// full模式
@Configuration(proxyBeanMethods = false)

// 配置類解析順序
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)

// 條件注解：表示項目依賴中要有ServletRequest類（server api）
@ConditionalOnClass(ServletRequest.class)
// 表示項目應用類型得是SpringMVC（在啟動過程中獲取的SpringBoot應用類型）
@ConditionalOnWebApplication(type = Type.SERVLET)

// 讀取server下的配置文件
@EnableConfigurationProperties(ServerProperties.class)

// import具體的加載配置的類和具體web實現(xiàn)容器
@Import({ ServletWebServerFactoryAutoConfiguration.BeanPostProcessorsRegistrar.class,
		ServletWebServerFactoryConfiguration.EmbeddedTomcat.class,
		ServletWebServerFactoryConfiguration.EmbeddedJetty.class,
		ServletWebServerFactoryConfiguration.EmbeddedUndertow.class })
public class ServletWebServerFactoryAutoConfiguration {
	......
}

@Configuration(proxyBeanMethods = false)
// tomcat內(nèi)部的類，肯定都存在
@ConditionalOnClass({ Servlet.class, Tomcat.class, UpgradeProtocol.class })

// 程序員如果自定義了ServletWebServerFactory的Bean，那么這個Bean就不加載。
@ConditionalOnMissingBean(value = ServletWebServerFactory.class, search = SearchStrategy.CURRENT)
static class EmbeddedTomcat {
    @Bean
    TomcatServletWebServerFactory tomcatServletWebServerFactory(
        ObjectProvider<TomcatConnectorCustomizer> connectorCustomizers,
        ObjectProvider<TomcatContextCustomizer> contextCustomizers,
        ObjectProvider<TomcatProtocolHandlerCustomizer<?>> protocolHandlerCustomizers) {
            TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();
            // orderedStream()調(diào)用時會去Spring容器中找到TomcatConnectorCustomizer類型的Bean，默認是沒有的，程序員可以自己定義。這個Bean可以設置一些tomcat的配置，比如端口、協(xié)議...
            // TomcatConnectorCustomizer：是用來配置Tomcat中的Connector組件的
            factory.getTomcatConnectorCustomizers().addAll(connectorCustomizers.orderedStream().collect(Collectors.toList()));
            // TomcatContextCustomizer：是用來配置Tomcat中的Context組件的
            factory.getTomcatContextCustomizers().addAll(contextCustomizers.orderedStream().collect(Collectors.toList()));
            // TomcatProtocolHandlerCustomizer：是用來配置Tomcat中的ProtocolHandler組件的
            factory.getTomcatProtocolHandlerCustomizers().addAll(protocolHandlerCustomizers.orderedStream().collect(Collectors.toList()));
            return factory;
        }
    }
}

public WebServer getWebServer(ServletContextInitializer... initializers) {
    if (this.disableMBeanRegistry) {
        Registry.disableRegistry();
    }
    // 構建tomcat對象
    Tomcat tomcat = new Tomcat();

    // 設置相關的屬性
    File baseDir = (this.baseDirectory != null) ? this.baseDirectory : createTempDir("tomcat");
    tomcat.setBaseDir(baseDir.getAbsolutePath());
    for (LifecycleListener listener : this.serverLifecycleListeners) {
        tomcat.getServer().addLifecycleListener(listener);
    }
    Connector connector = new Connector(this.protocol);
    connector.setThrowOnFailure(true);
    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);

    // 啟動tomcat，這個方法內(nèi)部有this.tomcat.start();
    return getTomcatWebServer(tomcat);
}

protected void onRefresh() {
    // 模板方法，先調(diào)用它父類的，一般是空方法
    super.onRefresh();
    try {
        // 創(chuàng)建web容器
        createWebServer();
    }
    catch (Throwable ex) {
        throw new ApplicationContextException("Unable to start web server", ex);
    }
}

// 最核心的倆行代碼
private void createWebServer() {
    ......
    // 獲取web容器，多個或者沒有的時候報錯
    ServletWebServerFactory factory = getWebServerFactory();

