springboot配置嵌入式Servlet容器

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

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(newMyServlet(),"/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>

@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);
}

ServerProperties、EmbeddedServletContainerCustomizer

//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;
}

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