Spring源码BeanFactoryPostProcessor详解

@FunctionalInterface
public interface BeanFactoryPostProcessor {
    void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;
}

public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {
	void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
}

@Component
public class A {
}

@Component
public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		BeanDefinition beanDefinition = beanFactory.getBeanDefinition("a");
		beanDefinition.setScope("prototype");
	}
}

@Configuration
@ComponentScan("com.jame")
public class Myconfig {
}

public class MyTest {
	public static void main(String[] args)  {
		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Myconfig.class);
		A a = context.getBean(A.class);
		A a1 = context.getBean(A.class);
		System.out.println(a==a1);
    }
}

@Component
public class A {
}

public class B  {
}

@Component
public class MyBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {

	@Override
	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
		RootBeanDefinition beanDefinition = new RootBeanDefinition(B.class);
		registry.registerBeanDefinition("b",beanDefinition);
		registry.removeBeanDefinition("a");
	}

	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
	}
}

@Configuration
@ComponentScan("com.jame")
public class Myconfig {
}

public class MyTest {
	public static void main(String[] args)  {
		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Myconfig.class);
		B b = context.getBean(B.class);
		System.out.println(b);
		A a = context.getBean(A.class);
    }
}

public AnnotationConfigApplicationContext(Class<?>... componentClasses) {
   this();
   register(componentClasses);
   refresh();
}

@Override
public void refresh() throws BeansException, IllegalStateException {
......
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);
........
}
}

public static void invokeBeanFactoryPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

		Set<String> processedBeans = new HashSet<>();

		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
            
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();

			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					registryProcessors.add(registryProcessor);
				} else {
					regularPostProcessors.add(postProcessor);
				}
			}
            
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			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);
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			currentRegistryProcessors.clear();

			postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			currentRegistryProcessors.clear();
            
			boolean reiterate = true;
			while (reiterate) {
				reiterate = false;
				postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
				for (String ppName : postProcessorNames) {
					if (!processedBeans.contains(ppName)) {
						currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
						processedBeans.add(ppName);
						reiterate = true;
					}
				}
				sortPostProcessors(currentRegistryProcessors, beanFactory);
				registryProcessors.addAll(currentRegistryProcessors);
				invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
				currentRegistryProcessors.clear();
			}

			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
		} else {
			invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
		}

		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {
			if (processedBeans.contains(ppName)) {
                
			} else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
			} else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			} else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

		List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : nonOrderedPostProcessorNames) {
			nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
		beanFactory.clearMetadataCache();
	}

Set<String> processedBeans = new HashSet<>();

if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;

			//存放直接实现BeanFactoryPostProcessor,处理过/找到的实现类
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();

			//存放直接实现BeanDefinitionRegistryPostProcessor,处理过/找到的实现类
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();

			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					registryProcessors.add(registryProcessor);
				} else {
					regularPostProcessors.add(postProcessor);
				}
			}

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Myconfig.class);
context.addBeanFactoryPostProcessor(new MyBeanFactoryPostProcessor());

public AnnotationConfigApplicationContext(Class<?>... componentClasses) {
    this();   
    register(componentClasses);    
    refresh();
}

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
    context.register(Myconfig.class);
    context.addBeanFactoryPostProcessor(new MyBeanFactoryPostProcessor());
    context.refresh();

if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
    BeanDefinitionRegistryPostProcessor registryProcessor =
        (BeanDefinitionRegistryPostProcessor) postProcessor;
    registryProcessor.postProcessBeanDefinitionRegistry(registry);
    registryProcessors.add(registryProcessor);
} else {
    regularPostProcessors.add(postProcessor);
}

if (beanFactory instanceof BeanDefinitionRegistry) {
    BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;

    //存放直接实现BeanFactoryPostProcessor,处理过/找到的实现类
    List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();

    //存放直接实现BeanDefinitionRegistryPostProcessor,处理过/找到的实现类
    List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
    ......
}

