SpringBoot配置嵌入式Servlet容器和使用外置Servlet容器的教程图解

server.port=8081
server.context-path=/crud

server.tomcat.uri-encoding=UTF-8

//通用的Servlet容器设置
server.xxx
//Tomcat的设置
server.tomcat.xxx

@Bean //一定要将这个定制器加入到容器中
public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
 return new WebServerFactoryCustomizer<ConfigurableWebServerFactory> {

 //定制嵌入式的Servlet容器相关的规则
 @Override
 public void customize(ConfigurableWebServerFactory factory) {
  container.setPort(8083);
 }
 };
}

@Bean //一定要将这个定制器加入到容器中
public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
 return new EmbeddedServletContainerCustomizer() {
 
 //定制嵌入式的Servlet容器相关的规则
 @Override
 public void customize(ConfigurableEmbeddedServletContainer container) {
  container.setPort(8083);
 }
 };
}

//注册三大组件
@Bean
public ServletRegistrationBean myServlet(){
 ServletRegistrationBean registrationBean = new ServletRegistrationBean(new MyServlet(),"/myServlet");
 return registrationBean;
}

@Bean
public FilterRegistrationBean myFilter(){
 FilterRegistrationBean registrationBean = new FilterRegistrationBean();
 registrationBean.setFilter(new MyFilter());
 registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));
 return registrationBean;
}

@Bean
public ServletListenerRegistrationBean myListener(){
 ServletListenerRegistrationBean<MyListener> registrationBean = new ServletListenerRegistrationBean<>(new MyListener());
 return registrationBean;
}

@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public ServletRegistrationBean dispatcherServletRegistration(
 DispatcherServlet dispatcherServlet) {
 ServletRegistrationBean registration = new ServletRegistrationBean(
  dispatcherServlet, this.serverProperties.getServletMapping());
 //默认拦截： / 所有请求；包静态资源，但是不拦截jsp请求； /*会拦截jsp
 //可以通过server.servletPath来修改SpringMVC前端控制器默认拦截的请求路径
 
 registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
 registration.setLoadOnStartup(
  this.webMvcProperties.getServlet().getLoadOnStartup());
 if (this.multipartConfig != null) {
 registration.setMultipartConfig(this.multipartConfig);
 }
 return registration;
}

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
 引入web模块默认就是使用嵌入式的Tomcat作为Servlet容器；
</dependency>

<!-- 引入web模块 -->
<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
 <exclusions>
 <exclusion>
  <artifactId>spring-boot-starter-tomcat</artifactId>
  <groupId>org.springframework.boot</groupId>
 </exclusion>
 </exclusions>
</dependency>

<!--引入其他的Servlet容器-->
<dependency>
 <artifactId>spring-boot-starter-jetty</artifactId>
 <groupId>org.springframework.boot</groupId>
</dependency>

<!-- 引入web模块 -->
<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
 <exclusions>
 <exclusion>
  <artifactId>spring-boot-starter-tomcat</artifactId>
  <groupId>org.springframework.boot</groupId>
 </exclusion>
 </exclusions>
</dependency>

<!--引入其他的Servlet容器-->
<dependency>
 <artifactId>spring-boot-starter-undertow</artifactId>
 <groupId>org.springframework.boot</groupId>
</dependency>

@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication
//指定类ServerProperties（Servlet容器相关的配置类）中的ConfigurationProperties功能，将配置文件中对应的属性值与配置类中的属性值进行映射，并将该配置类添加到IOC容器中
@EnableConfigurationProperties(ServerProperties.class)
public class EmbeddedWebServerFactoryCustomizerAutoConfiguration {

	/**
	 * Nested configuration if Tomcat is being used.
	 */
 @Configuration(proxyBeanMethods = false)
 //导入的Servlet依赖为Tomcat，则创建Tomcat web服务工厂定制器
 @ConditionalOnClass({ Tomcat.class, UpgradeProtocol.class })
 public static class TomcatWebServerFactoryCustomizerConfiguration {

