概要
详细剖析ServletWebServerFactory实例化过程,整个过程使用多次后置处理对Bean实例化进行干预,完成TomcatServletWebServerFactory进行初始化
ServletWebServerFactory实例化
Spring容器在刷新容器的时候创建WebServer之前,先要创建ServletWebServerFactory
ServletWebServerFactory factory = getWebServerFactory();
从前面的自动配置类代码可以看出,要想得到TomcatServletWebServerFactory,得先实例化FactoryBean:EmbeddedTomcat
public static class EmbeddedTomcat {
@Bean
public TomcatServletWebServerFactory tomcatServletWebServerFactory() {
return new TomcatServletWebServerFactory();
}
}
Spring在实例化TomcatServletWebServerFactory过程中会经过几次后置处理器的干预,它们分别是:
applyBeanPostProcessorsBeforeInitialization
这里面的CommonAnnotationPostProcessor对JSR-250@PostConstruct @PreDestroy处理
postProcessAfterInstantiation
postProcessProperties
postProcessPropertyValues
invokeInitMethods(类似后置处理器)
applyBeanPostProcessorsAfterInitialization
后置处理:applyBeanPostProcessorsBeforeInitialization
org.springframework.context.support.ApplicationContextAwareProcessor#postProcessBeforeInitialization对servletWebServerFactory的处理
ApplicationContextAwareProcessor
因为TomcatServletWebServerFactory没有实现什么XxxAware接口,所以无需处理
WebApplicationContextServletContextAwareProcessor
是对ServletContextAware的处理,因为Spring自带的ApplicationContextAwareProcessor不包含ServletContextAware
ImportAwareBeanPostProcessor
ImportAwareBeanPostProcessor是ConfigurationClassPostProcessor的内部类,因为TomcatServletWebServerFactory没有实现什么ImportAware接口,所以无需处理
BeanPostProcessorChecker
BeanPostProcessorChecker是PostProcessorRegistrationDelegate的内部类,重写的postProcessBeforeInitialization方法本身不包含任何处理
ConfigurationPropertiesBindingPostProcessor
如果Bean被@ConfigurationProperties修饰,则使用该后置处理器将PropertySources与该Bean绑定
MethodValidationPostProcessor
它没有重写postProcessBeforeInitialization方法,而是他的抽象父类AbstractAdvisingBeanPostProcessor重写的,但是犯方法内并没有任何处理
WebServerFactoryCustomizerBeanPostProcessor
它完成了对TomcatServletWebServerFactory Bean(还不是完整的Spring Bean)的一些初始化操作
它的BeanDefinition由ServletWebServerFactoryAutoConfiguration完成注册,并在org.springframework.context.support.AbstractApplicationContext#registerBeanPostProcessors中完成实例化
private void postProcessBeforeInitialization(WebServerFactory webServerFactory) {
/**
* 依次调用从容器中拿出来的WebServerFactoryCustomizer.customize方法
*/
LambdaSafe.callbacks(WebServerFactoryCustomizer.