如何在SpringBoot中启动Tomcat?针对这个问题,这篇文章详细介绍了相对应的分析和解答,希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。springboot是什么springboot一种全新的编程规范,其设计目的是用来
如何在SpringBoot中启动Tomcat?针对这个问题,这篇文章详细介绍了相对应的分析和解答,希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。
springboot一种全新的编程规范,其设计目的是用来简化新Spring应用的初始搭建以及开发过程,SpringBoot也是一个服务于框架的框架,服务范围是简化配置文件。
开发阶段对我们来说使用内置的tomcat是非常够用了,当然也可以使用jetty。
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-WEB</artifactId> <version>2.1.6.RELEASE</version></dependency>
@SpringBootApplicationpublic class MySpringbootTomcatStarter{ public static void main(String[] args) { Long time=System.currentTimeMillis(); SpringApplication.run(MySpringbootTomcatStarter.class); System.out.println("===应用启动耗时:"+(System.currentTimeMillis()-time)+"==="); }}
这里是main函数入口,两句代码最耀眼,分别是SpringBootApplication注解和SpringApplication.run()方法。
发布的时候,目前大多数的做法还是排除内置的tomcat,打瓦包(war)然后部署在生产的tomcat中,好吧,那打包的时候应该怎么处理?
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <!-- 移除嵌入式tomcat插件 --> <exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> </exclusion> </exclusions></dependency><!--添加servlet-api依赖---><dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope></dependency>
更新main函数,主要是继承SpringBootServletInitializer,并重写configure()方法。
@SpringBootApplicationpublic class MySpringbootTomcatStarter extends SpringBootServletInitializer { public static void main(String[] args) { Long time=System.currentTimeMillis(); SpringApplication.run(MySpringbootTomcatStarter.class); System.out.println("===应用启动耗时:"+(System.currentTimeMillis()-time)+"==="); } @Override protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) { return builder.sources(this.getClass()); }}
public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) { return run(new Class[]{primarySource}, args);}
--这里run方法返回的是ConfigurableApplicationContext
public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) { return (new SpringApplication(primarySources)).run(args);}
public ConfigurableApplicationContext run(String... args) { ConfigurableApplicationContext context = null; Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList(); this.configureHeadlessProperty(); SpringApplicationRunListeners listeners = this.getRunListeners(args); listeners.starting(); Collection exceptionReporters; try { ApplicationArguments applicationArguments = new DefaultApplicationArguments(args); ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments); this.configureIgnoreBeanInfo(environment); //打印banner,这里你可以自己涂鸦一下,换成自己项目的loGo Banner printedBanner = this.printBanner(environment); //创建应用上下文 context = this.createApplicationContext(); exceptionReporters = this.getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[]{ConfigurableApplicationContext.class}, context); //预处理上下文 this.prepareContext(context, environment, listeners, applicationArguments, printedBanner); //刷新上下文 this.refreshContext(context); //再刷新上下文 this.afterRefresh(context, applicationArguments); listeners.started(context); this.callRunners(context, applicationArguments); } catch (Throwable var10) { } try { listeners.running(context); return context; } catch (Throwable var9) { }}
既然我们想知道tomcat在SpringBoot中是怎么启动的,那么run方法中,重点关注创建应用上下文(createApplicationContext)和刷新上下文(refreshContext)。
