一、refresh()方法之invokeBeanFactoryPostProcessors(beanFactory)方法
invokeBeanFactoryPostProcessors(beanFactory);
二、invokeBeanFactoryPostProcessors(beanFactory)方法详解
点击进入invokeBeanFactoryPostProcessors方法
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getBeanFactoryPostProcessors方法，默认该方法返回值是没有BeanFactoryPostProcessor的。
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然后，我们继续看下invokeBeanFactoryPostProcessors方法的内容：
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
//判断我们的beanFactory是否实现了BeanDefinitionRegistry
// 1.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;
//保存BeanFactoryPostProcessor类型的后置处理器
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
//保存BeanDefinitionRegistryPostProcessor类型的后置处理器
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//调用它的后置方法
registryProcessor.postProcessBeanDefinitionRegistry(registry);
//添加到我们用于保存的BeanDefinitionRegistryPostProcessor的集合中
registryProcessors.add(registryProcessor);
}
else {
//若没有实现BeanDefinitionRegistryPostProcessor接口，那么他就是BeanFactoryPostProcessor 把当前的后置处理器加入到regularPostProcessors中
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.
//定义一个集合用户保存当前准备创建的BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
//第一步:去容器中获取BeanDefinitionRegistryPostProcessor的bean的处理器名称
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
//判断是否实现了PriorityOrdered接口的
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
/**
* 在这里典型的BeanDefinitionRegistryPostProcessor就是ConfigurationClassPostProcessor
* 用于进行bean定义的加载 比如我们的包扫描，@import等
*/
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
//表示没有被处理过,且实现了Ordered接口的
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();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//调用没有实现任何优先级接口的BeanDefinitionRegistryPostProcessor
//定义一个重复处理的开关变量 默认值为true
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);
//遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
//调用实现了BeanDefinitionRegistryPostProcessor的接口 它同时实现了BeanFactoryPostProcessor的方法
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
//调用BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
//最后一步 获取容器中所有的 BeanFactoryPostProcessor
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
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<>(orderedPostProcessorNames.size());
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<>(nonOrderedPostProcessorNames.size());
for (String postProcessorName : nonOrderedPostProcessorNames) {
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
beanFactory.clearMetadataCache();
}
该方法内容虽多，但还是很好理解的。
- 整个 invokeBeanFactoryPostProcessors 方法围绕两个接口，BeanDefinitionRegistryPostProcessor 和 BeanFactoryPostProcessor，其中 BeanDefinitionRegistryPostProcessor 继承了 BeanFactoryPostProcessor。
public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {
void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
}
BeanDefinitionRegistryPostProcessor 主要用来在常规 BeanFactoryPostProcessor 检测开始之前注册其他 Bean 定义，说的简单点，就是 BeanDefinitionRegistryPostProcessor 具有更高的优先级，执行顺序在 BeanFactoryPostProcessor 之前。
- 操作3种 bean 对象具体指的是调用它们重写的方法，调用实现方法时会遵循以下的优先级：
第一优先级：入参 beanFactoryPostProcessors 中的 BeanDefinitionRegistryPostProcessor， 调用 postProcessBeanDefinitionRegistry 方法。
第二优先级：BeanDefinitionRegistryPostProcessor 接口实现类，并且实现了 PriorityOrdered 接口，调用 postProcessBeanDefinitionRegistry 方法。
第三优先级：BeanDefinitionRegistryPostProcessor 接口实现类，并且实现了 Ordered 接口，调用 postProcessBeanDefinitionRegistry 方法。
第四优先级：除去第二优先级和第三优先级，剩余的 BeanDefinitionRegistryPostProcessor 接口实现类，调用 postProcessBeanDefinitionRegistry 方法。
第五优先级：所有 BeanDefinitionRegistryPostProcessor 接口实现类，调用 postProcessBeanFactory 方法。
第六优先级：入参 beanFactoryPostProcessors 中的常规 BeanFactoryPostProcessor，调用 postProcessBeanFactory 方法。
第七优先级：常规 BeanFactoryPostProcessor 接口实现类，并且实现了 PriorityOrdered 接口，调用 postProcessBeanFactory 方法。
第八优先级：常规 BeanFactoryPostProcessor 接口实现类，并且实现了 Ordered 接口，调用 postProcessBeanFactory 方法。
第九优先级：除去第七优先级和第八优先级，剩余的常规 BeanFactoryPostProcessor 接口的实现类，调用 postProcessBeanFactory 方。
- 本文还引入了两个用于排序的重要接口：PriorityOrdered 和 Ordered，其中 PriorityOrdered 继承了 Ordered，并且 PriorityOrdered 的优先级要高于 Ordered，这跟 BeanDefinitionRegistryPostProcessor 继承 BeanFactoryPostProcessor 有点类似。实现 Ordered 接口需要重写 getOrder 方法，返回一个用于排序的 order 值，order 值的范围为 Integer.MIN_VALUE ~ Integer.MAX_VALUE，order 值越小优先级越高，Integer.MIN_VALUE 拥有最高优先级，而 Integer.MAX_VALUE 则对应的拥有最低优先级。
三、自定义扩展BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor接口测试
CustomBeanFactoryPostProcessor类：
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.core.Ordered;
public class CustomBeanFactoryPostProcessor implements BeanFactoryPostProcessor, Ordered {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("This is my CustomBeanFactoryPostProcessor postProcessBeanFactory() test");
}
@Override
public int getOrder() {
return 2;
}
}
CustomBeanDefinitionRegistryPostProcessor
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.core.PriorityOrdered;
public class CustomBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor, PriorityOrdered {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("This is my CustomBeanDefinitionRegistryPostProcessor postProcessBeanFactory() test");
}
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
System.out.println(
"This is my CustomBeanDefinitionRegistryPostProcessor postProcessBeanDefinitionRegistry() test");
}
@Override
public int getOrder() {
return 3;
}
}
xml多加一些bean的配置
<bean id="customBeanDefinitionRegistryPostProcessor"
class="com.zcs.mytest.xmlSetter.CustomBeanDefinitionRegistryPostProcessor">
</bean>
<bean id="customBeanFactoryPostProcessor"
class="com.zcs.mytest.xmlSetter.CustomBeanFactoryPostProcessor">
</bean>
最后的测试结果如下：
image.png
因此，我们可以自定义扩展类来实现自定义的功能。
四、总结
至此，invokeBeanFactoryPostProcessors方法源码调试完毕。不足之处，敬请谅解！！！
