【Spring源码解析】BeanFactoryPostProcessor【相关类】源码解析

1 BeanFactoryPostProcessor作用public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {/*** 可以修改容器Bean内部的定义信息，全部的bean definitions会加载但是bean没有被实例化*/void po...

响彻天堂丶

3870人浏览 · 2020-03-04 02:04:31

响彻天堂丶 · 2020-03-04 02:04:31 发布

1 BeanFactoryPostProcessor作用

public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {
   /**
    * 可以修改容器Bean内部的定义信息，全部的bean definitions会加载但是bean没有被实例化
    */
   void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
}

1.1 代码

(1) Student

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {

    private String name;

}

(2) 配置文件

@ComponentScan("com.spring")
@Configuration
public class SpringConfig {
    @Primary
    @Bean
    public Student zhangsan(){
        return new Student("张三");
    }
    @Bean
    public Student lisi(){
        return new Student("李四");
    }
}

(3) 主程序

public class SpringApplicationContext {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        Student bean = context.getBean(Student.class);
        System.out.println(bean.getName());
    }
}

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1.2 添加配置文件

@Configuration
public class ZrsBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        System.out.println("###############postProcessBeanFactory#################");
        System.out.println("bean 的数量为："+beanFactory.getBeanDefinitionCount());
        String[] beanDefinitionNames = beanFactory.getBeanDefinitionNames();
        System.out.println("BeanName为："+ Arrays.asList(beanDefinitionNames));
        //把李四设置成Primary
        BeanDefinition lisi = beanFactory.getBeanDefinition("lisi");
        lisi.setPrimary(true);
        //把张三设置成非Primary
        BeanDefinition zhangsan = beanFactory.getBeanDefinition("zhangsan");
        zhangsan.setPrimary(false);
    }
}

运行主程序：
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2 BeanDefinitionRegistryPostProcessor

2.1 类图

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2.2 源代码

public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {
   /**
    * BeanDefinitionRegistryPostProcessor扩充了BeanFactoryPostProcessor功能
    * BeanDefinitionRegistry可以给工厂中注册Bean
    */
   void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
}

2.3 代码

(1) 配置文件

@ComponentScan("com.spring")
@Configuration
public class SpringConfig {

}

(2) pojo

@Data
public class HelloWorld {

}

(3) ZrsBeanDefinitionRegistryPostProcessor

@Configuration
public class ZrsBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {
    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        System.out.println("postProcessBeanDefinitionRegistry：");
        System.out.println("bean 的数量为："+registry.getBeanDefinitionCount());
        RootBeanDefinition rootBeanDefinition=new RootBeanDefinition(HelloWorld.class);
        registry.registerBeanDefinition("helloworld", rootBeanDefinition);
    }
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        System.out.println("postProcessBeanFactory：");
        System.out.println("bean 的数量为："+beanFactory.getBeanDefinitionCount());
    }
}

(4) 主程序

public class SpringApplicationContext {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        HelloWorld bean = context.getBean(HelloWorld.class);
        System.out.println(bean);
    }
}

(5) 结果
分析：BeanDefinitionRegistryPostProcessor加强BeanFactoryPostProcessor，并且先运行postProcessBeanDefinitionRegistry，在运行postProcessBeanFactory。
在这里插入图片描述

4 源码调试

在这里插入图片描述
(1) 分析方法栈

(2) IOC初始化调用位置 AbstractApplicationContext.，refresh方法
(3) PostProcessorRegistrationDelegate invokeBeanFactoryPostProcessors 源码分析

public static void invokeBeanFactoryPostProcessors(
      ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
 
