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());
}
}
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：
2 BeanDefinitionRegistryPostProcessor
2.1 类图
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。
4 源码调试
(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
5.1 引入时机
(1) AnnotationConfigApplicationContext 构造
(2) AnnotationConfigApplicationContext() 构造
(3)AnnotatedBeanDefinitionReader 构造
(4) AnnotatedBeanDefinitionReader 构造
(5) AnnotationConfigUtils registerAnnotationConfigProcessors
(6) AnnotationConfigUtils registerAnnotationConfigProcessors
5.2 作用
(1) ConfigurationClassPostProcessor 实现了 PriorityOrdered 所以是最先调用
(2) 调试 PostProcessorRegistrationDelegate invokeBeanFactoryPostProcessors
(3) PostProcessorRegistrationDelegate invokeBeanDefinitionRegistryPostProcessors
(4) ConfigurationClassPostProcessor postProcessBeanDefinitionRegistry
(5) ConfigurationClassPostProcessor processConfigBeanDefinitions
(6) ConfigurationClassBeanDefinitionReader loadBeanDefinitions