 @Bean
 public TomcatWebServerFactoryCustomizer tomcatWebServerFactoryCustomizer(Environment 				environment,ServerProperties serverProperties) {
  return new TomcatWebServerFactoryCustomizer(environment, serverProperties);
 }
 }
 ...
}

@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//导入BeanPostProcessorsRegistrar：Spring注解版；给容器中导入一些组件
//导入了EmbeddedServletContainerCustomizerBeanPostProcessor：
//后置处理器：bean初始化前后（创建完对象，还没赋值赋值）执行初始化工作
public class EmbeddedServletContainerAutoConfiguration {
 
 @Configuration
	@ConditionalOnClass({ Servlet.class, Tomcat.class })//判断当前是否引入了Tomcat依赖；
	@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)//判断当前容器没有用户自己定义EmbeddedServletContainerFactory：嵌入式的Servlet容器工厂；作用：创建嵌入式的Servlet容器
	public static class EmbeddedTomcat {

		@Bean
		public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
			return new TomcatEmbeddedServletContainerFactory();
		}

	}
 
 /**
	 * Nested configuration if Jetty is being used.
	 */
	@Configuration
	@ConditionalOnClass({ Servlet.class, Server.class, Loader.class,
			WebAppContext.class })
	@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
	public static class EmbeddedJetty {

		@Bean
		public JettyEmbeddedServletContainerFactory jettyEmbeddedServletContainerFactory() {
			return new JettyEmbeddedServletContainerFactory();
		}

	}

	/**
	 * Nested configuration if Undertow is being used.
	 */
	@Configuration
	@ConditionalOnClass({ Servlet.class, Undertow.class, SslClientAuthMode.class })
	@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
	public static class EmbeddedUndertow {

		@Bean
		public UndertowEmbeddedServletContainerFactory undertowEmbeddedServletContainerFactory() {
			return new UndertowEmbeddedServletContainerFactory();
		}
	}

public interface EmbeddedServletContainerFactory {

 //获取嵌入式的Servlet容器
 EmbeddedServletContainer getEmbeddedServletContainer(
  ServletContextInitializer... initializers);

}

@Override
public EmbeddedServletContainer getEmbeddedServletContainer(
 ServletContextInitializer... initializers) {
 //创建一个Tomcat
 Tomcat tomcat = new Tomcat();
 
 //配置Tomcat的基本环节
 File baseDir = (this.baseDirectory != null ? this.baseDirectory
  : createTempDir("tomcat"));
 tomcat.setBaseDir(baseDir.getAbsolutePath());
 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);
 
 //将配置好的Tomcat传入进去，返回一个EmbeddedServletContainer；并且启动Tomcat服务器
 return getTomcatEmbeddedServletContainer(tomcat);
}

//初始化之前
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
 throws BeansException {
 //如果当前初始化的是一个ConfigurableEmbeddedServletContainer类型的组件
 if (bean instanceof ConfigurableEmbeddedServletContainer) {
 //
 postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
 }
 return bean;
}

private void postProcessBeforeInitialization(
			ConfigurableEmbeddedServletContainer bean) {
 //获取所有的定制器，调用每一个定制器的customize方法来给Servlet容器进行属性赋值；
 for (EmbeddedServletContainerCustomizer customizer : getCustomizers()) {
 customizer.customize(bean);
 }
}

private Collection<EmbeddedServletContainerCustomizer> getCustomizers() {
 if (this.customizers == null) {
 // Look up does not include the parent context
 this.customizers = new ArrayList<EmbeddedServletContainerCustomizer>(
  this.beanFactory
  //从容器中获取所有这葛类型的组件：EmbeddedServletContainerCustomizer
  //定制Servlet容器，给容器中可以添加一个EmbeddedServletContainerCustomizer类型的组件
  .getBeansOfType(EmbeddedServletContainerCustomizer.class,
    false, false)
  .values());
 Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
 this.customizers = Collections.unmodifiableList(this.customizers);
 }
 return this.customizers;
}

