Add Undertow WebSocket auto-configuration

Fixes gh-2028

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/websocket/UndertowWebSocketContainerCustomizer.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-2014 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.websocket;
+
+import io.undertow.servlet.api.DeploymentInfo;
+import io.undertow.websockets.jsr.WebSocketDeploymentInfo;
+
+import org.springframework.boot.context.embedded.undertow.UndertowDeploymentInfoCustomizer;
+import org.springframework.boot.context.embedded.undertow.UndertowEmbeddedServletContainerFactory;
+
+/**
+ * {@link WebSocketContainerCustomizer} for
+ * {@link UndertowEmbeddedServletContainerFactory}.
+ *
+ * @author Phillip Webb
+ * @since 1.2.0
+ */
+public class UndertowWebSocketContainerCustomizer extends
+		WebSocketContainerCustomizer<UndertowEmbeddedServletContainerFactory> {
+
+	@Override
+	protected void doCustomize(UndertowEmbeddedServletContainerFactory container) {
+		WebsocketDeploymentInfoCustomizer customizer = new WebsocketDeploymentInfoCustomizer();
+		container.addDeploymentInfoCustomizers(customizer);
+	}
+
+	private static class WebsocketDeploymentInfoCustomizer implements
+			UndertowDeploymentInfoCustomizer {
+
+		@Override
+		public void customize(DeploymentInfo deploymentInfo) {
+			WebSocketDeploymentInfo info = new WebSocketDeploymentInfo();
+			deploymentInfo.addServletContextAttribute(
+					WebSocketDeploymentInfo.ATTRIBUTE_NAME, info);
+		}
+
+	}
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/websocket/WebSocketAutoConfiguration.java

@@ -75,4 +75,16 @@ public class WebSocketAutoConfiguration {
 
 	}
 
+	@Configuration
+	@ConditionalOnClass(io.undertow.websockets.jsr.Bootstrap.class)
+	static class UndertowWebSocketConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(name = "websocketContainerCustomizer")
+		public EmbeddedServletContainerCustomizer websocketContainerCustomizer() {
+			return new UndertowWebSocketContainerCustomizer();
+		}
+
+	}
+
 }