    // 調(diào)用這個容器的getWebServer方法，上面的啟動tomcat的方法！
    this.webServer = factory.getWebServer(getSelfInitializer());
    ......
}

protected ServletWebServerFactory getWebServerFactory() {
    // Use bean names so that we don't consider the hierarchy

    // 得到所有類型為ServletWebServerFactory的Bean。TomcatServletWebServerFactory、JettyServletWebServerFactory、UndertowServletWebServerFactory都是他得到子類！
    String[] beanNames = getBeanFactory().getBeanNamesForType(ServletWebServerFactory.class);

    // 不存在，報錯
    if (beanNames.length == 0) {
        throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.");
    }

    // 存在不止一個，報錯！
    if (beanNames.length > 1) {
        throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to multiple ServletWebServerFactory beans : " + StringUtils.arrayToCommaDelimitedString(beanNames));
    }

    // 返回唯一的一個web容器！
    return getBeanFactory().getBean(beanNames[0], ServletWebServerFactory.class);
}

public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
    // Bean工廠，一個Aware回調(diào)進行賦值
    if (this.beanFactory == null) {
        return;
    }
    // 注冊webServerFactoryCustomizerBeanPostProcessor這個Bean。
    registerSyntheticBeanIfMissing(registry, "webServerFactoryCustomizerBeanPostProcessor",
        WebServerFactoryCustomizerBeanPostProcessor.class,
        WebServerFactoryCustomizerBeanPostProcessor::new);

    // 注冊errorPageRegistrarBeanPostProcessor
    registerSyntheticBeanIfMissing(registry, "errorPageRegistrarBeanPostProcessor",
        ErrorPageRegistrarBeanPostProcessor.class, ErrorPageRegistrarBeanPostProcessor::new);
}

private void postProcessBeforeInitialization(WebServerFactory webServerFactory) {
    // 找到WebServerFactoryCustomizer的Bean
    LambdaSafe.callbacks(WebServerFactoryCustomizer.class, getCustomizers(), webServerFactory)
        // 標記日志用的類
        .withLogger(WebServerFactoryCustomizerBeanPostProcessor.class)
        // 調(diào)用customize方法，傳入webServerFactory
        .invoke((customizer) -> customizer.customize(webServerFactory));
}

@Override
public void customize(ConfigurableServletWebServerFactory factory) {
    PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
    map.from(this.serverProperties::getPort).to(factory::setPort);
    map.from(this.serverProperties::getAddress).to(factory::setAddress);
    map.from(this.serverProperties.getServlet()::getContextPath).to(factory::setContextPath);
    map.from(this.serverProperties.getServlet()::getApplicationDisplayName).to(factory::setDisplayName);
    map.from(this.serverProperties.getServlet()::isRegisterDefaultServlet).to(factory::setRegisterDefaultServlet);
    map.from(this.serverProperties.getServlet()::getSession).to(factory::setSession);
    map.from(this.serverProperties::getSsl).to(factory::setSsl);
    map.from(this.serverProperties.getServlet()::getJsp).to(factory::setJsp);
    map.from(this.serverProperties::getCompression).to(factory::setCompression);
    map.from(this.serverProperties::getHttp2).to(factory::setHttp2);
    map.from(this.serverProperties::getServerHeader).to(factory::setServerHeader);
    map.from(this.serverProperties.getServlet()::getContextParameters).to(factory::setInitParameters);
    map.from(this.serverProperties.getShutdown()).to(factory::setShutdown);
    for (WebListenerRegistrar registrar : this.webListenerRegistrars) {
        registrar.register(factory);
    }
    if (!CollectionUtils.isEmpty(this.cookieSameSiteSuppliers)) {
        factory.setCookieSameSiteSuppliers(this.cookieSameSiteSuppliers);
    }
}

@Bean
public ServletWebServerFactoryCustomizer servletWebServerFactoryCustomizer(ServerProperties serverProperties, ObjectProvider<WebListenerRegistrar> webListenerRegistrars, ObjectProvider<CookieSameSiteSupplier> cookieSameSiteSuppliers) {
    return new ServletWebServerFactoryCustomizer(serverProperties,webListenerRegistrars.orderedStream().collect(Collectors.toList()),cookieSameSiteSuppliers.orderedStream().collect(Collectors.toList()));
}