Look at the following piece of code, why a @SpringBootApplication annotations can be automatically executed more than N work?
@EnableAsync
@SpringBootApplication
public class NimitzApplication {
public static void main(String[] args) {
new SpringApplicationBuilder(NimitzApplication.class).web(true).run(args);
}
}
process
-
1 SpringApplication.run(Object source, String... args)
-
2 core processes in ConfigurableApplicationContext run (String ... args)
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
analyzers = new FailureAnalyzers(context);
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
refreshContext(context);
afterRefresh(context, applicationArguments);
listeners.finished(context, null);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
- 3 magic process
SpringApplication.refreshContext
-> AbstractApplicationContext.invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory)
-> PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors
-> ConfigurationClassPostProcessor.processConfigBeanDefinitions
-> ConfigurationClassParser.parse
-> ConfigurationClassParser.processConfigurationClass
// 最终 sourceClass是所有魔法的入口了
-> ConfigurationClassParser.doProcessConfigurationClass(configClass, sourceClass);
5 @import是最核心的注解,各种功能实际上是由三种类型的实现的
@Configuration classes, ImportSelector and ImportBeanDefinitionRegistrar implementations