尚硅谷springboot学习35-启动原理

　　先列出几个重要的事件回调机制

　　配置在META-INF/spring.factories

　　ApplicationContextInitializer

　　SpringApplicationRunListener

　　只需要放在ioc容器中

　　ApplicationRunner

　　CommandLineRunner

 　　启动流程：

　　1、创建SpringApplication对象

initialize(sources); private void initialize(Object[] sources) { //保存主配置类 if (sources != null && sources.length > 0) { this.sources.addAll(Arrays.asList(sources)); } //判断当前是否一个web应用 this.webEnvironment = deduceWebEnvironment(); //从类路径下找到META-INF/spring.factories配置的所有ApplicationContextInitializer；然后保存起来 setInitializers((Collection) getSpringFactoriesInstances( ApplicationContextInitializer.class)); //从类路径下找到ETA-INF/spring.factories配置的所有ApplicationListener setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class)); //从多个配置类中找到有main方法的主配置类 this.mainApplicationClass = deduceMainApplicationClass(); }

　　

　　2、运行run方法

public ConfigurableApplicationContext run(String... args) { StopWatch stopWatch = new StopWatch(); stopWatch.start(); ConfigurableApplicationContext context = null; FailureAnalyzers analyzers = null; configureHeadlessProperty(); //获取SpringApplicationRunListeners；从类路径下META-INF/spring.factories 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); //创建环境完成后回调SpringApplicationRunListener.environmentPrepared()；表示环境准备完成 Banner printedBanner = printBanner(environment); //创建ApplicationContext；决定创建web的ioc还是普通的ioc context = createApplicationContext(); analyzers = new FailureAnalyzers(context); //准备上下文环境;将environment保存到ioc中；而且applyInitializers()； //applyInitializers()：回调之前保存的所有的ApplicationContextInitializer的initialize方法 //回调所有的SpringApplicationRunListener的contextPrepared()； // prepareContext(context, environment, listeners, applicationArguments, printedBanner); //prepareContext运行完成以后回调所有的SpringApplicationRunListener的contextLoaded（）； //s刷新容器；ioc容器初始化（如果是web应用还会创建嵌入式的Tomcat）；Spring注解版 //扫描，创建，加载所有组件的地方；（配置类，组件，自动配置） refreshContext(context); //从ioc容器中获取所有的ApplicationRunner和CommandLineRunner进行回调 //ApplicationRunner先回调，CommandLineRunner再回调 afterRefresh(context, applicationArguments); //所有的SpringApplicationRunListener回调finished方法 listeners.finished(context, null); stopWatch.stop(); if (this.logStartupInfo) { new StartupInfoLogger(this.mainApplicationClass) .logStarted(getApplicationLog(), stopWatch); } //整个SpringBoot应用启动完成以后返回启动的ioc容器； return context; } catch (Throwable ex) { handleRunFailure(context, listeners, analyzers, ex); throw new IllegalStateException(ex); } }

　　3、事件监听机制

　　配置在META-INF/spring.factories

　　ApplicationContextInitializer

public class HelloApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> { @Override public void initialize(ConfigurableApplicationContext applicationContext) { System.out.println("ApplicationContextInitializer...initialize..."+applicationContext); } }

　　SpringApplicationRunListener

public class HelloSpringApplicationRunListener implements SpringApplicationRunListener { //必须有的构造器 public HelloSpringApplicationRunListener(SpringApplication application, String[] args){ } @Override public void starting() { System.out.println("SpringApplicationRunListener...starting..."); } @Override public void environmentPrepared(ConfigurableEnvironment environment) { Object o = environment.getSystemProperties().get("os.name"); System.out.println("SpringApplicationRunListener...environmentPrepared.."+o); } @Override public void contextPrepared(ConfigurableApplicationContext context) { System.out.println("SpringApplicationRunListener...contextPrepared..."); } @Override public void contextLoaded(ConfigurableApplicationContext context) { System.out.println("SpringApplicationRunListener...contextLoaded..."); } @Override public void finished(ConfigurableApplicationContext context, Throwable exception) { System.out.println("SpringApplicationRunListener...finished..."); } }

　　配置（META-INF/spring.factories）　　

org.springframework.context.ApplicationContextInitializer=\ com.atguigu.springboot.listener.HelloApplicationContextInitializer org.springframework.boot.SpringApplicationRunListener=\ com.atguigu.springboot.listener.HelloSpringApplicationRunListener

　　下面两个只需要放在ioc容器中

　　ApplicationRunner

　　

@Component public class HelloApplicationRunner implements ApplicationRunner { @Override public void run(ApplicationArguments args) throws Exception { System.out.println("ApplicationRunner...run...."); } }

　　CommandLineRunner

@Component public class HelloCommandLineRunner implements CommandLineRunner { @Override public void run(String... args) throws Exception { System.out.println("CommandLineRunner...run..."+ Arrays.asList(args)); } }

　　看一下启动的效果

SpringApplicationRunListener...starting... SpringApplicationRunListener...environmentPrepared..Windows 8.1 . ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.5.10.RELEASE) ApplicationContextInitializer...initialize...org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@140e5a13: startup date [Thu Jan 01 08:00:00 CST 1970]; root of context hierarchy SpringApplicationRunListener...contextPrepared... 2019-02-09 02:04:54.489 INFO 8068 --- [ main] c.a.springboot.SpringBoot07Application : Starting SpringBoot07Application on DESKTOP-1IMBL43 with PID 8068 (started by DELL in H:\source-code\src\java-code\javaweb\springboot\基础\spring-boot-07) 2019-02-09 02:04:54.493 INFO 8068 --- [ main] c.a.springboot.SpringBoot07Application : No active profile set, falling back to default profiles: default SpringApplicationRunListener...contextLoaded... 2019-02-09 02:04:54.583 INFO 8068 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@140e5a13: startup date [Sat Feb 09 02:04:54 CST 2019]; root of context hierarchy 2019-02-09 02:04:57.715 INFO 8068 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http) 2019-02-09 02:04:57.729 INFO 8068 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2019-02-09 02:04:57.730 INFO 8068 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.27 2019-02-09 02:04:57.947 INFO 8068 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2019-02-09 02:04:57.947 INFO 8068 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 3365 ms 2019-02-09 02:04:58.247 INFO 8068 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2019-02-09 02:04:58.255 INFO 8068 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2019-02-09 02:04:58.256 INFO 8068 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2019-02-09 02:04:58.257 INFO 8068 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2019-02-09 02:04:58.257 INFO 8068 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2019-02-09 02:04:58.874 INFO 8068 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@140e5a13: startup date [Sat Feb 09 02:04:54 CST 2019]; root of context hierarchy 2019-02-09 02:04:59.148 INFO 8068 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2019-02-09 02:04:59.160 INFO 8068 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) 2019-02-09 02:04:59.291 INFO 8068 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-02-09 02:04:59.292 INFO 8068 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-02-09 02:04:59.428 INFO 8068 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-02-09 02:04:59.955 INFO 8068 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2019-02-09 02:05:00.121 INFO 8068 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http) ApplicationRunner...run.... CommandLineRunner...run...[] SpringApplicationRunListener...finished... 2019-02-09 02:05:00.128 INFO 8068 --- [ main] c.a.springboot.SpringBoot07Application : Started SpringBoot07Application in 6.117 seconds (JVM running for 6.742)

 

转载于:https://www.cnblogs.com/liunianfeiyu/p/10357068.html