huifer
5 years ago
parent
8f090197cc
commit
eb28da988f
@ -0,0 +1,447 @@
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# Spring BeanFactoryPostProcessor
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [huifer-spring](https://github.com/huifer/spring-framework-read)
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- 作用: 定制或修改`BeanDefinition`的属性
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## Demo
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```java
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public class ChangeAttrBeanPostProcessor implements BeanFactoryPostProcessor {
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private Set<String> attr;
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public ChangeAttrBeanPostProcessor() {
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attr = new HashSet<>();
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}
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public Set<String> getAttr() {
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return attr;
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}
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public void setAttr(Set<String> attr) {
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this.attr = attr;
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}
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@Override
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public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
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String[] beanDefinitionNames = beanFactory.getBeanDefinitionNames();
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for (String beanName : beanDefinitionNames) {
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BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);
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StringValueResolver stringValueResolver = new StringValueResolver() {
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@Override
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public String resolveStringValue(String strVal) {
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if (attr.contains(strVal)) {
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return "隐藏属性";
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}
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else {
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return strVal;
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}
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}
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};
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BeanDefinitionVisitor visitor = new BeanDefinitionVisitor(stringValueResolver);
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visitor.visitBeanDefinition(beanDefinition);
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}
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}
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}
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```
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```java
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public class BeanFactoryPostProcessorSourceCode {
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public static void main(String[] args) {
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ApplicationContext context = new ClassPathXmlApplicationContext("BeanFactoryPostProcessor-demo.xml");
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Apple apple = context.getBean("apple", Apple.class);
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System.out.println(apple);
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}
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}
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```
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xmlns="http://www.springframework.org/schema/beans"
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xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
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<bean id="removeAttrBeanPostProcessor"
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class="com.huifer.source.spring.beanPostProcessor.ChangeAttrBeanPostProcessor">
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<property name="attr">
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<set>
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<value>hc</value>
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</set>
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</property>
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</bean>
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<bean id="apple" class="com.huifer.source.spring.bean.Apple">
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<property name="name" value="hc"/>
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</bean>
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</beans>
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```
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## 初始化
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- `org.springframework.context.support.AbstractApplicationContext#refresh`
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```JAVA
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invokeBeanFactoryPostProcessors(beanFactory);
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```
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```JAVA
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protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
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PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
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// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
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// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
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if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
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beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
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beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
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}
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}
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```
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- `org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.List<org.springframework.beans.factory.config.BeanFactoryPostProcessor>)`
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```JAVA
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public static void invokeBeanFactoryPostProcessors(
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ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
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// Invoke BeanDefinitionRegistryPostProcessors first, if any.
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Set<String> processedBeans = new HashSet<>();
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// 判断是否为BeanDefinitionRegistry类
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if (beanFactory instanceof BeanDefinitionRegistry) {
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BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
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// 存放 BeanFactoryPostProcessor
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List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
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// 存放 BeanDefinitionRegistryPostProcessor
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List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
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// 2.首先处理入参中的beanFactoryPostProcessors
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for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
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// 判断是否是BeanDefinitionRegistryPostProcessor
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if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
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BeanDefinitionRegistryPostProcessor registryProcessor =
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(BeanDefinitionRegistryPostProcessor) postProcessor;
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//
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registryProcessor.postProcessBeanDefinitionRegistry(registry);
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// BeanDefinitionRegistryPostProcessor 添加
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// 执行 postProcessBeanFactory
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registryProcessors.add(registryProcessor);
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}
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// 这部分else 内容就是 BeanFactoryPostProcessor
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else {
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// BeanFactoryPostProcessor 添加
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regularPostProcessors.add(postProcessor);
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}
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}
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// Do not initialize FactoryBeans here: We need to leave all regular beans
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// uninitialized to let the bean factory post-processors apply to them!
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// Separate between BeanDefinitionRegistryPostProcessors that implement
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// PriorityOrdered, Ordered, and the rest.
