Enable Tomcat to use HTTP/2

Author: pvorb

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/DefaultServletWebServerFactoryCustomizer.java

@@ -29,6 +29,7 @@
 import org.apache.coyote.AbstractProtocol;
 import org.apache.coyote.ProtocolHandler;
 import org.apache.coyote.http11.AbstractHttp11Protocol;
+import org.apache.coyote.http2.Http2Protocol;
 import org.eclipse.jetty.server.AbstractConnector;
 import org.eclipse.jetty.server.ConnectionFactory;
 import org.eclipse.jetty.server.Handler;
@@ -46,6 +47,7 @@
 import org.springframework.boot.web.embedded.jetty.JettyServletWebServerFactory;
 import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
 import org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory;
+import org.springframework.boot.web.server.Http2;
 import org.springframework.boot.web.server.WebServerFactoryCustomizer;
 import org.springframework.boot.web.servlet.ServletContextInitializer;
 import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
@@ -213,6 +215,8 @@ private static class TomcatCustomizer {
 		public static void customizeTomcat(ServerProperties serverProperties,
 				Environment environment, TomcatServletWebServerFactory factory) {
 
+			customizeTomcatHttp2(factory, serverProperties);
+
 			ServerProperties.Tomcat tomcatProperties = serverProperties.getTomcat();
 			if (tomcatProperties.getBasedir() != null) {
 				factory.setBaseDirectory(tomcatProperties.getBasedir());
@@ -261,6 +265,20 @@ public static void customizeTomcat(ServerProperties serverProperties,
 			}
 		}
 
+		private static void customizeTomcatHttp2(TomcatServletWebServerFactory factory,
+				ServerProperties serverProperties) {
+
+			Http2 http2Properties = serverProperties.getHttp2();
+
+			if (http2Properties.isEnabled()) {
+				enableTomcatHttp2(factory);
+			}
+		}
+
+		private static void enableTomcatHttp2(TomcatServletWebServerFactory factory) {
+			factory.addConnectorCustomizers(connector -> connector.addUpgradeProtocol(new Http2Protocol()));
+		}
+
 		private static void customizeAcceptCount(TomcatServletWebServerFactory factory,
 				final int acceptCount) {
 			factory.addConnectorCustomizers((connector) -> {