Spring invokeBeanFactoryPostProcessors source
An overview of the
InvokeBeanFactoryPostProcessors method mainly processing BeanDefinitionRegistryPostProcessor and spring BeanFactoryPostProcessor, BeanDefinitionRegistryPostProcessor spring BeanFactoryPostProcessor as part of the interface, has more powerful function. These two interfaces are an important extension point for Spring before it is initialized.
InvokeBeanFactoryPostProcessors source code analysis
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<String>();
// 判断beanFactory是否为BeanDefinitionRegistry，beanFactory为DefaultListableBeanFactory,
// 而DefaultListableBeanFactory实现了BeanDefinitionRegistry接口，因此这边为true
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
// 用于存放普通的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
// 用于存放BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>();
// 首先处理入参中的beanFactoryPostProcessors
// 遍历所有的beanFactoryPostProcessors, 将BeanDefinitionRegistryPostProcessor和普通BeanFactoryPostProcessor区分开
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
// 如果是BeanDefinitionRegistryPostProcessor
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
// 直接执行BeanDefinitionRegistryPostProcessor接口的postProcessBeanDefinitionRegistry方法
registryProcessor.postProcessBeanDefinitionRegistry(registry); //@3
// 添加到registryProcessors(用于最后执行postProcessBeanFactory方法)
registryProcessors.add(registryProcessor);
} else {
// 否则，只是普通的BeanFactoryPostProcessor
// 添加到regularPostProcessors(用于最后执行postProcessBeanFactory方法)
regularPostProcessors.add(postProcessor);
}
}
// 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.
// 用于保存本次要执行的BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 调用所有实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor实现类
// 找出所有实现BeanDefinitionRegistryPostProcessor接口的Bean的beanName
//@1
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//遍历postProcessorNames
for (String ppName : postProcessorNames) {
// 校验是否实现了PriorityOrdered接口
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
// 获取ppName对应的bean实例, 添加到currentRegistryProcessors中,
// beanFactory.getBean: 这边getBean方法会触发创建ppName对应的bean对象, 目前暂不深入解析
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
// 将要被执行的加入processedBeans，避免后续重复执行
processedBeans.add(ppName);
}
}
//进行排序(根据是否实现PriorityOrdered、Ordered接口和order值来排序)
sortPostProcessors(currentRegistryProcessors, beanFactory);
// 添加到registryProcessors(用于最后执行postProcessBeanFactory方法)
registryProcessors.addAll(currentRegistryProcessors);
// 遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 执行完毕后, 清空currentRegistryProcessors
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 调用所有实现了Ordered接口的BeanDefinitionRegistryPostProcessor实现类（过程跟上面的步骤3基本一样）
// 找出所有实现BeanDefinitionRegistryPostProcessor接口的类, 这边重复查找是因为执行完上面的BeanDefinitionRegistryPostProcessor,
// 可能会新增了其他的BeanDefinitionRegistryPostProcessor, 因此需要重新查找
// @2
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
// 校验是否实现了Ordered接口，并且还未执行过
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);
// 遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后, 调用所有剩下的BeanDefinitionRegistryPostProcessors
boolean reiterate = true;
while (reiterate) {
reiterate = false;
// 找出所有实现BeanDefinitionRegistryPostProcessor接口的类
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
// 跳过已经执行过的
if (!processedBeans.contains(ppName)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
// 如果有BeanDefinitionRegistryPostProcessor被执行, 则有可能会产生新的BeanDefinitionRegistryPostProcessor,
// 因此这边将reiterate赋值为true, 代表需要再循环查找一次
reiterate = true;
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// 遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
//调用所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法(BeanDefinitionRegistryPostProcessor继承自BeanFactoryPostProcessor)
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
// 最后, 调用入参beanFactoryPostProcessors中的普通BeanFactoryPostProcessor的postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
} else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 到这里 , 入参beanFactoryPostProcessors和容器中的所有BeanDefinitionRegistryPostProcessor已经全部处理完毕,
// 下面开始处理容器中的所有BeanFactoryPostProcessor
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// 找出所有实现BeanFactoryPostProcessor接口的类
//@3
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
// 用于存放实现了PriorityOrdered接口的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
// 用于存放实现了Ordered接口的BeanFactoryPostProcessor的beanName
List<String> orderedPostProcessorNames = new ArrayList<String>();
// 用于存放普通BeanFactoryPostProcessor的beanName