ServerProperties也是定制器

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();
 }

 catch (BeansException ex) {
  if (logger.isWarnEnabled()) {
  logger.warn("Exception encountered during context initialization - " +
   "cancelling refresh attempt: " + ex);
  }

  // Destroy already created singletons to avoid dangling resources.
  destroyBeans();

  // Reset 'active' flag.
  cancelRefresh(ex);

  // Propagate exception to caller.
  throw ex;
 }

 finally {
  // Reset common introspection caches in Spring's core, since we
  // might not ever need metadata for singleton beans anymore...
  resetCommonCaches();
 }
 }
}

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-tomcat</artifactId>
 <scope>provided</scope>
</dependency>

public class ServletInitializer extends SpringBootServletInitializer {

 @Override
 protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
 //传入SpringBoot应用的主程序
 return application.sources(SpringBoot04WebJspApplication.class);
 }

}

protected WebApplicationContext createRootApplicationContext(
 ServletContext servletContext) {
 //1、创建SpringApplicationBuilder
 SpringApplicationBuilder builder = createSpringApplicationBuilder();
 StandardServletEnvironment environment = new StandardServletEnvironment();
 environment.initPropertySources(servletContext, null);
 builder.environment(environment);
 builder.main(getClass());
 ApplicationContext parent = getExistingRootWebApplicationContext(servletContext);
 if (parent != null) {
 this.logger.info("Root context already created (using as parent).");
 servletContext.setAttribute(
  WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, null);
 builder.initializers(new ParentContextApplicationContextInitializer(parent));
 }
 builder.initializers(
  new ServletContextApplicationContextInitializer(servletContext));
 builder.contextClass(AnnotationConfigEmbeddedWebApplicationContext.class);
 
 //调用configure方法，子类重写了这个方法，将SpringBoot的主程序类传入了进来
 builder = configure(builder);
 
 //使用builder创建一个Spring应用
 SpringApplication application = builder.build();
 if (application.getSources().isEmpty() && AnnotationUtils
  .findAnnotation(getClass(), Configuration.class) != null) {
 application.getSources().add(getClass());
 }
 Assert.state(!application.getSources().isEmpty(),
  "No SpringApplication sources have been defined. Either override the "
  + "configure method or add an @Configuration annotation");
 // Ensure error pages are registered
 if (this.registerErrorPageFilter) {
 application.getSources().add(ErrorPageFilterConfiguration.class);
 }
 //启动Spring应用
 return run(application);
}

public ConfigurableApplicationContext run(String... args) {
 StopWatch stopWatch = new StopWatch();
 stopWatch.start();
 ConfigurableApplicationContext context = null;
 FailureAnalyzers analyzers = null;
 configureHeadlessProperty();
 SpringApplicationRunListeners listeners = getRunListeners(args);
 listeners.starting();
 try {
 ApplicationArguments applicationArguments = new DefaultApplicationArguments(
  args);
 ConfigurableEnvironment environment = prepareEnvironment(listeners,
  applicationArguments);
 Banner printedBanner = printBanner(environment);
 context = createApplicationContext();
 analyzers = new FailureAnalyzers(context);
 prepareContext(context, environment, listeners, applicationArguments,
  printedBanner);
 
 //刷新IOC容器
 refreshContext(context);
 afterRefresh(context, applicationArguments);
 listeners.finished(context, null);
 stopWatch.stop();
 if (this.logStartupInfo) {
  new StartupInfoLogger(this.mainApplicationClass)
  .logStarted(getApplicationLog(), stopWatch);
 }
 return context;
 }
 catch (Throwable ex) {
 handleRunFailure(context, listeners, analyzers, ex);
 throw new IllegalStateException(ex);
 }
}