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

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配置嵌入式Servlet容器

SpringBoot默认使用Tomcat作为嵌入式的Servlet容器;

问题?

1)、如何定制和修改Servlet容器的相关配置;

1、修改和server有关的配置(ServerProperties【也是EmbeddedServletContainerCustomizer】);

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

2、编写一个EmbeddedServletContainerCustomizer:嵌入式的Servlet容器的定制器;来修改Servlet容器的配置(1.x)

在Spring Boot2.0以上配置嵌入式Servlet容器时EmbeddedServletContainerCustomizer类不存在,被WebServerFactoryCustomizer替代。

1.x

@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);
 }
 };
}

2.x

@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);
 }
 };
}

2)、注册Servlet三大组件【Servlet、Filter、Listener】

由于SpringBoot默认是以jar包的方式启动嵌入式的Servlet容器来启动SpringBoot的web应用,没有web.xml文件。

注册三大组件用以下方式

ServletRegistrationBean

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

FilterRegistrationBean

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

ServletListenerRegistrationBean

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

SpringBoot帮我们自动SpringMVC的时候,自动的注册SpringMVC的前端控制器;DIspatcherServlet;

DispatcherServletAutoConfiguration中:

@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;
}

2)、SpringBoot能不能支持其他的Servlet容器;

3)、替换为其他嵌入式Servlet容器

默认支持:

Tomcat(默认使用)

<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>

Jetty

<!-- 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>

Undertow

<!-- 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>

4)、嵌入式Servlet容器自动配置原理;

SpringBoot2.X原理略有不同

由EmbeddedWebServerFactoryCustomizerAutoConfiguration(嵌入式web服务工厂定制器自动配置类)而不是EmbeddedServletContainerAutoConfiguration(嵌入式的Servlet容器自动配置),根据导入的依赖信息,该配置类会自动创建相应类型的容器工厂定制器(目前Spring Boot 2.x 版本支持tomcat、jetty、undertow、netty),以tomcat为例,这里会创建TomcatWebServerFactoryCustomizer组件:

@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);
 }
 }
 ...
}

1.X中通过EmbeddedServletContainerAutoConfiguration:嵌入式的Servlet容器自动配置类创建组件

@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();
		}
	}

1)、EmbeddedServletContainerFactory(嵌入式Servlet容器工厂)

public interface EmbeddedServletContainerFactory {

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

}

2)、EmbeddedServletContainer:(嵌入式的Servlet容器)

3)、以TomcatEmbeddedServletContainerFactory为例

@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);
}

4)、我们对嵌入式容器的配置修改是怎么生效?

ServerProperties、EmbeddedServletContainerCustomizer

EmbeddedServletContainerCustomizer:定制器帮我们修改了Servlet容器的配置?

怎么修改的原理?

5)、容器中导入了EmbeddedServletContainerCustomizerBeanPostProcessor

//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

步骤:

1)、SpringBoot根据导入的依赖情况,给容器中添加相应的EmbeddedServletContainerFactory【TomcatEmbeddedServletContainerFactory】

2)、容器中某个组件要创建对象就会惊动后置处理器;EmbeddedServletContainerCustomizerBeanPostProcessor;

只要是嵌入式的Servlet容器工厂,后置处理器就工作;

3)、后置处理器,从容器中获取所有的EmbeddedServletContainerCustomizer,调用定制器的定制方法

5)、嵌入式Servlet容器启动原理;

什么时候创建嵌入式的Servlet容器工厂?什么时候获取嵌入式的Servlet容器并启动Tomcat;

获取嵌入式的Servlet容器工厂:

1)、SpringBoot应用启动运行run方法

2)、refreshContext(context);SpringBoot刷新IOC容器【创建IOC容器对象,并初始化容器,创建容器中的每一个组件】;如果是web应用创建AnnotationConfigEmbeddedWebApplicationContext,否则:AnnotationConfigApplicationContext

3)、refresh(context);刷新刚才创建好的ioc容器;

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();
 }
 }
}

4)、 onRefresh(); web的ioc容器重写了onRefresh方法

5)、webioc容器会创建嵌入式的Servlet容器;createEmbeddedServletContainer();

6)、获取嵌入式的Servlet容器工厂:

EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();

​从ioc容器中获取EmbeddedServletContainerFactory 组件;TomcatEmbeddedServletContainerFactory创建对象,后置处理器一看是这个对象,就获取所有的定制器来先定制Servlet容器的相关配置;

7)、使用容器工厂获取嵌入式的Servlet容器:this.embeddedServletContainer = containerFactory .getEmbeddedServletContainer(getSelfInitializer());

8)、嵌入式的Servlet容器创建对象并启动Servlet容器;

先启动嵌入式的Servlet容器,再将ioc容器中剩下没有创建出的对象获取出来;

IOC容器启动创建嵌入式的Servlet容器

使用外置的Servlet容器

嵌入式Servlet容器:应用打成可执行的jar

​优点:简单、便携;

​缺点:默认不支持JSP、优化定制比较复杂(使用定制器【ServerProperties、自定义EmbeddedServletContainerCustomizer】,自己编写嵌入式Servlet容器的创建工厂【EmbeddedServletContainerFactory】);

外置的Servlet容器:外面安装Tomcat---应用war包的方式打包;

步骤

1)、必须创建一个war项目;(利用idea创建好目录结构)

2)、将嵌入式的Tomcat指定为provided;

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

3)、必须编写一个SpringBootServletInitializer的子类,并调用configure方法

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);
 }

}

4)、启动服务器就可以使用;

原理

jar包:执行SpringBoot主类的main方法,启动ioc容器,创建嵌入式的Servlet容器;

war包:启动服务器,服务器启动SpringBoot应用【SpringBootServletInitializer】,启动ioc容器;

servlet3.0(Spring注解版):

8.2.4 Shared libraries / runtimes pluggability:

规则:

​1)、服务器启动(web应用启动)会创建当前web应用里面每一个jar包里面ServletContainerInitializer实例:

​2)、ServletContainerInitializer的实现放在jar包的META-INF/services文件夹下,有一个名为javax.servlet.ServletContainerInitializer的文件,内容就是ServletContainerInitializer的实现类的全类名

​3)、还可以使用@HandlesTypes,在应用启动的时候加载我们感兴趣的类;

流程:

1)、启动Tomcat

2)、org\springframework\spring-web\4.3.14.RELEASE\spring-web-4.3.14.RELEASE.jar!\META-INF\services\javax.servlet.ServletContainerInitializer:

Spring的web模块里面有这个文件:org.springframework.web.SpringServletContainerInitializer

3)、SpringServletContainerInitializer将@HandlesTypes(WebApplicationInitializer.class)标注的所有这个类型的类都传入到onStartup方法的Set<Class<?>>;为这些WebApplicationInitializer类型的类创建实例;

4)、每一个WebApplicationInitializer都调用自己的onStartup;

5)、相当于我们的SpringBootServletInitializer的类会被创建对象,并执行onStartup方法

6)、SpringBootServletInitializer实例执行onStartup的时候会createRootApplicationContext;创建容器

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);
}

7)、Spring的应用就启动并且创建IOC容器

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);
 }
}

启动Servlet容器,再启动SpringBoot应用

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