//创建上下文protected ConfigurableApplicationContext createApplicationContext() { Class<?> contextClass = this.applicationContextClass; if (contextClass == null) { try { switch(this.webApplicationType) { case SERVLET: //创建AnnotationConfigServletWebServerApplicationContext contextClass = Class.forName("org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext"); break; case ReactIVE: contextClass = Class.forName("org.springframework.boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext"); break; default: contextClass = Class.forName("org.springframework.context.annotation.AnnotationConfigApplicationContext"); } } catch (ClassNotFoundException var3) { throw new IllegalStateException("Unable create a default ApplicationContext, please specify an ApplicationContextClass", var3); } } return (ConfigurableApplicationContext)BeanUtils.instantiateClass(contextClass);}
这里会创建AnnotationConfigServletWebServerApplicationContext类。
而AnnotationConfigServletWebServerApplicationContext类继承了ServletWebServerApplicationContext,而这个类是最终集成了AbstractApplicationContext。
//SpringApplication.java//刷新上下文private void refreshContext(ConfigurableApplicationContext context) { this.refresh(context); if (this.reGISterShutdownHook) { try { context.registerShutdownHook(); } catch (AccessControlException var3) { } }}
//这里直接调用最终父类AbstractApplicationContext.refresh()方法protected void refresh(ApplicationContext applicationContext) { ((AbstractApplicationContext)applicationContext).refresh();}//AbstractApplicationContext.javapublic void refresh() throws BeansException, IllegalStateException { synchronized(this.startupShutdownMonitor) { this.prepareRefresh(); ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory(); this.prepareBeanFactory(beanFactory); try { this.postProcessBeanFactory(beanFactory); this.invokeBeanFactoryPostProcessors(beanFactory); this.registerBeanPostProcessors(beanFactory); this.initMessageSource(); this.initApplicationEventMulticaster(); //调用各个子类的onRefresh()方法,也就说这里要回到子类:ServletWebServerApplicationContext,调用该类的onRefresh()方法 this.onRefresh(); this.registerListeners(); this.finishBeanFactoryInitialization(beanFactory); this.finishRefresh(); } catch (BeansException var9) { this.destroyBeans(); this.cancelRefresh(var9); throw var9; } finally { this.resetCommonCaches(); } }}
//ServletWebServerApplicationContext.java//在这个方法里看到了熟悉的面孔,this.createWebServer,神秘的面纱就要揭开了。protected void onRefresh() { super.onRefresh(); try { this.createWebServer(); } catch (Throwable var2) { }}//ServletWebServerApplicationContext.java//这里是创建webServer,但是还没有启动tomcat,这里是通过ServletWebServerFactory创建,那么接着看下ServletWebServerFactoryprivate void createWebServer() { WebServer webServer = this.webServer; ServletContext servletContext = this.getServletContext(); if (webServer == null && servletContext == null) { ServletWebServerFactory factory = this.getWebServerFactory(); this.webServer = factory.getWebServer(new ServletContextInitializer[]{this.getSelfInitializer()}); } else if (servletContext != null) { try { this.getSelfInitializer().onStartup(servletContext); } catch (ServletException var4) { } } this.initPropertySources();}//接口public interface ServletWebServerFactory { WebServer getWebServer(ServletContextInitializer... initializers);}//实现AbstractServletWebServerFactoryJettyServletWebServerFactoryTomcatServletWebServerFactoryUndertowServletWebServerFactory
这里ServletWebServerFactory接口有4个实现类
而其中我们常用的有两个:TomcatServletWebServerFactory和JettyServletWebServerFactory。
//TomcatServletWebServerFactory.java//这里我们使用的tomcat,所以我们查看TomcatServletWebServerFactory。到这里总算是看到了tomcat的踪迹。@Overridepublic WebServer getWebServer(ServletContextInitializer... initializers) { Tomcat tomcat = new Tomcat(); File baseDir = (this.baseDirectory != null) ? this.baseDirectory : createTempDir("tomcat"); tomcat.setBaseDir(baseDir.getAbsolutePath()); //创建Connector对象 Connector connector = new Connector(this.protocol); 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);} //Tomcat.java//返回Engine容器,看到这里,如果熟悉tomcat源码的话,对engine不会感到陌生。public Engine getEngine() { Service service = getServer().findServices()[0]; if (service.getContainer() != null) { return service.getContainer(); } Engine engine = new StandardEngine(); engine.setName( "Tomcat" ); engine.setDefaultHost(hostname); engine.setRealm(createDefaultRealm()); service.setContainer(engine); return engine;}//Engine是最高级别容器,Host是Engine的子容器,Context是Host的子容器,Wrapper是Context的子容器
