springboot中内置tomcat什么时候创建的，又是什么时候启动的？

小咪咪 2023-09-28 12:39 44阅读 0赞

与spring和springboot相关的重要逻辑，如果想了解源头在哪，找refresh准没错

启动类，run

@SpringBootApplication
    public class KafkaBootApplication {
    
    	public static void main(String[] args) {
    		SpringApplication.run(KafkaBootApplication.class, args);
    	}
    
    }

一路run

public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
    		return run(new Class<?>[] { primarySource }, args);
    	}

public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
    		return new SpringApplication(primarySources).run(args);
    	}

直到refreshContext(context)

![005a51c9645946c6b3ce9912eb5ac929.png][]

private void refreshContext(ConfigurableApplicationContext context) {
    		if (this.registerShutdownHook) {
    			shutdownHook.registerApplicationContext(context);
    		}
    		refresh(context);
    	}

protected void refresh(ConfigurableApplicationContext applicationContext) {
    		applicationContext.refresh();
    	}

走到ServletWebServerApplicationContext#refresh()

@Override
    	public final void refresh() throws BeansException, IllegalStateException {
    		try {
    			super.refresh();
    		}
    		catch (RuntimeException ex) {
    			WebServer webServer = this.webServer;
    			if (webServer != null) {
    				webServer.stop();
    			}
    			throw ex;
    		}
    	}

其实调用还是super.refresh()，也就是AbstractApplicationContext的refresh，再调用onRefresh()

![d458a2ebc47a4ccfb1e323573a22016f.png][]

然后又回调回了ServletWebServerApplicationContext\#onRefresh()

这里涉及到一个设计模式，**模板方法设计模式**，父类的onRefresh()是个空方法，留给子类实现。

![7e5417c60be341d5938f73e8509c1e10.png][]

内置的tomcat就是在createWebServer()方法中

![c6622a94f6b64be4b8fcb81c2f257512.png][]

直接显示的new了一个Tomcat()

![b611704671b34c069959800ba0f5cc2d.png][]

创建的只是一个Tomcat对象，需要返回的是 TomcatWebServer，也就是启动了的Tomcat

所以还需要启动Tomcat

![57bbe2b3a7d64258866f39d61758bd94.png][]

把Tomcat当作参数传过来，实例化一个TomcatWebServer对象

![7252f4028c9b4ff6bb8a4b3bcb1c3959.png][]

实例化过程中有个步骤叫初始化initialize()

![9547fe150edc4bf7b5549f32e85a317c.png][]

就是在这个初始化方法中完成了Tomcat的启动

![cbd8459dbad4455ab23f667fb339cc53.png][]

至此，springboot内置的tomcat就创建并启动完成了

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