Spring源码之invokeBeanFactoryPostProcessors
概述
invokeBeanFactoryPostProcessors方法中主要是处理BeanDefinitionRegistryPostProcessor和BeanFactoryPostProcessor，
BeanDefinitionRegistryPostProcessor是BeanFactoryPostProcessor的子接口，具有更强大的功能。这两个接口是Spring再初始化前
一个重要的扩展点。
invokeBeanFactoryPostProcessors源码分析
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这里会我们可以看下beanFactory中只有7个beanDefinition，其中只有ConfigurationClassPostProcessor是实现了BeanDefinitionRegistryPostProcessor接口
所以它会被优先执行。
ConfigurationClassPostProcessor后置处理器是在run()--->createApplicationContext()--->ApplicationContextFactory.create()--->
AnnotationConfigApplicationContext---->AnnotatedBeanDefinitionReader()--->
AnnotationConfigUtils.registerAnnotationConfigProcessors()添加的默认处理器。
@2由于加载了ConfigurationClassPostProcessor，系统中可能新增一些实现了BeanDefinitionRegistryPostProcessor的类，对他们进行排序，遍历执行postProcessBeanDefinitionRegistry方法。
@3加载所有实现了BeanFactoryPostProcessor，执行postProcessBeanFactory方法
从代码执行的顺序也可以知道BeanDefinitionRegistryPostProcessor是在BeanFactoryPostProcessor之前执行
测试论证
@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;
}
}
输出结果：
BeanDefinitionRegistryPostProcessorOrder1:::postProcessBeanDefinitionRegistry
BeanDefinitionRegistryPostProcessorOrder2:::postProcessBeanDefinitionRegistry
BeanDefinitionRegistryPostProcessorOrder1:::postProcessBeanFactory
BeanDefinitionRegistryPostProcessorOrder2:::postProcessBeanFactory
BeanFactoryPostProcessorOrder1:::postProcessBeanFactory
BeanFactoryPostProcessorOrder2:::postProcessBeanFactory实战
mybatis的@Mapper注解，dubbo的@Reference，@Service注解这些都不是Spring的注解,都是各个框架自定义的注解。
但是他们这些注解还是可以将目标对象交由Spring去管理呢。这里就可以用BeanDefinitionRegistryPostProcessor来将我们自定义的转化
为BeanDefinition。这个也符合官方的建议:**BeanDefinitionRegistryPostProcessor用来添加BeanDefinition,BeanFactoryPostProcessor用于修改BeanDefinition。
BeanDefinitionRegistryPostProcessor优先于BeanFactoryPostProcessor执行**"
先定义下注解
/**
* 自定义注解
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DefinitionAnno {
}需要被扫描的bean
@DefinitionAnno
public class DefinitionBean1 {
}
@DefinitionAnno
public class DefinitionBean2 {
}
http://git.yijiupidev.com:81/payhub/payhub-channel-protocol.git自定义注解扫描器
/**
* 注解扫描器
*/
public class DefinitionAnnoScanner extends ClassPathBeanDefinitionScanner {
private Class<? extends Annotation> annotationClass;
public void setAnnotationClass(Class<? extends Annotation> annotationClass) {
this.annotationClass = annotationClass;
}
public DefinitionAnnoScanner(BeanDefinitionRegistry registry) {
super(registry, false);
}
@Override
public Set<BeanDefinitionHolder> doScan(String... basePackages) {
Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
return beanDefinitions;
}
/**
* 添加需要扫描的注解
*/
public void registerFilters() {
if (this.annotationClass != null) {
addIncludeFilter(new AnnotationTypeFilter(this.annotationClass));
}
}
}
通过继承ClassPathBeanDefinitionScanner，添加需要被扫描的条件。这个后面会细聊，就不在这里做过多的解释了。
@Component
public class MyDefinitionPostprocessor implements BeanDefinitionRegistryPostProcessor, ApplicationContextAware {
private ApplicationContext applicationContext;
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
List<String> packages = AutoConfigurationPackages.get(this.applicationContext);
DefinitionAnnoScanner scanner = new DefinitionAnnoScanner(registry);
scanner.setAnnotationClass(DefinitionAnno.class);
scanner.registerFilters();
scanner.doScan(StringUtils.toStringArray(packages));
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
}添加MyDefinitionPostprocessor后置处理去扫描自定义的注解,这样就可以将标记的注解解析为beanDefinition,将对象交由spring管理。
结果：
java
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