通过阅读源码看看springboot的启动流程是怎么调用getWebServer这个方法的

àì夳堔傛蜴生んèń 2023-02-26 04:27 5阅读 0赞

1.启动类调用了run方法点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70]  
2.返回一个run继续点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 1]  
3.创建SpringApplication  
返回了两部分 第一部分 new SpringApplication第二部分是调用run 方法先看看第一部分  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 2]  
4.调了个this点进去看看  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 3]  
5.其实SpringBoot启动就着两个步骤，先创建ConfigurableApplicationContext ，然后再调用Run方法。

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) { 
    		this.resourceLoader = resourceLoader;
    		Assert.notNull(primarySources, "PrimarySources must not be null");
    		//保存主类
    		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
    		//判断当前是什么类型项目
    		this.webApplicationType = WebApplicationType.deduceFromClasspath();
    	//从类路径下找到META-INF/spring.factories配置的所有ApplicationContextInitializer
    		setInitializers((Collection) getSpringFactoriesInstances(
    				ApplicationContextInitializer.class));
    	//从类路径下找到META-INF/spring.factories配置的所有ApplicationListener
    		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
    		this.mainApplicationClass = deduceMainApplicationClass();

6.返回去看看run方法  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 4]  
7.运行spring应用程序创建并刷新一个新的

/** * Run the Spring application, creating and refreshing a new * {@link ApplicationContext}. * @param args the application arguments (usually passed from a Java main method) * @return a running {@link ApplicationContext} */
    	public ConfigurableApplicationContext run(String... args) { 
    		StopWatch stopWatch = new StopWatch();
    		stopWatch.start();
    		ConfigurableApplicationContext context = null;
    		Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
    		configureHeadlessProperty();
    		//从类路径下META‐INF/spring.factories，取得SpringApplicationRunListeners;
    		SpringApplicationRunListeners listeners = getRunListeners(args);
    		//回调所有的获取SpringApplicationRunListener.starting()方法
    		listeners.starting();
    			try { 
    		    //封装命令行参数
    			ApplicationArguments applicationArguments = new DefaultApplicationArguments(
    					args);
    		    //准备环境
    			ConfigurableEnvironment environment = prepareEnvironment(listeners,
    					applicationArguments);
    			configureIgnoreBeanInfo(environment);
                //创回调SpringApplicationRunListener.environmentPrepared()；
    //表示环境准备完成
    
    			//打印Banner 
    			Banner printedBanner = printBanner(environment);
                //根据环境创建context
    			context = createApplicationContext();
    		    //错误的异常报表
    			exceptionReporters = getSpringFactoriesInstances(
    					SpringBootExceptionReporter.class,
    					new Class[] {  ConfigurableApplicationContext.class }, context);
    			 //准备上下文环境;
    			//将environment保存到ioc中；
    			//applyInitializers()调用所有的ApplicationContextInitializer的initialize方法
    			//调用所有的SpringApplicationRunListener的contextPrepared()；
    			prepareContext(context, environment, listeners, applicationArguments,
    					printedBanner);
    			//SpringApplicationRunListener的contextLoaded
    			//刷新容器
    			//扫描，创建，加载所有组件；
    			refreshContext(context);
    			afterRefresh(context, applicationArguments);
    			stopWatch.stop();
    			if (this.logStartupInfo) { 
    				new StartupInfoLogger(this.mainApplicationClass)
    						.logStarted(getApplicationLog(), stopWatch);
    			}
    			//所有的SpringApplicationRunListener回调started方法
    			listeners.started(context);
    			//获取所有的ApplicationRunner和CommandLineRunner进行调用
    			callRunners(context, applicationArguments);
    		}
    		catch (Throwable ex) { 
    			handleRunFailure(context, ex, exceptionReporters, listeners);
    			throw new IllegalStateException(ex);
    		}
    		try { 
    			//所有的SpringApplicationRunListener的running()；
    			listeners.running(context);
    		}
    		catch (Throwable ex) { 
    			handleRunFailure(context, ex, exceptionReporters, null);
    			throw new IllegalStateException(ex);
    		}
    		return context;
    	}

8.点进去这个refreshContext方法看看有个refresh(context);刷新上下文继续点进去

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 5]  
9.应用上下文刷新继续点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 6]  
10.可以看到这是spring创建IOC容器的时候执行的代码 找到onRefresh();方法点进去

@Override
    	public void refresh() throws BeansException, IllegalStateException { 
    		synchronized (this.startupShutdownMonitor) { 
    			// Prepare this context for refreshing.
    			prepareRefresh();
    
    			// Tell the subclass to refresh the internal bean factory.
    			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
    
    			// Prepare the bean factory for use in this context.
    			prepareBeanFactory(beanFactory);
    
    			try { 
    				// Allows post-processing of the bean factory in context subclasses.
    				postProcessBeanFactory(beanFactory);
    
    				// Invoke factory processors registered as beans in the context.
    				invokeBeanFactoryPostProcessors(beanFactory);
    
    				// Register bean processors that intercept bean creation.
    				registerBeanPostProcessors(beanFactory);
    
    				// Initialize message source for this context.
    				initMessageSource();
    
    				// Initialize event multicaster for this context.
    				initApplicationEventMulticaster();
    
    				// Initialize other special beans in specific context subclasses.
    				onRefresh();
    
    				// Check for listener beans and register them.
    				registerListeners();
    
    				// Instantiate all remaining (non-lazy-init) singletons.
    				finishBeanFactoryInitialization(beanFactory);
    
    				// Last step: publish corresponding event.
    				finishRefresh();
    			}

11.可以看到这个抽象类里的这个方法 点旁边蓝色小圆圈可以看到继承它的子类  
ServletWebServerApplicationContext点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 7]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 8]  
12.调用了createWebServer();创建web服务器 点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 9]  
13.可以看到在这里调用了getWebServer()这个方法 然后启动tomcat  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 10]  
14.看看实现这个接口的类 点进去Tomcat那个  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 11]  
![在这里插入图片描述][2020071411282017.png]  
15.调用了getWebServer()这个方法  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 12]

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