1.Java Spring框架源码分析-AOP-给容器中注入AspectJAnnotationAutoProxyCreator组件

目录

• 1. 开启AOP
• 2. 注册AspectJAnnotationAutoProxyCreator组件
• 3. ImportBeanDefinitionRegistrar的registerBeanDefinitions是什么步骤被调用的
  • 3.1. 跟踪ConfigurationClassProprocessor的postProcessBeanDefinitionRegistry方法

一般我们开启aop的功能是通过@EnableAspectJAutoProxy，所以首先查看其源码

1. 开启AOP

• @EnableAspectJAutoProxy

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(AspectJAutoProxyRegistrar.class)//给容器中导入AspectJAutoProxyRegistrar组件
public @interface EnableAspectJAutoProxy {
	boolean proxyTargetClass() default false;
	boolean exposeProxy() default false;

}

关键在于导入的AspectJAutoProxyRegistrar这个类，他想容器中注入了一些组件

2. 注册AspectJAnnotationAutoProxyCreator组件

• AspectJAutoProxyRegistrar registerBeanDefinitions

class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar {//继承了ImportBeanDefinitionRegistrar

	//重写的这个方法可以先容器中注入bean的class
	@Override
	public void registerBeanDefinitions(
			AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {

		//这里打一个断点
		//这个名字的意思是如果需要的话注入AspectJAnnotationAutoProxyCreator这个bean的class
		AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);

		//从EnableAspectJAutoProxyv中获取proxyTargetClass和exposeProxy进行处理
		AnnotationAttributes enableAspectJAutoProxy =
				AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class);
		if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) {
			AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
		}
		if (enableAspectJAutoProxy.getBoolean("exposeProxy")) {
			AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry);
		}
	}

}

• AopConfigUtils registerAspectJAnnotationAutoProxyCreatorIfNecessary

public abstract class AopConfigUtils {
	public static final String AUTO_PROXY_CREATOR_BEAN_NAME =
			"org.springframework.aop.config.internalAutoProxyCreator";

	public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry) {
		return registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry, null);
	}

	public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
		return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);
	}

	private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry, Object source) {
		Assert.notNull(registry, "BeanDefinitionRegistry must not be null");

		//是否已经注册了org.springframework.aop.config.internalAutoProxyCreator
		//没有的话走30行
		if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {
			BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);
			if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
				int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName());
				int requiredPriority = findPriorityForClass(cls);
				if (currentPriority < requiredPriority) {
					apcDefinition.setBeanClassName(cls.getName());
				}
			}
			return null;
		}

		//将org.springframework.aop.config.internalAutoProxyCreator:AnnotationAwareAspectJAutoProxyCreator.class
		//注册进容器中
		RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
		beanDefinition.setSource(source);
		beanDefinition.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE);
		beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
		registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition);
		return beanDefinition;
	}
}

3. ImportBeanDefinitionRegistrar的registerBeanDefinitions是什么步骤被调用的

在这个方法上打个断点，调试调用栈如下：

registerBeanDefinitions:45, AspectJAutoProxyRegistrar (org.springframework.context.annotation)
loadBeanDefinitionsFromRegistrars:360, ConfigurationClassBeanDefinitionReader (org.springframework.context.annotation)
loadBeanDefinitionsForConfigurationClass:144, ConfigurationClassBeanDefinitionReader (org.springframework.context.annotation)
loadBeanDefinitions:116, ConfigurationClassBeanDefinitionReader (org.springframework.context.annotation)
processConfigBeanDefinitions:320, ConfigurationClassPostProcessor (org.springframework.context.annotation)
postProcessBeanDefinitionRegistry:228, ConfigurationClassPostProcessor (org.springframework.context.annotation)
invokeBeanDefinitionRegistryPostProcessors:272, PostProcessorRegistrationDelegate (org.springframework.context.support)
invokeBeanFactoryPostProcessors:92, PostProcessorRegistrationDelegate (org.springframework.context.support)
invokeBeanFactoryPostProcessors:687, AbstractApplicationContext (org.springframework.context.support)
refresh:524, AbstractApplicationContext (org.springframework.context.support)
<init>:84, AnnotationConfigApplicationContext (org.springframework.context.annotation)
main:26, AopConfig

参考2.调用BeanFactoryPostProcessor的postProcess方法.md 先调用PriorityOrdered类型的postProcessBeanDefinitionRegistry方法

可以发现调用的是ConfigurationClassProprocessor的postProcessBeanDefinitionRegistry方法

3.1. 跟踪ConfigurationClassProprocessor的postProcessBeanDefinitionRegistry方法

• ConfigurationClassProprocessor postProcessBeanDefinitionRegistry

public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
	//...

	processConfigBeanDefinitions(registry);//这里
}

• ConfigurationClassProprocessor processConfigBeanDefinitions

public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
	//...
	//这里configClasses包含了我们自己的AopCofig这个@Configuration
	this.reader.loadBeanDefinitions(configClasses);
	//...
}

接着就是

• ConfigurationClassBeanDefinitionReader#loadBeanDefinitions

public void loadBeanDefinitions(Set<ConfigurationClass> configurationModel) {
	TrackedConditionEvaluator trackedConditionEvaluator = new TrackedConditionEvaluator();
	for (ConfigurationClass configClass : configurationModel) {
		loadBeanDefinitionsForConfigurationClass(configClass, trackedConditionEvaluator);//这里
	}
}

• ConfigurationClassBeanDefinitionReader#loadBeanDefinitionsForConfigurationClass

private void loadBeanDefinitionsForConfigurationClass(
		ConfigurationClass configClass, TrackedConditionEvaluator trackedConditionEvaluator) {

	//...
	loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
}

• ConfigurationClassBeanDefinitionReader#loadBeanDefinitionsFromRegistrars

private void loadBeanDefinitionsFromRegistrars(Map<ImportBeanDefinitionRegistrar, AnnotationMetadata> registrars) {
	for (Map.Entry<ImportBeanDefinitionRegistrar, AnnotationMetadata> entry : registrars.entrySet()) {
		entry.getKey().registerBeanDefinitions(entry.getValue(), this.registry);
	}
}

最后调用到了AspectJAutoProxyRegistrar#registerBeanDefinitions