Add load-on-startup property to DispatcherServlet

Closes gh-2481

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

@@ -110,6 +110,8 @@ public class DispatcherServletAutoConfiguration {
 			ServletRegistrationBean registration = new ServletRegistrationBean(
 					dispatcherServlet(), this.server.getServletMapping());
 			registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
+			registration.setLoadOnStartup(
+					this.webMvcProperties.getServlet().getLoadOnStartup());
 			if (this.multipartConfig != null) {
 				registration.setMultipartConfig(this.multipartConfig);
 			}

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

@@ -84,6 +84,8 @@ public class WebMvcProperties {
 
 	private final Async async = new Async();
 
+	private final Servlet servlet = new Servlet();
+
 	private final View view = new View();
 
 	public DefaultMessageCodesResolver.Format getMessageCodesResolverFormat() {
@@ -164,6 +166,10 @@ public class WebMvcProperties {
 		return this.async;
 	}
 
+	public Servlet getServlet() {
+		return this.servlet;
+	}
+
 	public View getView() {
 		return this.view;
 	}
@@ -187,6 +193,23 @@ public class WebMvcProperties {
 
 	}
 
+	public static class Servlet {
+
+		/**
+		 * Load on startup priority of the dispatcher servlet.
+		 */
+		private int loadOnStartup = -1;
+
+		public int getLoadOnStartup() {
+			return this.loadOnStartup;
+		}
+
+		public void setLoadOnStartup(int loadOnStartup) {
+			this.loadOnStartup = loadOnStartup;
+		}
+
+	}
+
 	public static class View {
 
 		/**

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/DispatcherServletAutoConfigurationTests.java

@@ -22,6 +22,7 @@ import javax.servlet.http.HttpServletRequest;
 import org.junit.After;
 import org.junit.Test;
 
+import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.beans.factory.UnsatisfiedDependencyException;
 import org.springframework.boot.test.util.EnvironmentTestUtils;
 import org.springframework.boot.web.servlet.MultipartConfigFactory;
@@ -151,17 +152,19 @@ public class DispatcherServletAutoConfigurationTests {
 		this.context.register(ServerPropertiesAutoConfiguration.class,
 				DispatcherServletAutoConfiguration.class);
 		EnvironmentTestUtils.addEnvironment(this.context,
-				"spring.mvc.throw-exception-if-no-handler-found:true");
-		EnvironmentTestUtils.addEnvironment(this.context,
-				"spring.mvc.dispatch-options-request:true");
-		EnvironmentTestUtils.addEnvironment(this.context,
-				"spring.mvc.dispatch-trace-request:true");
+				"spring.mvc.throw-exception-if-no-handler-found:true",
+				"spring.mvc.dispatch-options-request:true",
+				"spring.mvc.dispatch-trace-request:true",
+				"spring.mvc.servlet.load-on-startup=5");
 		this.context.refresh();
 		DispatcherServlet bean = this.context.getBean(DispatcherServlet.class);
 		assertThat(bean).extracting("throwExceptionIfNoHandlerFound")
 				.containsExactly(true);
 		assertThat(bean).extracting("dispatchOptionsRequest").containsExactly(true);
 		assertThat(bean).extracting("dispatchTraceRequest").containsExactly(true);
+		assertThat(
+				new DirectFieldAccessor(this.context.getBean("dispatcherServletRegistration"))
+						.getPropertyValue("loadOnStartup")).isEqualTo(5);
 	}
 
 	@Configuration

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -337,6 +337,7 @@ content into your application; rather pick only the properties that you need.
 	spring.mvc.locale= # Locale to use.
 	spring.mvc.media-types.*= # Maps file extensions to media types for content negotiation.
 	spring.mvc.message-codes-resolver-format= # Formatting strategy for message codes. For instance `PREFIX_ERROR_CODE`.
+	spring.mvc.servlet.load-on-startup=-1 # Load on startup priority of the Spring Web Services servlet.
 	spring.mvc.static-path-pattern=/** # Path pattern used for static resources.
 	spring.mvc.throw-exception-if-no-handler-found=false # If a "NoHandlerFoundException" should be thrown if no Handler was found to process a request.
 	spring.mvc.view.prefix= # Spring MVC view prefix.