxyMode == ScopedProxyMode.DEFAULT) {
proxyMode = ScopedProxyMode.NO;
}
}
// Replace the original bean definition with the target one, if necessary
BeanDefinition beanDefToRegister = beanDef;
if (proxyMode != ScopedProxyMode.NO) {
BeanDefinitionHolder proxyDef = ScopedProxyCreator.createScopedProxy(
new BeanDefinitionHolder(beanDef, beanName), this.registry,
proxyMode == ScopedProxyMode.TARGET_CLASS);
beanDefToRegister = new ConfigurationClassBeanDefinition(
(RootBeanDefinition) proxyDef.getBeanDefinition(), configClass, metadata, beanName);
}
if (logger.isTraceEnabled()) {
logger.trace(String.format("Registering bean definition for @Bean method %s.%s()",
configClass.getMetadata().getClassName(), beanName));
}
this.registry.registerBeanDefinition(beanName, beanDefToRegister);
}