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List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
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// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
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/**
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* 调用实现{@link PriorityOrdered}\{@link BeanDefinitionRegistryPostProcessor}
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* todo: 2020年1月16日 解析方法
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* {@link DefaultListableBeanFactory#getBeanNamesForType(java.lang.Class, boolean, boolean)}
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*/
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String[] postProcessorNames =
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beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
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for (String ppName : postProcessorNames) {
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if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
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currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
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processedBeans.add(ppName);
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}
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}
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// 排序Order
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sortPostProcessors(currentRegistryProcessors, beanFactory);
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registryProcessors.addAll(currentRegistryProcessors);
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invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
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currentRegistryProcessors.clear();
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// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
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postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
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for (String ppName : postProcessorNames) {
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if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
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currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
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processedBeans.add(ppName);
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}
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}
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sortPostProcessors(currentRegistryProcessors, beanFactory);
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registryProcessors.addAll(currentRegistryProcessors);
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invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
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currentRegistryProcessors.clear();
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// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
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boolean reiterate = true;
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while (reiterate) {
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reiterate = false;
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postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
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for (String ppName : postProcessorNames) {
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if (!processedBeans.contains(ppName)) {
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currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
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processedBeans.add(ppName);
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reiterate = true;
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}
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}
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sortPostProcessors(currentRegistryProcessors, beanFactory);
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registryProcessors.addAll(currentRegistryProcessors);
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invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
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currentRegistryProcessors.clear();
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}
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// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
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invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
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invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
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} else {
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// Invoke factory processors registered with the context instance.
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invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
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}
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// Do not initialize FactoryBeans here: We need to leave all regular beans
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// uninitialized to let the bean factory post-processors apply to them!
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// 配置文件中的 BeanFactoryPostProcessor 处理
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String[] postProcessorNames =
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beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
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// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
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// Ordered, and the rest.
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List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
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List<String> orderedPostProcessorNames = new ArrayList<>();
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List<String> nonOrderedPostProcessorNames = new ArrayList<>();
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for (String ppName : postProcessorNames) {
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if (processedBeans.contains(ppName)) {
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// skip - already processed in first phase above
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// 处理过的跳过
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} else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
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priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
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} else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
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orderedPostProcessorNames.add(ppName);
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} else {
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nonOrderedPostProcessorNames.add(ppName);
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}
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}
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// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
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sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
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invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
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// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
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List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
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for (String postProcessorName : orderedPostProcessorNames) {
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orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
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}
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sortPostProcessors(orderedPostProcessors, beanFactory);
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invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
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// Finally, invoke all other BeanFactoryPostProcessors.
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// 配置文件中自定义的 BeanFactoryPostProcessor 注册
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List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
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for (String postProcessorName : nonOrderedPostProcessorNames) {
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nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
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}
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invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
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// Clear cached merged bean definitions since the post-processors might have
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// modified the original metadata, e.g. replacing placeholders in values...
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beanFactory.clearMetadataCache();
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}
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```
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## InstantiationAwareBeanPostProcessor
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```java
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protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
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PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
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}
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```
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```java
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public static void registerBeanPostProcessors(
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ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
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// 获取 BeanPostProcessor
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String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
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// Register BeanPostProcessorChecker that logs an info message when
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// a bean is created during BeanPostProcessor instantiation, i.e. when
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// a bean is not eligible for getting processed by all BeanPostProcessors.
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// 获取数量
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int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
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beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
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// Separate between BeanPostProcessors that implement PriorityOrdered,
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// Ordered, and the rest.
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// BeanPostProcessor 通过PriorityOrdered保证顺序
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List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
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// MergedBeanDefinitionPostProcessor
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List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
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// 有序的 BeanPostProcessor
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List<String> orderedPostProcessorNames = new ArrayList<>();
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// 无序的 BeanPostProcessor
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List<String> nonOrderedPostProcessorNames = new ArrayList<>();
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for (String ppName : postProcessorNames) {
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if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
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BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
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priorityOrderedPostProcessors.add(pp);
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// 类型判断放入相应的list
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if (pp instanceof MergedBeanDefinitionPostProcessor) {
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internalPostProcessors.add(pp);
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}
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}
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else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
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orderedPostProcessorNames.add(ppName);
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}
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else {
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nonOrderedPostProcessorNames.add(ppName);
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}
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}
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// First, register the BeanPostProcessors that implement PriorityOrdered.