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
// 遍历postProcessorNames, 将BeanFactoryPostProcessor按实现PriorityOrdered、实现Ordered接口、普通三种区分开
for (String ppName : postProcessorNames) {
// 跳过已经执行过的
if (processedBeans.contains(ppName)) {
// skip - already processed in first phase above
} else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
// 添加实现了PriorityOrdered接口的BeanFactoryPostProcessor
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
} else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
// 添加实现了Ordered接口的BeanFactoryPostProcessor的beanName
orderedPostProcessorNames.add(ppName);
} else {
// 添加剩下的普通BeanFactoryPostProcessor的beanName
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
// 调用所有实现PriorityOrdered接口的BeanFactoryPostProcessor
// 对priorityOrderedPostProcessors排序
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
// 遍历priorityOrderedPostProcessors, 执行postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
// 调用所有实现Ordered接口的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : orderedPostProcessorNames) {
// 获取postProcessorName对应的bean实例, 添加到orderedPostProcessors, 准备执行
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
// 对orderedPostProcessors排序
sortPostProcessors(orderedPostProcessors, beanFactory);
// 遍历orderedPostProcessors, 执行postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
// 调用所有剩下的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : nonOrderedPostProcessorNames) {
// 11.1 获取postProcessorName对应的bean实例, 添加到nonOrderedPostProcessors, 准备执行
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
// 遍历nonOrderedPostProcessors, 执行postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
// 清除元数据缓存（mergedBeanDefinitions、allBeanNamesByType、singletonBeanNamesByType），
// 因为后处理器可能已经修改了原始元数据，例如， 替换值中的占位符...
beanFactory.clearMetadataCache();
}@ 1 will be here we can see the beanFactory in only seven beanDefinition, is only ConfigurationClassPostProcessor BeanDefinitionRegistryPostProcessor interface is realized
So it’s going to be prioritized.
Rear ConfigurationClassPostProcessor processor is in the run () – > createApplicationContext () – > ApplicationContextFactory. The create () — – >
AnnotationConfigApplicationContext—->AnnotatedBeanDefinitionReader()—>
AnnotationConfigUtils. RegisterAnnotationConfigProcessors () to add the default processor.
@ 2 due to load the ConfigurationClassPostProcessor, system may add some implements BeanDefinitionRegistryPostProcessor class, for they sort, Traverse the execution postProcessBeanDefinitionRegistry method.
@3 loads all BeanFactoryPostProcessor implementations and executes the PostProcessBeanFactory method
From the order of the code execution can also know BeanDefinitionRegistryPostProcessor is before spring BeanFactoryPostProcessor implementation
The test demonstrates
@Component public class BeanDefinitionRegistryPostProcessorOrder1 implements BeanDefinitionRegistryPostProcessor, Ordered { @Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder1:::"+"postProcessBeanDefinitionRegistry"); } @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder1:::"+"postProcessBeanFactory"); } @Override public int getOrder() { return 1; } } @Component public class BeanDefinitionRegistryPostProcessorOrder2 implements BeanDefinitionRegistryPostProcessor, Ordered { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder2:::" + "postProcessBeanFactory"); } @Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder2:::" + "postProcessBeanDefinitionRegistry"); } @Override public int getOrder() { return 2; } } @Component public class BeanFactoryPostProcessorOrder1 implements BeanFactoryPostProcessor, Ordered { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanFactoryPostProcessorOrder1:::"+"postProcessBeanFactory"); } @Override public int getOrder() { return 1; } } @Component public class BeanFactoryPostProcessorOrder2 implements BeanFactoryPostProcessor, Ordered { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanFactoryPostProcessorOrder2:::" + "postProcessBeanFactory"); } @Override public int getOrder() { return 2; }} Output results: BeanDefinitionRegistryPostProcessorOrder1:::postProcessBeanDefinitionRegistry BeanDefinitionRegistryPostProcessorOrder2:::postProcessBeanDefinitionRegistry BeanDefinitionRegistryPostProcessorOrder1:::postProcessBeanFactory BeanDefinitionRegistryPostProcessorOrder2:::postProcessBeanFactory BeanFactoryPostProcessorOrder1:::postProcessBeanFactory BeanFactoryPostProcessorOrder2:::postProcessBeanFactory