Add MultipartConfig to DispatcherServlet by default

RC4 added a ServletRegistrationBaen for teh DispatcherServlet and we
didn't register a MultipartConfigElement if one was present.

Fixes gh-427

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

@@ -19,6 +19,7 @@ package org.springframework.boot.autoconfigure.web;
 import java.util.Arrays;
 import java.util.List;
 
+import javax.servlet.MultipartConfigElement;
 import javax.servlet.ServletRegistration;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -69,6 +70,9 @@ public class DispatcherServletAutoConfiguration {
 		@Autowired
 		private ServerProperties server;
 
+		@Autowired(required = false)
+		private MultipartConfigElement multipartConfig;
+
 		@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
 		public DispatcherServlet dispatcherServlet() {
 			return new DispatcherServlet();
@@ -76,8 +80,12 @@ public class DispatcherServletAutoConfiguration {
 
 		@Bean
 		public ServletRegistrationBean dispatcherServletRegistration() {
-			return new ServletRegistrationBean(dispatcherServlet(),
-					this.server.getServletPath());
+			ServletRegistrationBean registration = new ServletRegistrationBean(
+					dispatcherServlet(), this.server.getServletPath());
+			if (this.multipartConfig != null) {
+				registration.setMultipartConfig(this.multipartConfig);
+			}
+			return registration;
 		}
 
 	}

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

@@ -16,15 +16,21 @@
 
 package org.springframework.boot.autoconfigure.web;
 
+import javax.servlet.MultipartConfigElement;
+
 import org.junit.Test;
+import org.springframework.boot.context.embedded.MultiPartConfigFactory;
 import org.springframework.boot.context.embedded.ServletRegistrationBean;
 import org.springframework.boot.test.EnvironmentTestUtils;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 import org.springframework.mock.web.MockServletContext;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 import org.springframework.web.servlet.DispatcherServlet;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 
 /**
  * Tests for {@link DispatcherServletAutoConfiguration}.
@@ -60,6 +66,33 @@ public class DispatcherServletAutoConfigurationTests {
 		ServletRegistrationBean registration = this.context
 				.getBean(ServletRegistrationBean.class);
 		assertEquals("[/spring]", registration.getUrlMappings().toString());
+		assertNull(registration.getMultipartConfig());
+	}
+
+	@Test
+	public void multipartConfig() throws Exception {
+		this.context = new AnnotationConfigWebApplicationContext();
+		this.context.setServletContext(new MockServletContext());
+		this.context.register(MultipartConfiguration.class,
+				ServerPropertiesAutoConfiguration.class,
+				DispatcherServletAutoConfiguration.class);
+		this.context.refresh();
+		ServletRegistrationBean registration = this.context
+				.getBean(ServletRegistrationBean.class);
+		assertNotNull(registration.getMultipartConfig());
+	}
+
+	@Configuration
+	protected static class MultipartConfiguration {
+
+		@Bean
+		public MultipartConfigElement multipartConfig() {
+			MultiPartConfigFactory factory = new MultiPartConfigFactory();
+			factory.setMaxFileSize("128KB");
+			factory.setMaxRequestSize("128KB");
+			return factory.createMultipartConfig();
+		}
+
 	}
 
 }