The extension interface is involved in the SpringBoot startup process


SpringApplicationRunListener Interface
1,ApplicationListener Interface is ApplicationContext Event listener for

2,EnvironmentPostProcessor Interface  
Context context postprocessor, call in event
3,PropertySourceLoader Interface Customize the profile loader and resolve the profile properties by yourself 4,ApplicationContextInitializer Interface context initializer
5,BeanFactoryPostProcessor Interface pair BeanFactory The post processor is operated 6,Aware Interface and its sub interfaces Will be refreshContext()Method bean Call, instance Aware Interface method of sub interface. Used to get Spring The objects related to startup are directly called when needed after the project is started 7,BeanPostProcessor Interface be used for bean Initialization method init
-method Processing before and after calling.

8,ApplicationRunner and CommandLineRunner Interface


ApplicationListener, ApplicationContextInitializer, beanfactoryprocessor and BeanPostProcessor interfaces belong to the original Spring framework
EnvironmentPostProcessor, PropertySourceLoader, ApplicationRunner and SpringApplicationRunListener interfaces are new extension interfaces of SpringBoot


SpringApplicationRunListener interface

Event broadcasting in SpringBoot is to distribute events through the listener SpringApplicationRunListener interface implementation class EventPublishingRunListener, so as to call the ApplicationListener listener

So we can configure a custom springboot listener

It is configured in meta-inf / spring Configuration in the factories file

# Run Listeners



1. ApplicationListener interface

yes Spring The event listener in each stage of the application life cycle can trigger the operation we want to perform at any stage
 Be responsible for corresponding treatment at each stage
 such as
ApplicationEnvironmentPreparedEvent Load the profile properties into the data source in the environment preparation completion event
The custom listener configuration is also configured in meta-inf / spring Factories in files
# Application Listeners



2. EnvironmentPostProcessor interface

Context post processor. ApplicationEnvironmentPreparedEvent Call in event
 initialization systemProperties,systemEnvironment Processing after attribute source( servletConfigInitParams,servletContextInitParams Both attribute sources (uninitialized)
such as
Properties for loading profiles{.xml ,.properties,.yml,.yaml Suffix file}To system property source
 Add the configuration file to the attribute source after reading
propertySources.add(new OriginTrackedMapPropertySource(name + documentNumber,

This custom configuration is also configured in meta-inf / spring In the factories file

# Environment Post Processors



3. PropertySourceLoader interface

Customize the profile loader and resolve the profile properties by yourself,
For example, parsing.json The suffix's profile attribute is added to the system
 Reference link:

It is configured in meta-inf / spring Configuration mode in the factories file

# PropertySource Loaders



4. ApplicationContextInitializer interface

stay springBoot At startup prepareContext() These interface pairs are called when the context is prepared applicationContext Do some initialization.
Call time
ApplicationEnvironmentPreparedEvent After the event context is ready ApplicationPreparedEvent Call before event such as ContextIdApplicationContextInitializer Initializer for context generation contextId context id ConfigurationWarningsApplicationContextInitializer increase BeanFactory Factory post processor context.addBeanFactoryPostProcessor,Warning information used to report configuration errors during startup postProcessBeanDefinitionRegistry()Processing in method

It is configured in meta-inf / spring Configuration mode in factories file

# Application Context Initializers



5. Beanfactoryprocessor interface

Sub interface: BeanDefinitionRegistryPostProcessor, which can also implement sub interfaces to operate beanfactory. Post processor that operates on beanfactory

In general: you can register custom beans through the BeanDefinitionRegistryPostProcessor interface method (you can also operate beanFactory to do the corresponding operation)

Trigger time: refreshContext(context) = = "5.4 invokebeanfactoryprocessors (beanfactory)

Can be initialized bean We will customize it before BeanFactoryPostProcessor Implementation class registered to BeanFactory In,
BeanDefinitionRegistryPostProcessor Interface implementation class, which can be customized in the bean We will customize it before defining it Bean Define register to BeanFactory in