   Set<String> processedBeans = new HashSet<>();
   if (beanFactory instanceof BeanDefinitionRegistry) {
      BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
      //1 存储BeanFactoryPostProcessor，BeanDefinitionRegistryPostProcessor的处理器
      List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<>();
      List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<>();
      //2 遍历beanFactoryPostProcessors把BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor分开
      for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
         if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
            BeanDefinitionRegistryPostProcessor registryProcessor =
                  (BeanDefinitionRegistryPostProcessor) postProcessor;
            //2.1 执行postProcessBeanDefinitionRegistry，并且添加BeanDefinitionRegistryPostProcessor
            registryProcessor.postProcessBeanDefinitionRegistry(registry);
            registryProcessors.add(registryProcessor);
         }
         else {
            //2.2 添加BeanFactoryPostProcessor
            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.
      //3 当前的currentRegistryProcessors  
      List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
      // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
      //4 获取BeanDefinitionRegistryPostProcessor.class   
      String[] postProcessorNames =
            beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
      //5 找出实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor  
      for (String ppName : postProcessorNames) {
         if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
            currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
            processedBeans.add(ppName);
         }
      }
      //6 排序，添加，并且运行当前所有currentRegistryProcessors的postProcessBeanDefinitionRegistry方法，清空currentRegistryProcessors
      sortPostProcessors(currentRegistryProcessors, beanFactory);
      registryProcessors.addAll(currentRegistryProcessors);
      invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
      currentRegistryProcessors.clear();
      // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
      //7 重新获取，防止上文postProcessBeanDefinitionRegistry的方法添加了新的BeanDefinitionRegistryPostProcessor
      postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
      //8 分类，获取实现Ordered的接口的BeanDefinitionRegistryPostProcessor
      for (String ppName : postProcessorNames) {
         if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
            currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
            processedBeans.add(ppName);
         }
      }
      //9 添加，注册，调取当前BeanDefinitionRegistryPostProcessor所有的postProcessBeanDefinitionRegistry方法，清空currentRegistryProcessors  
      sortPostProcessors(currentRegistryProcessors, beanFactory);
      registryProcessors.addAll(currentRegistryProcessors);
      invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
      currentRegistryProcessors.clear();
      // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
      //10 处理没有实现Ordered， PriorityOrdered接口的BeanDefinitionRegistryPostProcessor   
      boolean reiterate = true;
      while (reiterate) {
         reiterate = false;
         //循环获取，防止BeanDefinitionRegistryPostProcessor添加新的BeanDefinitionRegistryPostProcessor对象    
         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;
            }
         }
         //排序，清空，调用
         sortPostProcessors(currentRegistryProcessors, beanFactory);
         registryProcessors.addAll(currentRegistryProcessors);
         invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
         currentRegistryProcessors.clear();
      }
      // Now, invoke the postProcessBeanFactory callback of all processors handled so far.
      //11 调用所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法和BeanFactoryPostProcessor的postProcessBeanFactory方法
      invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
      invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
   }
   else {
      // Invoke factory processors registered with the context instance.
      invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
   }
   // Do not initialize FactoryBeans here: We need to leave all regular beans
   // uninitialized to let the bean factory post-processors apply to them!
   //12 获取BeanFactoryPostProcessor.class类型beannames 
   String[] postProcessorNames =
         beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
   // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
   // Ordered, and the rest.
   //13 存储PriorityOrdered.class、Ordered、双非的类名
   List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
   List<String> orderedPostProcessorNames = new ArrayList<>();
   List<String> nonOrderedPostProcessorNames = new ArrayList<>();
   //14 分类
   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.
   //15 排序，调用BeanFactoryPostProcessor的postProcessBeanFactory类
   sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
   invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
   // Next, invoke the BeanFactoryPostProcessors that implement Ordered.
   //16 存储，排序，调用BeanFactoryPostProcessor实现了Order的postProcessBeanFactory类
   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.
   //17 最后调用双非的BeanFactoryPostProcessor的postProcessBeanFactory方法
   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();
}

5 ConfigurationClassPostProcessor

作用：注册Bean的信息，但不是实例化Bean
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5.1 引入时机

(1) AnnotationConfigApplicationContext 构造
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(2) AnnotationConfigApplicationContext() 构造

(3)AnnotatedBeanDefinitionReader 构造

(4) AnnotatedBeanDefinitionReader 构造

(5) AnnotationConfigUtils registerAnnotationConfigProcessors

(6) AnnotationConfigUtils registerAnnotationConfigProcessors
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5.2 作用

(1) ConfigurationClassPostProcessor 实现了 PriorityOrdered 所以是最先调用

(2) 调试 PostProcessorRegistrationDelegate invokeBeanFactoryPostProcessors
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(3) PostProcessorRegistrationDelegate invokeBeanDefinitionRegistryPostProcessors

(4) ConfigurationClassPostProcessor postProcessBeanDefinitionRegistry

(5) ConfigurationClassPostProcessor processConfigBeanDefinitions

(6) ConfigurationClassBeanDefinitionReader loadBeanDefinitions
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