SpringBoot内嵌服务器启动流程

最新推荐文章于 2025-03-19 21:02:06 发布

InAHurryv

最新推荐文章于 2025-03-19 21:02:06 发布

阅读量367

点赞数

CC 4.0 BY-SA版权

分类专栏： spring

本文链接：https://blog.youkuaiyun.com/mmmmhello/article/details/113963182

spring 专栏收录该内容

13 篇文章

订阅专栏

这篇博客详细介绍了Spring Boot如何在应用启动时自动配置并使用内嵌的Tomcat服务器。在`ServletWebServerFactoryAutoConfiguration`类中，通过`EmbeddedTomcat.class`引入Tomcat工厂，创建并启动Web服务器。在`createWebServer`方法中，实例化`Tomcat`，设置相关配置，并最终启动。这个过程展示了Spring Boot如何无缝集成Tomcat，使得开发者无需手动管理Web容器。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

我们知道spring 底层是servlet,而servlet必须运行在web容器中,而我们使用spring 并没有使用自己定义的tomcat,那为什么会有Tomcat给我们用呢？

org.springframework.boot:spring-boot-starter-tomcat:2.4.3

ServletWebServerFactoryAutoConfiguration.java 中会首先导入
ServletWebServerFactoryConfiguration.EmbeddedTomcat.class （假设存在的话）

@Import({ ServletWebServerFactoryAutoConfiguration.BeanPostProcessorsRegistrar.class,
		ServletWebServerFactoryConfiguration.EmbeddedTomcat.class,
		ServletWebServerFactoryConfiguration.EmbeddedJetty.class,
		ServletWebServerFactoryConfiguration.EmbeddedUndertow.class })
public class ServletWebServerFactoryAutoConfiguration {

而ServletWebServerFactoryConfiguration.EmbeddedTomcat.class 会给容器中加入TomcatServletWebServerFactory 的bean,ServletWebServerApplicationContext在初始化好之后会创建webserver,并启动。

	protected void onRefresh() {
		super.onRefresh();
		try {
			createWebServer();
		}
		catch (Throwable ex) {
			throw new ApplicationContextException("Unable to start web server", ex);
		}
	}

	private void createWebServer() {
		WebServer webServer = this.webServer;
		ServletContext servletContext = getServletContext();
		if (webServer == null && servletContext == null) {
			StartupStep createWebServer = this.getApplicationStartup().start("spring.boot.webserver.create");
			ServletWebServerFactory factory = getWebServerFactory();
			createWebServer.tag("factory", factory.getClass().toString());
			this.webServer = factory.getWebServer(getSelfInitializer());
			createWebServer.end();
			getBeanFactory().registerSingleton("webServerGracefulShutdown",
					new WebServerGracefulShutdownLifecycle(this.webServer));
			getBeanFactory().registerSingleton("webServerStartStop",
					new WebServerStartStopLifecycle(this, this.webServer));
		}
		else if (servletContext != null) {
			try {
				getSelfInitializer().onStartup(servletContext);
			}
			catch (ServletException ex) {
				throw new ApplicationContextException("Cannot initialize servlet context", ex);
			}
		}
		initPropertySources();
	}

public WebServer getWebServer(ServletContextInitializer... initializers) {
		if (this.disableMBeanRegistry) {
			Registry.disableRegistry();
		}
		Tomcat tomcat = new Tomcat();
		File baseDir = (this.baseDirectory != null) ? this.baseDirectory : createTempDir("tomcat");
		tomcat.setBaseDir(baseDir.getAbsolutePath());
		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);
		return getTomcatWebServer(tomcat);
	}

	protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
		return new TomcatWebServer(tomcat, getPort() >= 0, getShutdown());
	}

public TomcatWebServer(Tomcat tomcat, boolean autoStart, Shutdown shutdown) {
		Assert.notNull(tomcat, "Tomcat Server must not be null");
		this.tomcat = tomcat;
		this.autoStart = autoStart;
		this.gracefulShutdown = (shutdown == Shutdown.GRACEFUL) ? new GracefulShutdown(tomcat) : null;
		initialize();
	}

	private void initialize() throws WebServerException {
		logger.info("Tomcat initialized with port(s): " + getPortsDescription(false));
		synchronized (this.monitor) {
			try {
				addInstanceIdToEngineName();

				Context context = findContext();
				context.addLifecycleListener((event) -> {
					if (context.equals(event.getSource()) && Lifecycle.START_EVENT.equals(event.getType())) {
						// Remove service connectors so that protocol binding doesn't
						// happen when the service is started.
						removeServiceConnectors();
					}
				});

				// Start the server to trigger initialization listeners
				this.tomcat.start();

				// We can re-throw failure exception directly in the main thread
				rethrowDeferredStartupExceptions();

				try {
					ContextBindings.bindClassLoader(context, context.getNamingToken(), getClass().getClassLoader());
				}
				catch (NamingException ex) {
					// Naming is not enabled. Continue
				}

				// Unlike Jetty, all Tomcat threads are daemon threads. We create a
				// blocking non-daemon to stop immediate shutdown
				startDaemonAwaitThread();
			}
			catch (Exception ex) {
				stopSilently();
				destroySilently();
				throw new WebServerException("Unable to start embedded Tomcat", ex);
			}
		}
	}