@EnableWebFlux setup supports WebSocketHandler

Closes gh-22587

spring-webflux/src/main/java/org/springframework/web/reactive/config/DelegatingWebFluxConfiguration.java

@@ -27,6 +27,7 @@ import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolverBuilder;
 import org.springframework.web.reactive.result.method.annotation.ArgumentResolverConfigurer;
+import org.springframework.web.reactive.socket.server.WebSocketService;
 
 /**
  * A subclass of {@code WebFluxConfigurationSupport} that detects and delegates
@@ -98,6 +99,12 @@ public class DelegatingWebFluxConfiguration extends WebFluxConfigurationSupport
 		return (messageCodesResolver != null ? messageCodesResolver : super.getMessageCodesResolver());
 	}
 
+	@Override
+	protected WebSocketService getWebSocketService() {
+		WebSocketService service = this.configurers.getWebSocketService();
+		return (service != null ? service : super.getWebSocketService());
+	}
+
 	@Override
 	protected void configureViewResolvers(ViewResolverRegistry registry) {
 		this.configurers.configureViewResolvers(registry);

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurationSupport.java

@@ -65,6 +65,8 @@ import org.springframework.web.reactive.result.method.annotation.ResponseBodyRes
 import org.springframework.web.reactive.result.method.annotation.ResponseEntityResultHandler;
 import org.springframework.web.reactive.result.view.ViewResolutionResultHandler;
 import org.springframework.web.reactive.result.view.ViewResolver;
+import org.springframework.web.reactive.socket.server.WebSocketService;
+import org.springframework.web.reactive.socket.server.support.WebSocketHandlerAdapter;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebExceptionHandler;
 import org.springframework.web.server.i18n.AcceptHeaderLocaleContextResolver;
@@ -431,6 +433,24 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 		return new SimpleHandlerAdapter();
 	}
 
+	@Bean
+	public WebSocketHandlerAdapter webFluxWebSocketHandlerAdapter() {
+		WebSocketService service = getWebSocketService();
+		WebSocketHandlerAdapter adapter = (service != null ?
+				new WebSocketHandlerAdapter(service) : new WebSocketHandlerAdapter());
+
+		// For backwards compatibility, lower the (default) priority
+		int defaultOrder = adapter.getOrder();
+		adapter.setOrder(defaultOrder + 1);
+
+		return adapter;
+	}
+
+	@Nullable
+	protected WebSocketService getWebSocketService() {
+		return null;
+	}
+
 	@Bean
 	public ResponseEntityResultHandler responseEntityResultHandler(
 			@Qualifier("webFluxAdapterRegistry") ReactiveAdapterRegistry reactiveAdapterRegistry,

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolverBuilder;
 import org.springframework.web.reactive.result.method.annotation.ArgumentResolverConfigurer;
+import org.springframework.web.reactive.socket.server.WebSocketService;
 
 /**
  * Defines callback methods to customize the configuration for WebFlux
@@ -124,6 +125,18 @@ public interface WebFluxConfigurer {
 		return null;
 	}
 
+	/**
+	 * Provide the {@link WebSocketService} to create
+	 * {@link org.springframework.web.reactive.socket.server.support.WebSocketHandlerAdapter}
+	 * with. This can be used to configure server-specific properties through the
+	 * {@link org.springframework.web.reactive.socket.server.RequestUpgradeStrategy}.
+	 * @since 5.3
+	 */
+	@Nullable
+	default WebSocketService getWebSocketService() {
+		return null;
+	}
+
 	/**
 	 * Configure view resolution for rendering responses with a view and a model,
 	 * where the view is typically an HTML template but could also be based on

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurerComposite.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,7 @@ import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolverBuilder;
 import org.springframework.web.reactive.result.method.annotation.ArgumentResolverConfigurer;
+import org.springframework.web.reactive.socket.server.WebSocketService;
 
 /**
  * A {@link WebFluxConfigurer} that delegates to one or more others.
@@ -70,6 +71,12 @@ public class WebFluxConfigurerComposite implements WebFluxConfigurer {
 		this.delegates.forEach(delegate -> delegate.addResourceHandlers(registry));
 	}
 
+	@Nullable
+	@Override
+	public WebSocketService getWebSocketService() {
+		return createSingleBean(WebFluxConfigurer::getWebSocketService, WebSocketService.class);
+	}
+
 	@Override
 	public void configureArgumentResolvers(ArgumentResolverConfigurer configurer) {
 		this.delegates.forEach(delegate -> delegate.configureArgumentResolvers(configurer));

spring-webflux/src/main/java/org/springframework/web/reactive/socket/server/support/WebSocketHandlerAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,8 +17,8 @@ package org.springframework.web.reactive.socket.server.support;
 
 import reactor.core.publisher.Mono;
 
+import org.springframework.core.Ordered;
 import org.springframework.util.Assert;
-import org.springframework.web.reactive.DispatcherHandler;
 import org.springframework.web.reactive.HandlerAdapter;
 import org.springframework.web.reactive.HandlerResult;
 import org.springframework.web.reactive.socket.WebSocketHandler;
@@ -26,18 +26,30 @@ import org.springframework.web.reactive.socket.server.WebSocketService;
 import org.springframework.web.server.ServerWebExchange;
 
 /**
- * {@link HandlerAdapter} that allows using a {@link WebSocketHandler} with the
- * generic {@link DispatcherHandler} mapping URLs directly to such handlers.
- * Requests are handled by delegating to the configured {@link WebSocketService}
- * which by default is {@link HandshakeWebSocketService}.
+ * {@code HandlerAdapter} that allows
+ * {@link org.springframework.web.reactive.DispatcherHandler} to support
+ * handlers of type {@link WebSocketHandler} with such handlers mapped to
+ * URL patterns via
+ * {@link org.springframework.web.reactive.handler.SimpleUrlHandlerMapping}.
+ *
+ * <p>Requests are handled by delegating to a
+ * {@link WebSocketService}, by default {@link HandshakeWebSocketService},
+ * which checks the WebSocket handshake request parameters, upgrades to a
+ * WebSocket interaction, and uses the {@link WebSocketHandler} to handle it.
+ *
+ * <p>As of 5.3 the WebFlux Java configuration, imported via
+ * {@code @EnableWebFlux}, includes a declaration of this adapter and therefore
+ * it no longer needs to be present in application configuration.
  *
  * @author Rossen Stoyanchev
  * @since 5.0
  */
-public class WebSocketHandlerAdapter implements HandlerAdapter {
+public class WebSocketHandlerAdapter implements HandlerAdapter, Ordered {
 
 	private final WebSocketService webSocketService;
 
+	private int order = 2;
+
 
 	/**
 	 * Default constructor that creates and uses a
@@ -56,6 +68,25 @@ public class WebSocketHandlerAdapter implements HandlerAdapter {
 	}
 
 
+	/**
+	 * Set the order value for this adapter.
+	 * <p>By default this is set to 2.
+	 * @param order the value to set to
+	 * @since 5.3
+	 */
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	/**
+	 * Return the {@link #setOrder(int) configured} order for this instance.
+	 * @since 5.3
+	 */
+	@Override
+	public int getOrder() {
+		return this.order;
+	}
+
 	/**
 	 * Return the configured {@code WebSocketService} to handle requests.
 	 */