getWebServer这个方法创建了Tomcat对象,并且做了两件重要的事情:把Connector对象添加到tomcat中,configureEngine(tomcat.getEngine());
getWebServer方法返回的是TomcatWebServer。
//TomcatWebServer.java//这里调用构造函数实例化TomcatWebServerpublic TomcatWebServer(Tomcat tomcat, boolean autoStart) { Assert.notNull(tomcat, "Tomcat Server must not be null"); this.tomcat = tomcat; this.autoStart = autoStart; initialize();}private void initialize() throws WebServerException { //在控制台会看到这句日志 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())) { removeServiceConnectors(); } }); //===启动tomcat服务=== this.tomcat.start(); rethrowDeferredStartupExceptions(); try { ContextBindings.bindClassLoader(context, context.getNamingToken(), getClass().getClassLoader()); } catch (NamingException ex) { } //开启阻塞非守护进程 startDaemonAwaitThread(); } catch (Exception ex) { stopSilently(); destroySilently(); throw new WebServerException("Unable to start embedded Tomcat", ex); } }}//Tomcat.javapublic void start() throws LifecycleException { getServer(); server.start();}//这里server.start又会回到TomcatWebServer的public void stop() throws LifecycleException { getServer(); server.stop();}
//TomcatWebServer.java//启动tomcat服务@Overridepublic void start() throws WebServerException { synchronized (this.monitor) { if (this.started) { return; } try { addPreviouslyRemovedConnectors(); Connector connector = this.tomcat.getConnector(); if (connector != null && this.autoStart) { perfORMDeferredLoadOnStartup(); } checkThatConnectorsHaveStarted(); this.started = true; //在控制台打印这句日志,如果在yml设置了上下文,这里会打印 logger.info("Tomcat started on port(s): " + getPortsDescription(true) + " with context path '" + getContextPath() + "'"); } catch (ConnectorStartFailedException ex) { stopSilently(); throw ex; } catch (Exception ex) { throw new WebServerException("Unable to start embedded Tomcat server", ex); } finally { Context context = findContext(); ContextBindings.unbindClassLoader(context, context.getNamingToken(), getClass().getClassLoader()); } }}//关闭tomcat服务@Overridepublic void stop() throws WebServerException { synchronized (this.monitor) { boolean wasStarted = this.started; try { this.started = false; try { stopTomcat(); this.tomcat.destroy(); } catch (LifecycleException ex) { } } catch (Exception ex) { throw new WebServerException("Unable to stop embedded Tomcat", ex); } finally { if (wasStarted) { containerCounter.decrementAndGet(); } } }}
附:tomcat顶层结构图
tomcat最顶层容器是Server,代表着整个服务器,一个Server包含多个Service。从上图可以看除Service主要包括多个Connector和一个Container。Connector用来处理连接相关的事情,并提供Socket到Request和Response相关转化。Container用于封装和管理Servlet,以及处理具体的Request请求。那么上文提到的Engine>Host>Context>Wrapper容器又是怎么回事呢? 我们来看下图:
综上所述,一个tomcat只包含一个Server,一个Server可以包含多个Service,一个Service只有一个Container,但有多个Connector,这样一个服务可以处理多个连接。
多个Connector和一个Container就形成了一个Service,有了Service就可以对外提供服务了,但是Service要提供服务又必须提供一个宿主环境,那就非Server莫属了,所以整个tomcat的声明周期都由Server控制。
关于如何在SpringBoot中启动tomcat问题的解答就分享到这里了,希望以上内容可以对大家有一定的帮助,如果你还有很多疑惑没有解开,可以关注编程网精选频道了解更多相关知识。
--结束END--
本文标题: 如何在SpringBoot中启动tomcat
本文链接: https://www.lsjlt.com/news/275635.html(转载时请注明来源链接)
有问题或投稿请发送至: 邮箱/279061341@qq.com QQ/279061341
下载Word文档到电脑,方便收藏和打印~
2024-05-16
2024-05-16
2024-05-16
2024-05-16
2024-05-16
2024-05-16
2024-05-16
2024-05-16
2024-05-16
2024-05-16
回答
回答
回答
回答
回答
回答
回答
回答
回答
回答
0