Spring BeanFactoryPostProcessor

Demo

  1. public class ChangeAttrBeanPostProcessor implements BeanFactoryPostProcessor {
  2.     private Set<String> attr;
  4.     public ChangeAttrBeanPostProcessor() {
  5.         attr = new HashSet<>();
  6.     }
  8.     public Set<String> getAttr() {
  9.         return attr;
  10.     }
  12.     public void setAttr(Set<String> attr) {
  13.         this.attr = attr;
  14.     }
  16.     @Override
  17.     public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
  18.         String[] beanDefinitionNames = beanFactory.getBeanDefinitionNames();
  19.         for (String beanName : beanDefinitionNames) {
  20.             BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);
  22.             StringValueResolver stringValueResolver = new StringValueResolver() {
  23.                 @Override
  24.                 public String resolveStringValue(String strVal) {
  25.                     if (attr.contains(strVal)) {
  26.                         return "隐藏属性";
  27.                     }
  28.                     else {
  29.                         return strVal;
  30.                     }
  31.                 }
  32.             };
  33.             BeanDefinitionVisitor visitor = new BeanDefinitionVisitor(stringValueResolver);
  34.             visitor.visitBeanDefinition(beanDefinition);
  35.         }
  36.     }
  37. }
  1. public class BeanFactoryPostProcessorSourceCode {
  2.     public static void main(String[] args) {
  3.         ApplicationContext context = new ClassPathXmlApplicationContext("BeanFactoryPostProcessor-demo.xml");
  4.         Apple apple = context.getBean("apple", Apple.class);
  5.         System.out.println(apple);
  6.     }
  7. }
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3.        xmlns="http://www.springframework.org/schema/beans"
  4.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
  5.     <bean id="removeAttrBeanPostProcessor"
  6.           class="com.huifer.source.spring.beanPostProcessor.ChangeAttrBeanPostProcessor">
  7.         <property name="attr">
  8.             <set>
  9.                 <value>hc</value>
  10.             </set>
  11.         </property>
  12.     </bean>
  14.     <bean id="apple" class="com.huifer.source.spring.bean.Apple">
  15.         <property name="name" value="hc"/>
  16.     </bean>
  17. </beans>

初始化

  • org.springframework.context.support.AbstractApplicationContext#refresh

    1. invokeBeanFactoryPostProcessors(beanFactory);
    1.     protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
    2.         PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
    4.         // Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
    5.         // (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
    6.         if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
    7.             beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
    8.             beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
    9.         }
    10.     }

  • org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.List<org.springframework.beans.factory.config.BeanFactoryPostProcessor>)