Spring Customize for us Bean The analysis of is also through BeanDefinitionRegistryPostProcessor Interface
 Implementation class ConfigurationClassPostProcessor To scan and register bean definition
 The execution process is:
    First ApplicationContext of beanFactoryPostProcessors Convert list to
    BeanDefinitionRegistryPostProcessor(registryProcessors (registered processor)
    and BeanFactoryPostProcessor(regularPostProcessors Rule processor)
    First, it will be executed registryProcessors Registered processor postProcessBeanDefinitionRegistry(registry)Method bean Defined registration
    Registration for the first time
    Will get BeanFactory Built in BeanDefinitionRegistryPostProcessor Interface implementation class, and this class should implement PriorityOrdered Interface==>ConfigurationClassPostProcessor
    Will call ConfigurationClassPostProcessor Class to scan and register all bean definition.
    Second registration:
        Will get BeanFactory Acquired after scanning in BeanDefinitionRegistryPostProcessor Interface implementation class, and this class should implement Ordered Interface
        Call registration method
    Third registration:
        Same acquisition BeanDefinitionRegistryPostProcessor Interface implementation, except for the above implementation classes
        such as mybatis dependent bean Registration is the third registration( MapperScannerConfigurer)
After the registration operation, the above BeanDefinitionRegistryPostProcessor and BeanFactoryPostProcessor Interface implementation class
Call interface method postProcessor.postProcessBeanFactory(beanFactory),beanFactory Post operation of

BeanFactoryPostProcessor or BeanDefinitionRegistryPostProcessor custom implementation classes can be registered before this is called

That is, refreshContext(context); Before refreshing the context

ApplicationContext can be called when the ApplicationPreparedEvent event event is triggered Addbeanfactoryprocessor() method added to

Beanfactoryprocessors list

Of course, you can also add before this event.  



6. Aware interface and its sub interfaces

There are many interfaces to implement Aware interface

Trigger timing: refreshContext(context) = = 6.0, finishBeanFactoryInitialization(beanFactory)

Distinguish according to different calling places:



The above three interfaces are in

AbstractAutowireCapableBeanFactory of initializeBean(beanName, exposedObject, mbd);method invokeAwareMethods(beanName, bean);Method will handle


ApplicationContextAwareProcessor Processing implementation in post processor
ApplicationEventPublisherAware,MessageSourceAware,ApplicationContextAware Of these interfaces Bean Interface method call

6.3 webapplicationcontextservletcontextawareprocessor post processor processing

bean that implements ServletContextAware interface


7. BeanPostProcessor interface

It is equivalent to interceptors before and after bean initialization method calls

It will be processed before and after the initialization method init method call of the Bean

BeanPostProcessor.postProcessBeforeInitialization(Object bean, String beanName) Call before initialization
BeanPostProcessor.postProcessAfterInitialization(Object bean, String beanName)    Call after initialization


8. ApplicationRunner and CommandLineRunner interfaces

It is called before the ApplicationReadyEvent event is triggered after the ApplicationStartedEvent event.

Used to perform post startup operations.

For example, my customized @ EventBusListener annotation is added to beans. After all beans are initialized, I need to obtain this bean list and register it in my event center for asynchronous event subscription, publishing and execution of stand-alone applications

public class MyApplicationRunner implements ApplicationRunner {
    public void run(ApplicationArguments args) throws Exception {
        EventBusCenter eventBusCenter = SpringContextUtils.getBean(EventBusCenter.class);
        // Get all with @EventBusListener of bean,Register them as listeners
        Map<String, Object> beansWithAnnotation = SpringContextUtils.getApplicationContext().getBeansWithAnnotation(EventBusListener.class);
        List<Object> listeners = beansWithAnnotation.entrySet().stream().map(Map.Entry::getValue).collect(Collectors.toList());

Of course, we can also use the event listener to perform this operation. Be flexible


To be added


Posted by BAM1979 on Wed, 13 Apr 2022 19:59:08 +0930