Spring源码情操陶冶-AbstractApplicationContext#invokeBeanFactoryPostProcessors

时间:2022-01-08 22:38:28
Spring源码情操陶冶-AbstractApplicationContext#invokeBeanFactoryPostProcessors

阅读源码有利于陶冶情操,承接前文Spring源码情操陶冶-AbstractApplicationContext#postProcessBeanFactory

约定:web.xml中配置的contextClassXmlWebApplicationContext

瞧瞧官方注释

	/**
* Instantiate and invoke all registered BeanFactoryPostProcessor beans,
* respecting explicit order if given.
* <p>Must be called before singleton instantiation.必须在单例实例化前调用
*/

主要是实例化和调用所有已注册的BeanFactoryPostProcessors beans

源码简析

对应的代码清单如下

	//通过一个委托类来处理实例化调用
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
}

PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors

简单的看下委托类中的此方法源码,代码清单如下

public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { // 第一步,Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<String>();
//条件满足
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
List<BeanDefinitionRegistryPostProcessor> registryPostProcessors =
new LinkedList<BeanDefinitionRegistryPostProcessor>();
//刚开始进来beanFactoryPostProcessors为空
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//BeanDefinitionRegistryPostProcessor目前该接口的实现者为MapperScannerConfigurer/ConfigurationClassPostProcessor
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryPostProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//调用postProcessBeanDefinitionRegistry接口,比如MapperScannerConfigurer则会进行扫描注册接口bean操作
registryPostProcessor.postProcessBeanDefinitionRegistry(registry);
registryPostProcessors.add(registryPostProcessor);
}
else {
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.
//寻找实现了BeanDefinitionRegistryPostProcessor接口类的beans
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.这里只有ConfigurationClassPostProcessor类才操作
List<BeanDefinitionRegistryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
***
省略部分代码
*** // Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
} else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
} //第二步,处理注册在bean工厂中BeanFactoryPostProcessor接口实现类并调用公用的方法,比如PropertyResourceConfigurer资源文件解析类
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest. 执行的优先权
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
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);
}
} ***
省略部分代码
***
}

主要功能是对实现BeanFactoryPostProcessor的bean类进行调用公共接口方法postProcessBeanFactory,并相关的信息可关联至ConfigurableListableBeanFactorybeanFactory。常见的使用类为PropertyPlaceholderConfigurer文件解析类、MapperScannerConfigurer SQL接口注册类。公共接口的调用前者会对每个bean对象含有${}进行解析替换,后者会注册mapper class接口类并尝试解析注解

下节预告

Spring源码情操陶冶-AbstractApplicationContext#registerBeanPostProcessors