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/**
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* 有{@link org.springframework.core.annotation.Order} 相关操作
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*/
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sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
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// 注册 BeanPostProcessor 和 PriorityOrdered 实现
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registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
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// Next, register the BeanPostProcessors that implement Ordered.
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List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
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for (String ppName : orderedPostProcessorNames) {
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BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
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orderedPostProcessors.add(pp);
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if (pp instanceof MergedBeanDefinitionPostProcessor) {
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internalPostProcessors.add(pp);
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}
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}
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sortPostProcessors(orderedPostProcessors, beanFactory);
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// 注册 实现Order 和 BeanPostProcessor
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registerBeanPostProcessors(beanFactory, orderedPostProcessors);
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// Now, register all regular BeanPostProcessors.
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List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
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for (String ppName : nonOrderedPostProcessorNames) {
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BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
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nonOrderedPostProcessors.add(pp);
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if (pp instanceof MergedBeanDefinitionPostProcessor) {
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internalPostProcessors.add(pp);
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}
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}
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// 注册无序的 BeanPostProcessor
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registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
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// Finally, re-register all internal BeanPostProcessors.
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sortPostProcessors(internalPostProcessors, beanFactory);
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// 注册 MergedBeanDefinitionPostProcessor
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registerBeanPostProcessors(beanFactory, internalPostProcessors);
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// Re-register post-processor for detecting inner beans as ApplicationListeners,
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// moving it to the end of the processor chain (for picking up proxies etc).
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// 添加 ApplicationListenerDetector
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beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
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}
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```
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- 测试用Bean
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```java
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public class DemoInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor {
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@Override
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public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
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System.out.println("init bean beanClass = " + beanClass.getSimpleName() + " beanName = " + beanName);
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return null;
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}
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}
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```
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- 按照笔者的注释,可以知道`DemoInstantiationAwareBeanPostProcessor` 这个类是一个无序Bean
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- 注册方法信息截图
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### 使用阶段(调用阶段)
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在`org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])`中有如下代码
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```JAVA
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Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
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```
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- `org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#resolveBeforeInstantiation`
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```JAVA
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@Nullable
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protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
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Object bean = null;
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if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
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// Make sure bean class is actually resolved at this point.
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if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
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Class<?> targetType = determineTargetType(beanName, mbd);
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if (targetType != null) {
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/**
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* 主要实现{@link org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation(java.lang.Class, java.lang.String)}
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*/
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bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
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if (bean != null) {
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bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
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}
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}
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}
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mbd.beforeInstantiationResolved = (bean != null);
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}
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return bean;
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}
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```
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- `org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyBeanPostProcessorsBeforeInstantiation`
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```JAVA
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@Nullable
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protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {
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for (BeanPostProcessor bp : getBeanPostProcessors()) {
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if (bp instanceof InstantiationAwareBeanPostProcessor) {
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InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
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// 调用自定义实现
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Object result = ibp.postProcessBeforeInstantiation(beanClass, beanName);
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if (result != null) {
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return result;
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}
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}
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}
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return null;
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}
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```
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这个地方已经可以看到`InstantiationAwareBeanPostProcessor`出现了,并且调用了方法`postProcessBeforeInstantiation`，此处就可以调用我们的自定义方法了
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After Width: | Height: | Size: 131 KiB |
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After Width: | Height: | Size: 42 KiB |
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After Width: | Height: | Size: 79 KiB |
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After Width: | Height: | Size: 37 KiB |
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After Width: | Height: | Size: 43 KiB |
|
After Width: | Height: | Size: 42 KiB |
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