Hide default SockJS TaskScheduler for @EnableWebSocket

Closes gh-27903

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/WebSocketConfigurationSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.web.socket.config.annotation;
 
+import org.springframework.beans.factory.DisposableBean;
+import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.lang.Nullable;
 import org.springframework.scheduling.TaskScheduler;
@@ -35,16 +37,13 @@ public class WebSocketConfigurationSupport {
 	@Nullable
 	private ServletWebSocketHandlerRegistry handlerRegistry;
 
-	@Nullable
-	private TaskScheduler scheduler;
-
 
 	@Bean
-	public HandlerMapping webSocketHandlerMapping(@Nullable TaskScheduler defaultSockJsTaskScheduler) {
+	public HandlerMapping webSocketHandlerMapping(DefaultSockJsSchedulerContainer schedulerContainer) {
 		ServletWebSocketHandlerRegistry registry = initHandlerRegistry();
 		if (registry.requiresTaskScheduler()) {
-			TaskScheduler scheduler = defaultSockJsTaskScheduler;
-			Assert.notNull(scheduler, "Expected default TaskScheduler bean");
+			TaskScheduler scheduler = schedulerContainer.getScheduler();
+			Assert.notNull(scheduler, "TaskScheduler is required but not initialized");
 			registry.setTaskScheduler(scheduler);
 		}
 		return registry.getHandlerMapping();
@@ -62,8 +61,9 @@ public class WebSocketConfigurationSupport {
 	}
 
 	/**
-	 * The default TaskScheduler to use if none is registered explicitly via
-	 * {@link SockJsServiceRegistration#setTaskScheduler}:
+	 * A container of the default TaskScheduler to use if none was registered
+	 * explicitly via {@link SockJsServiceRegistration#setTaskScheduler} as
+	 * follows:
 	 * <pre class="code">
 	 * &#064;Configuration
 	 * &#064;EnableWebSocket
@@ -80,16 +80,50 @@ public class WebSocketConfigurationSupport {
 	 * </pre>
 	 */
 	@Bean
-	@Nullable
-	public TaskScheduler defaultSockJsTaskScheduler() {
-		if (initHandlerRegistry().requiresTaskScheduler()) {
-			ThreadPoolTaskScheduler threadPoolScheduler = new ThreadPoolTaskScheduler();
-			threadPoolScheduler.setThreadNamePrefix("SockJS-");
-			threadPoolScheduler.setPoolSize(Runtime.getRuntime().availableProcessors());
-			threadPoolScheduler.setRemoveOnCancelPolicy(true);
-			this.scheduler = threadPoolScheduler;
-		}
-		return this.scheduler;
+	public DefaultSockJsSchedulerContainer defaultSockJsSchedulerContainer() {
+		return (initHandlerRegistry().requiresTaskScheduler() ?
+				new DefaultSockJsSchedulerContainer(initDefaultSockJsScheduler()) :
+				new DefaultSockJsSchedulerContainer(null));
 	}
 
+	private ThreadPoolTaskScheduler initDefaultSockJsScheduler() {
+		ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
+		scheduler.setThreadNamePrefix("SockJS-");
+		scheduler.setPoolSize(Runtime.getRuntime().availableProcessors());
+		scheduler.setRemoveOnCancelPolicy(true);
+		return scheduler;
+	}
+
+
+	private static class DefaultSockJsSchedulerContainer implements InitializingBean, DisposableBean {
+
+		@Nullable
+		private final ThreadPoolTaskScheduler scheduler;
+
+		DefaultSockJsSchedulerContainer(@Nullable ThreadPoolTaskScheduler scheduler) {
+			this.scheduler = scheduler;
+		}
+
+		@Nullable
+		public ThreadPoolTaskScheduler getScheduler() {
+			return this.scheduler;
+		}
+
+		@Override
+		public void afterPropertiesSet() throws Exception {
+			if (this.scheduler != null) {
+				this.scheduler.afterPropertiesSet();
+			}
+		}
+
+		@Override
+		public void destroy() throws Exception {
+			if (this.scheduler != null) {
+				this.scheduler.destroy();
+			}
+		}
+
+	}
+
+
 }