WebFlux的初始化流程

@EnableWebFlux

先看@EnableWebFlux的定义：

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebFluxConfiguration.class)
public @interface EnableWebFlux {
}

这里引入的是DelegatingWebFluxConfiguration，如下：

@Configuration(proxyBeanMethods = false)
public class DelegatingWebFluxConfiguration extends WebFluxConfigurationSupport {
  
  

继承于WebFluxConfigurationSupport：

public class WebFluxConfigurationSupport implements ApplicationContextAware {
    
    @Bean
	public DispatcherHandler webHandler() {
		return new DispatcherHandler();
	}

}

可以看出这里引入了DispatcherHandler，对应beanName为webHandler

WebApplicationInitializer

这里对应的实现类为

public abstract class AbstractReactiveWebInitializer implements WebApplicationInitializer {
    
@Override
	public void onStartup(ServletContext servletContext) throws ServletException {
		String servletName = getServletName();
		Assert.hasLength(servletName, "getServletName() must not return null or empty");

		ApplicationContext applicationContext = createApplicationContext();
		Assert.notNull(applicationContext, "createApplicationContext() must not return null");

		refreshApplicationContext(applicationContext);
		registerCloseListener(servletContext, applicationContext);

		HttpHandler httpHandler = WebHttpHandlerBuilder.applicationContext(applicationContext).build();
		ServletHttpHandlerAdapter servlet = new ServletHttpHandlerAdapter(httpHandler);

		ServletRegistration.Dynamic registration = servletContext.addServlet(servletName, servlet);
		if (registration == null) {
			throw new IllegalStateException("Failed to register servlet with name '" + servletName + "'. " +
					"Check if there is another servlet registered under the same name.");
		}

		registration.setLoadOnStartup(1);
		registration.addMapping(getServletMapping());
		registration.setAsyncSupported(true);
	}

}

可以看出这里注册的servlet为ServletHttpHandlerAdapter，核心方法为service：

	public void service(ServletRequest request, Ser