① - 调用父类的实现
// ServletWebServerApplicationContext.java
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 添加用于处理WebApplicationContextServletContextAware接口的processor
beanFactory.addBeanPostProcessor(new WebApplicationContextServletContextAwareProcessor(this));
// 忽略ServletContextAware接口的注入
beanFactory.ignoreDependencyInterface(ServletContextAware.class);
registerWebApplicationScopes();
}
// 注册web应用的作用域
public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory,
@Nullable ServletContext sc) {
beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());
beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope());
if (sc != null) {
ServletContextScope appScope = new ServletContextScope(sc);
beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope);
// Register as ServletContext attribute, for ContextCleanupListener to detect it.
sc.setAttribute(ServletContextScope.class.getName(), appScope);
}
beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory());
beanFactory.registerResolvableDependency(ServletResponse.class, new ResponseObjectFactory());
beanFactory.registerResolvableDependency(HttpSession.class, new SessionObjectFactory());
beanFactory.registerResolvableDependency(WebRequest.class, new WebRequestObjectFactory());
if (jsfPresent) {
FacesDependencyRegistrar.registerFacesDependencies(beanFactory);
}
}
② - 根据basePackage指定的位置进行扫描bean
③ - 根据注解来扫描指定的bean
invokeBeanFactoryPostProcessors()
主要用于调用BeanFactoryPostProcessors的实现
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 调用BeanFactoryPostProcessor
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
在调用BeanFactoryPostProcessor时，会首先调用BeanDefinitionRegistryPostProcessor, 因为后者是对前者的扩展，并且有可能在后者中又重新注册了前者的其他实例。由于PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors（）方法过长，这里直接写行内注释能够比较
直观的分析前后关系。
public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
// 已处理的Bean
Set<String> processedBeans = new HashSet<>();
// 判断当前的BeanFactory是否为一个Bean注册器，实际上就是代表同时实现了BeanDefinitionRegistryPostProcessor和BeanFactoryPostProcessor接口的实现
// 对于同时实现两个接口的类，将先调用BeanDefinitionRegistryPostProcessor里面的方法，再调用BeanFactoryPostProcessor里面的方法
// 在调用的时候又要区分是实现了PriorityOrdered还是Ordered接口。
if (beanFactory instanceof BeanDefinitionRegistry) {
// 转换为注册器
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
// 用于存放常规的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
// 用于存放BeanFactoryPostProcessor的扩展BeanDefinitionRegistryPostProcessor，这里是一个汇总的列表
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
// 遍历传入的BeanFactoryPostProcessor
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
// 优先执行BeanFactoryPostProcessor的扩展类BeanDefinitionRegistryPostProcessor，它的优先级最高
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
// 类型转换
BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor;
// 调用postProcessBeanDefinitionRegistry()方法，内部可能注册了Bean，也可能重新定义了一些普通的BeanFactoryPostProcessor
registryProcessor.postProcessBeanDefinitionRegistry(registry);
// 添加到已处理列表
registryProcessors.add(registryProcessor);
}
else {
// 对比上面if代码块会发现，这里没有作调用，直接先保存在常规列表内部，因为常规的Processor在调用的时候还有其他考虑，接着往下看便是
regularPostProcessors.add(postProcessor);
}
}
// 不要在这里初始化FactoryBean（请看清是FactoryBean，工厂类，不是类工厂（BeanFactory），他们有巨大的差异），需要保留所有的常规类未初始化，以便使用BeanFactoryPostProcessor对其处理
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// 根据BeanDefinitionRegistryPostProcessors 实现的接口划分为三类：实现了PriorityOrdered的、实现了Ordered的以及前面两者都没实现的
// Separate between BeanDefinitionRegistryPostProcessors that implement
// PriorityOrdered, Ordered, and the rest.
// 保存当前将要处理的BeanDefinitionRegistryPostProcessor列表，每处理完一种分类的就清空
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// 首先调用实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessors
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 获取当前Bean工厂内部所有的，类型为BeanDefinitionRegistryPostProcessor.class的后处理器名称
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
// 筛选出实现了PriorityOrdered接口的后处理器，放入当前处理列表
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
// 同时放入已处理列表
processedBeans.add(ppName);
}
}
// 按照优先级排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
// 添加实现了PriorityOrder接口的BeanDefinitionRegistryPostProcessor到它的汇总列表里面
registryProcessors.addAll(currentRegistryProcessors);
// 调用所有的BeanDefinitionRegistryPostProcessor实例的postProcessBeanDefinitionRegistry()方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 清除内部的实现了PriorityOrder的BeanDefinitionRegistryPostProcessor
currentRegistryProcessors.clear();
// 上面是处理实现了PriorityOrdered接口的，这里处理实现了Ordered接口的, 为何这里又获取了一次postProcessorNames，前面不是才获取么？
// 这里获取一次是因为前面处理的时候有可能又加入了新的BeanDefinitionRegistryPostProcessor
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
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);
// 清空上一步已经执行过的
currentRegistryProcessors.clear();
// 继续调用普通的BeanDefinitionRegistryPostProcessors
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
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();
}
// 最后调用普通的 BeanFactoryPostProcessor，
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
//因为BeanDefinitionRegistryPostProcessor也是继承了BeanFactoryPostProcessor，，也具有postProcessBeanFactory（）方法的，所以也需要执行
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// 若不是BeanDefinitionRegistry，那就是直接实现了BeanFactoryPostProcessor
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 下面这部分逻辑就和上面套路一样，无非处理的是BeanFactoryPostProcessor罢了
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
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<>();
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);
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
beanFactory.clearMetadataCache();
}
小结
