EmbeddedServletContainerAutoConfiguration:嵌入式的 Servlet 容器自動配置
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//導入BeanPostProcessorsRegistrar:給容器中導入一些組件
//導入了EmbeddedServletContainerCustomizerBeanPostProcessor:
//後置處理器:bean初始化前後(剛創建完對象,還沒賦值賦值)執行初始化工作
public class EmbeddedServletContainerAutoConfiguration {}
@Configuration
@ConditionalOnClass({ Servlet.class, Tomcat.class })//判斷當前是否引入了Tomcat依賴
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)//判斷當前容器是否缺失了用戶自定義的EmbeddedServletContainerFactory:嵌入式的Servlet容器工廠。作用:創建嵌入式的Servlet容器
public static class EmbeddedTomcat {
@Bean
public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
return new TomcatEmbeddedServletContainerFactory();
}
}
/**
* Nested configuration if Jetty is being used.
*/
@Configuration
@ConditionalOnClass({ Servlet.class, Server.class, Loader.class,
WebAppContext.class })
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
public static class EmbeddedJetty {
@Bean
public JettyEmbeddedServletContainerFactory jettyEmbeddedServletContainerFactory() {
return new JettyEmbeddedServletContainerFactory();
}
}
/**
* Nested configuration if Undertow is being used.
*/
@Configuration
@ConditionalOnClass({ Servlet.class, Undertow.class, SslClientAuthMode.class })
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
public static class EmbeddedUndertow {
@Bean
public UndertowEmbeddedServletContainerFactory undertowEmbeddedServletContainerFactory() {
return new UndertowEmbeddedServletContainerFactory();
}
}
1、EmbeddedServletContainerFactory:嵌入式 Servlet 容器工廠
public interface EmbeddedServletContainerFactory {
//獲取嵌入式的Servlet容器
EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers);
}
2、EmbeddedServletContainer:嵌入式的 Servlet 容器
3、以 TomcatEmbeddedServletContainerFactory 爲例
@Override
public EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers) {
//創建一個Tomcat
Tomcat tomcat = new Tomcat();
//配置Tomcat的基本環節
File baseDir = (this.baseDirectory != null ? this.baseDirectory
: createTempDir("tomcat"));
tomcat.setBaseDir(baseDir.getAbsolutePath());
Connector connector = new Connector(this.protocol);
tomcat.getService().addConnector(connector);
customizeConnector(connector);
tomcat.setConnector(connector);
tomcat.getHost().setAutoDeploy(false);
configureEngine(tomcat.getEngine());
for (Connector additionalConnector : this.additionalTomcatConnectors) {
tomcat.getService().addConnector(additionalConnector);
}
prepareContext(tomcat.getHost(), initializers);
//將配置好的Tomcat傳入進去,返回一個EmbeddedServletContainer;並且啓動Tomcat服務器
return getTomcatEmbeddedServletContainer(tomcat);
}
4、對嵌入式容器的配置修改是怎麼生效的?
(1) 配置ServerProperties
(2) 配置EmbeddedServletContainerCustomizer
EmbeddedServletContainerCustomizer:定製器幫我們修改了 Servlet 容器的配置。修改的原理是什麼?
5、容器中導入了 EmbeddedServletContainerCustomizerBeanPostProcessor
//初始化之前
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
//如果當前初始化的是一個ConfigurableEmbeddedServletContainer類型的組件
if (bean instanceof ConfigurableEmbeddedServletContainer) {
//
postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
}
return bean;
}
//ServerProperties也是定製器
private void postProcessBeforeInitialization(
ConfigurableEmbeddedServletContainer bean) {
//獲取所有的定製器,調用每一個定製器的customize方法來給Servlet容器進行屬性賦值(比如端口號、訪問路徑)
for (EmbeddedServletContainerCustomizer customizer : getCustomizers()) {
customizer.customize(bean);
}
}
private Collection<EmbeddedServletContainerCustomizer> getCustomizers() {
if (this.customizers == null) {
// Look up does not include the parent context
this.customizers = new ArrayList<EmbeddedServletContainerCustomizer>(
this.beanFactory
//從容器中獲取所有這個類型的組件:EmbeddedServletContainerCustomizer
//結論:定製Servlet容器,給容器中添加一個EmbeddedServletContainerCustomizer類型的組件
.getBeansOfType(EmbeddedServletContainerCustomizer.class,
false, false)
.values());
Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
this.customizers = Collections.unmodifiableList(this.customizers);
}
return this.customizers;
}
流程:
1)Spring Boot 根據導入的依賴,給容器中添加相應的EmbeddedServletContainerFactory【如:TomcatEmbeddedServletContainerFactory】
2)容器中某個組件要創建對象就會驚動後置處理器:EmbeddedServletContainerCustomizerBeanPostProcessor
只要是嵌入式的 Servlet 容器工廠,後置處理器就工作。
3)後置處理器,從容器中獲取所有的 EmbeddedServletContainerCustomizer,調用定製器的定製方法。