    1. public static void invokeBeanFactoryPostProcessors(
    2.             ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
    4.         // Invoke BeanDefinitionRegistryPostProcessors first, if any.
    5.         Set<String> processedBeans = new HashSet<>();
    6.         // 判断是否为BeanDefinitionRegistry类
    7.         if (beanFactory instanceof BeanDefinitionRegistry) {
    8.             BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
    9.             // 存放 BeanFactoryPostProcessor
    10.             List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
    11.             // 存放 BeanDefinitionRegistryPostProcessor
    12.             List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
    14.             // 2.首先处理入参中的beanFactoryPostProcessors
    15.             for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
    16.                 // 判断是否是BeanDefinitionRegistryPostProcessor
    17.                 if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
    18.                     BeanDefinitionRegistryPostProcessor registryProcessor =
    19.                             (BeanDefinitionRegistryPostProcessor) postProcessor;
    20.                     //
    21.                     registryProcessor.postProcessBeanDefinitionRegistry(registry);
    22.                     // BeanDefinitionRegistryPostProcessor 添加
    23.                     // 执行 postProcessBeanFactory
    24.                     registryProcessors.add(registryProcessor);
    25.                 }
    26.                 // 这部分else 内容就是 BeanFactoryPostProcessor
    27.                 else {
    28.                     // BeanFactoryPostProcessor 添加
    29.                     regularPostProcessors.add(postProcessor);
    30.                 }
    31.             }
    33.             // Do not initialize FactoryBeans here: We need to leave all regular beans
    34.             // uninitialized to let the bean factory post-processors apply to them!
    35.             // Separate between BeanDefinitionRegistryPostProcessors that implement
    36.             // PriorityOrdered, Ordered, and the rest.
    37.             List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
    39.             // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
    40.             /**
    41.              * 调用实现{@link PriorityOrdered}\{@link BeanDefinitionRegistryPostProcessor}
    42.              * todo: 2020年1月16日 解析方法
    43.              *  {@link DefaultListableBeanFactory#getBeanNamesForType(java.lang.Class, boolean, boolean)}
    44.              */
    45.             String[] postProcessorNames =
    46.                     beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
    47.             for (String ppName : postProcessorNames) {
    48.                 if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
    49.                     currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
    50.                     processedBeans.add(ppName);
    51.                 }
    52.             }
    53.             // 排序Order
    54.             sortPostProcessors(currentRegistryProcessors, beanFactory);
    55.             registryProcessors.addAll(currentRegistryProcessors);
    56.             invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
    57.             currentRegistryProcessors.clear();
    59.             // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
    60.             postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
    61.             for (String ppName : postProcessorNames) {
    62.                 if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
    63.                     currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
    64.                     processedBeans.add(ppName);
    65.                 }
    66.             }
    67.             sortPostProcessors(currentRegistryProcessors, beanFactory);
    68.             registryProcessors.addAll(currentRegistryProcessors);
    69.             invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
    70.             currentRegistryProcessors.clear();
    72.             // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
    73.             boolean reiterate = true;
    74.             while (reiterate) {
    75.                 reiterate = false;
    76.                 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
    77.                 for (String ppName : postProcessorNames) {
    78.                     if (!processedBeans.contains(ppName)) {
    79.                         currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
    80.                         processedBeans.add(ppName);
    81.                         reiterate = true;
    82.                     }
    83.                 }
    84.                 sortPostProcessors(currentRegistryProcessors, beanFactory);
    85.                 registryProcessors.addAll(currentRegistryProcessors);
    86.                 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
    87.                 currentRegistryProcessors.clear();
    88.             }
    90.             // Now, invoke the postProcessBeanFactory callback of all processors handled so far.
    91.             invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
    92.             invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
    93.         } else {
    94.             // Invoke factory processors registered with the context instance.
    95.             invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
    96.         }
    98.         // Do not initialize FactoryBeans here: We need to leave all regular beans
    99.         // uninitialized to let the bean factory post-processors apply to them!
    100.         // 配置文件中的 BeanFactoryPostProcessor 处理
    101.         String[] postProcessorNames =
    102.                 beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
    104.         // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
    105.         // Ordered, and the rest.
    106.         List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
    107.         List<String> orderedPostProcessorNames = new ArrayList<>();
    108.         List<String> nonOrderedPostProcessorNames = new ArrayList<>();
    109.         for (String ppName : postProcessorNames) {
    110.             if (processedBeans.contains(ppName)) {
    111.                 // skip - already processed in first phase above
    112.                 // 处理过的跳过
    113.             } else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
    114.                 priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
    115.             } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
    116.                 orderedPostProcessorNames.add(ppName);
    117.             } else {
    118.                 nonOrderedPostProcessorNames.add(ppName);
    119.             }
    120.         }
    122.         // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
    123.         sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
    124.         invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
    126.         // Next, invoke the BeanFactoryPostProcessors that implement Ordered.
    127.         List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
    128.         for (String postProcessorName : orderedPostProcessorNames) {
    129.             orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
    130.         }
    131.         sortPostProcessors(orderedPostProcessors, beanFactory);
    132.         invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
    134.         // Finally, invoke all other BeanFactoryPostProcessors.
    135.         // 配置文件中自定义的 BeanFactoryPostProcessor 注册
    136.         List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
    137.         for (String postProcessorName : nonOrderedPostProcessorNames) {
    138.             nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
    139.         }
    140.         invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
    142.         // Clear cached merged bean definitions since the post-processors might have
    143.         // modified the original metadata, e.g. replacing placeholders in values...
    144.         beanFactory.clearMetadataCache();
    145.     }

