refresh

spring-beans/src/main/java/org/springframework/beans/factory/support/BeanDefinitionRegistryPostProcessor.java

@@ -40,6 +40,10 @@ public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProc
      *
      * @param registry the bean definition registry used by the application context
      * @throws org.springframework.beans.BeansException in case of errors
+     *
+     * 在标准初始化之后修改应用程序上下文的内部 bean 定义注册表。所有常规 bean 定义都将被加载，
+     * 但尚未实例化任何 bean。这允许在下一个后处理阶段开始之前添加更多的 bean 定义。
+     * 参数：registry - 应用程序上下文使用的 bean 定义注册
      */
     void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
 

spring-beans/src/test/java/org/springframework/beans/cstest/jvm/DemoOne.java

+package org.springframework.beans.cstest.jvm;
+
+public class DemoOne {
+
+    public static void main(String[] args) {
+        String s = new String("1111");
+        String intern = s.intern();
+        System.out.println(intern);
+
+        String ss = new String("1") + new String("1");
+        String sss = "22";
+        ss.intern();
+        System.err.println(ss == sss);
+
+    }
+}

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -198,7 +198,7 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 	@Nullable
 	private ConfigurableEnvironment environment;
 
-	/** BeanFactoryPostProcessors to apply on refresh. */
+	/** BeanFactoryPostProcessors to apply on refresh. 在刷新是使用*/
 	private final List<BeanFactoryPostProcessor> beanFactoryPostProcessors = new ArrayList<>();
 
 	/** System time in milliseconds when this context started. */

spring-context/src/main/java/org/springframework/context/support/PostProcessorRegistrationDelegate.java

@@ -80,17 +80,23 @@ final class PostProcessorRegistrationDelegate {
 
 		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
 		Set<String> processedBeans = new HashSet<>();
-
+        /** 对BeanDefinitionRegistry类型的处理*/
 		if (beanFactory instanceof BeanDefinitionRegistry registry) {
 			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
+			/** BeanDefinitionRegistryPostProcessor */
 			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
 
 			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
 				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor registryProcessor) {
+					/**
+					 * 对于BeanDefinitionRegistryPostProcessor类型，在BeanFactoryPostProcessor的基础上还有
+					 * 自己定义的方法，需要先调用
+					 */
 					registryProcessor.postProcessBeanDefinitionRegistry(registry);
 					registryProcessors.add(registryProcessor);
 				}
 				else {
+					/** 记录常规 BeanFactoryPostProcessor*/
 					regularPostProcessors.add(postProcessor);
 				}
 			}
@@ -99,9 +105,17 @@ final class PostProcessorRegistrationDelegate {
 			// uninitialized to let the bean factory post-processors apply to them!
 			// Separate between BeanDefinitionRegistryPostProcessors that implement
 			// PriorityOrdered, Ordered, and the rest.
+			/**
+			 * 不要在此处初始化 FactoryBeans：我们需要让所有常规 bean 保持未初始化状态，
+			 * 以便 bean 工厂后处理器应用到它们！将实现 PriorityOrdered、Ordered 和其余部分的
+			 * BeanDefinitionRegistryPostProcessor 分开。
+			 */
 			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
 
 			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
+			/**
+			 * 首先，调用实现 PriorityOrdered 的 BeanDefinitionRegistryPostProcessor。
+			 */
 			String[] postProcessorNames =
 					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
 			for (String ppName : postProcessorNames) {
@@ -226,14 +240,23 @@ final class PostProcessorRegistrationDelegate {
 		// Register BeanPostProcessorChecker that logs an info message when
 		// a bean is created during BeanPostProcessor instantiation, i.e. when
 		// a bean is not eligible for getting processed by all BeanPostProcessors.
+		/**
+		 * BeanPostProcessorChecker 是一个普通的信息打印，可能会有些情况，
+		 * 当Spring的配置中的后处理器还没有被注册就已经开始了bean的初始化时
+		 * 便会打印出BeanPostProcessorChecker中设定的信息。
+		 */
 		int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
 		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
 
 		// Separate between BeanPostProcessors that implement PriorityOrdered,
 		// Ordered, and the rest.
+		/** 调用priorityOrdered保证排序*/
 		List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
+        /** MergedBeanDefinitionPostProcessor*/
 		List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
+		/** 使用Ordered 保证排序*/
 		List<String> orderedPostProcessorNames = new ArrayList<>();
+		/** 无序BeanPostProcessor*/
 		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
 		for (String ppName : postProcessorNames) {
 			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
@@ -252,9 +275,11 @@ final class PostProcessorRegistrationDelegate {
 		}
 
 		// First, register the BeanPostProcessors that implement PriorityOrdered.
+		/** 第 1 步，注册实现 PriorityOrdered 的 BeanPostProcessor。*/
 		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
 		registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
 
+		/** 第 2 步，注册所有实现Ordered的BeanPostProcessor*/
 		// Next, register the BeanPostProcessors that implement Ordered.
 		List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
 		for (String ppName : orderedPostProcessorNames) {
@@ -267,6 +292,7 @@ final class PostProcessorRegistrationDelegate {
 		sortPostProcessors(orderedPostProcessors, beanFactory);
 		registerBeanPostProcessors(beanFactory, orderedPostProcessors);
 
+		/** 第 3 步，注册所有无序的BeanPostProcessor*/
 		// Now, register all regular BeanPostProcessors.
 		List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
 		for (String ppName : nonOrderedPostProcessorNames) {
@@ -278,12 +304,19 @@ final class PostProcessorRegistrationDelegate {
 		}
 		registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
 
+		/**
+		 * 第 4 步，注册所有MergedBeanDefinitionPostProcessor类型的BeanPostProcessor，
+		 * 并非重复注册
+		 *
+		 * 在beanFactory.addBeanPostProcessor中会先移出已存在的BeanPostProcessor
+		 */
 		// Finally, re-register all internal BeanPostProcessors.
 		sortPostProcessors(internalPostProcessors, beanFactory);
 		registerBeanPostProcessors(beanFactory, internalPostProcessors);
 
 		// Re-register post-processor for detecting inner beans as ApplicationListeners,
 		// moving it to the end of the processor chain (for picking up proxies etc).
+		/** 添加 ApplicationListener探测器*/
 		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
 	}