List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

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);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();

public interface PriorityOrdered extends Ordered {
}

public interface Ordered {
	int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;
	int LOWEST_PRECEDENCE = Integer.MAX_VALUE;
	int getOrder();
}

currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));

//储存已经完成处理的BeanFactoryPostProcessor名字
Set<String> processedBeans = new HashSet<>();

//存放直接实现BeanDefinitionRegistryPostProcessor,处理过的实现类
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();

private static void invokeBeanDefinitionRegistryPostProcessors(
    Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
    for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
        postProcessor.postProcessBeanDefinitionRegistry(registry);
    }
}

postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
    //这里判断如果在存储已经完成的集合中没有找到当前的BeanDefinitionRegistryPostProcessor
    //也就是说明这个还没有被执行过,那么放入当前执行的集合中进行下一步操作
    if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
        currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
        processedBeans.add(ppName);
    }
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
//一样的代码,执行postProcessBeanFactory方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();

if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) 

 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));

List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

boolean reiterate = true;
while (reiterate) {
    reiterate = false;
    postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
    for (String ppName : postProcessorNames) {
        if (!processedBeans.contains(ppName)) {
            currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
            processedBeans.add(ppName);
            reiterate = true;
        }
    }
    sortPostProcessors(currentRegistryProcessors, beanFactory);
    registryProcessors.addAll(currentRegistryProcessors);
    invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
    currentRegistryProcessors.clear();
}

registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);

//为什么要传入已经执行过的BeanDefinitionRegisterPostProcess的集合?
//因为我们自定义的类实现了BeanDefinitionRegisterPostProcess这个接口
//而这个接口又继承了BeanFactoryPostProcess,那么我们不仅要实现子类的方法,还要实现父类的方法
//而在上面的处理仅仅调用了子类的方法,所以又在这里调用一次父类的方法
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);

String[] postProcessorNames =
    beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
//分别是存放实现了priorityOrdered接口,Ordered接口,和没有实现Ordered接口的名称集合
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
    if (processedBeans.contains(ppName)) {
        // skip - already processed in first phase above
    } else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
        priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
    } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
        orderedPostProcessorNames.add(ppName);
    } else {
        nonOrderedPostProcessorNames.add(ppName);
    }
}

// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
for (String postProcessorName : orderedPostProcessorNames) {
    orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

// Finally, invoke all other BeanFactoryPostProcessors.
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
for (String postProcessorName : nonOrderedPostProcessorNames) {
    nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);

public class BDRPP_API  implements BeanDefinitionRegistryPostProcessor {
	@Override
	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
		System.out.println("API-BDRPP_API的postProcessBeanDefinitionRegistry方法");
	}

	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		System.out.println("API-BDRPP_API的postProcessBeanFactory方法");
	}
}


@Component
public class BDRPP_Scan implements BeanDefinitionRegistryPostProcessor {
	@Override
	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
		System.out.println("扫描-BDRPP_Scan的postProcessBeanDefinitionRegistry方法");
	}

	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		System.out.println("扫描-BDRPP_Scan的postProcessBeanFactory方法");
	}
}



@Component
public class BFPP_Scan implements BeanFactoryPostProcessor {
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		System.out.println("扫描-BFPP_Scan类的postProcessBeanFactory方法");
	}
}

String[] postProcessorNames =    beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

public AnnotationConfigApplicationContext() {
    //spring内置的bd将在这里进行注册
    this.reader = new AnnotatedBeanDefinitionReader(this);
    this.scanner = new ClassPathBeanDefinitionScanner(this);
}

public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
    Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
    Assert.notNull(environment, "Environment must not be null");
    this.registry = registry;
    this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
    //这里
    AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}

public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
    BeanDefinitionRegistry registry, @Nullable Object source) {
    .....
        if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
            RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
            def.setSource(source);
            beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
        }
    .......
}

public static final String CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME =
    "org.springframework.context.annotation.internalConfigurationAnnotationProcessor";

@Override
public boolean containsBeanDefinition(String beanName) {
    Assert.notNull(beanName, "Bean name must not be null");
    return this.beanDefinitionMap.containsKey(beanName);
}