image-20200119085346675

image-20200119085655734

InstantiationAwareBeanPostProcessor

  1.     protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
  2.         PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
  3.     }
  1.     public static void registerBeanPostProcessors(
  2.             ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
  3.         // 获取 BeanPostProcessor
  4.         String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
  6.         // Register BeanPostProcessorChecker that logs an info message when
  7.         // a bean is created during BeanPostProcessor instantiation, i.e. when
  8.         // a bean is not eligible for getting processed by all BeanPostProcessors.
  9.         // 获取数量
  10.         int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
  11.         beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
  13.         // Separate between BeanPostProcessors that implement PriorityOrdered,
  14.         // Ordered, and the rest.
  15.         // BeanPostProcessor 通过PriorityOrdered保证顺序
  16.         List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
  17.         // MergedBeanDefinitionPostProcessor
  18.         List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
  19.         // 有序的 BeanPostProcessor
  20.         List<String> orderedPostProcessorNames = new ArrayList<>();
  21.         // 无序的 BeanPostProcessor
  22.         List<String> nonOrderedPostProcessorNames = new ArrayList<>();
  23.         for (String ppName : postProcessorNames) {
  24.             if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
  25.                 BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
  26.                 priorityOrderedPostProcessors.add(pp);
  27.                 // 类型判断放入相应的list
  28.                 if (pp instanceof MergedBeanDefinitionPostProcessor) {
  29.                     internalPostProcessors.add(pp);
  30.                 }
  31.             }
  32.             else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
  33.                 orderedPostProcessorNames.add(ppName);
  34.             }
  35.             else {
  36.                 nonOrderedPostProcessorNames.add(ppName);
  37.             }
  38.         }
  40.         // First, register the BeanPostProcessors that implement PriorityOrdered.
  41.         /**
  42.          * 有{@link org.springframework.core.annotation.Order} 相关操作
  43.          */
  44.         sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
  45.         // 注册 BeanPostProcessor 和 PriorityOrdered 实现
  46.         registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
  48.         // Next, register the BeanPostProcessors that implement Ordered.
  49.         List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
  50.         for (String ppName : orderedPostProcessorNames) {
  51.             BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
  52.             orderedPostProcessors.add(pp);
  53.             if (pp instanceof MergedBeanDefinitionPostProcessor) {
  54.                 internalPostProcessors.add(pp);
  55.             }
  56.         }
  57.         sortPostProcessors(orderedPostProcessors, beanFactory);
  58.         // 注册 实现Order 和 BeanPostProcessor
  59.         registerBeanPostProcessors(beanFactory, orderedPostProcessors);
  61.         // Now, register all regular BeanPostProcessors.
  62.         List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
  63.         for (String ppName : nonOrderedPostProcessorNames) {
  64.             BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
  65.             nonOrderedPostProcessors.add(pp);
  66.             if (pp instanceof MergedBeanDefinitionPostProcessor) {
  67.                 internalPostProcessors.add(pp);
  68.             }
  69.         }
  70.         // 注册无序的 BeanPostProcessor
  71.         registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
  73.         // Finally, re-register all internal BeanPostProcessors.
  74.         sortPostProcessors(internalPostProcessors, beanFactory);
  75.         // 注册 MergedBeanDefinitionPostProcessor
  76.         registerBeanPostProcessors(beanFactory, internalPostProcessors);
  78.         // Re-register post-processor for detecting inner beans as ApplicationListeners,
  79.         // moving it to the end of the processor chain (for picking up proxies etc).
  80.         // 添加 ApplicationListenerDetector
  81.         beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
  82.     }
  • 测试用 Bean
  1. public class DemoInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor {
  2.     @Override
  3.     public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
  4.         System.out.println("init bean beanClass = " + beanClass.getSimpleName() + " beanName = " + beanName);
  5.         return null;
  6.     }
  7. }
  • 按照笔者的注释,可以知道DemoInstantiationAwareBeanPostProcessor 这个类是一个无序 Bean

image-20200119101026726

image-20200119101017989

  • 注册方法信息截图

image-20200119101107820

使用阶段(调用阶段)

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

  1.             Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
  • org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#resolveBeforeInstantiation
  1. @Nullable
  2.     protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
  3.         Object bean = null;
  4.         if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
  5.             // Make sure bean class is actually resolved at this point.
  6.             if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
  7.                 Class<?> targetType = determineTargetType(beanName, mbd);
  8.                 if (targetType != null) {
  9.                     /**
  10.                      * 主要实现{@link org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation(java.lang.Class, java.lang.String)}
  11.                      */
  12.                     bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
  13.                     if (bean != null) {
  14.                         bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
  15.                     }
  16.                 }
  17.             }
  18.             mbd.beforeInstantiationResolved = (bean != null);
  19.         }
  20.         return bean;
  21.     }
  • org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyBeanPostProcessorsBeforeInstantiation
  1.     @Nullable
  2.     protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {
  3.         for (BeanPostProcessor bp : getBeanPostProcessors()) {
  4.             if (bp instanceof InstantiationAwareBeanPostProcessor) {
  5.                 InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
  6.                 // 调用自定义实现
  7.                 Object result = ibp.postProcessBeforeInstantiation(beanClass, beanName);
  8.                 if (result != null) {
  9.                     return result;
  10.                 }
  11.             }
  12.         }
  13.         return null;
  14.     }

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

image-20200119101516591