Detect ConfigurableWebBindingInitializer bean and register with MVC

Previously, to use a custom ConfigurableWebBindingInitializer, it was
necessary to extend WebMvcConfigurationSupport and override
getConfigurableWebBindingInitializer. This had the unwanted
side-effect of switching off the auto-configuration of Spring MVC.

This commit updates the auto-configuration to look for a
ConfigurableWebBindingInitializer bean and register it with Spring
MVC.

Closes gh-2526

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

@@ -27,6 +27,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.ListableBeanFactory;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.AutoConfigureOrder;
@@ -56,6 +57,7 @@ import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.validation.DefaultMessageCodesResolver;
 import org.springframework.validation.MessageCodesResolver;
 import org.springframework.web.accept.ContentNegotiationManager;
+import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.context.request.RequestContextListener;
 import org.springframework.web.filter.HiddenHttpMethodFilter;
 import org.springframework.web.filter.HttpPutFormContentFilter;
@@ -334,6 +336,9 @@ public class WebMvcAutoConfiguration {
 		@Autowired(required = false)
 		private WebMvcProperties mvcProperties;
 
+		@Autowired
+		private ListableBeanFactory beanFactory;
+
 		@Bean
 		@Override
 		public RequestMappingHandlerAdapter requestMappingHandlerAdapter() {
@@ -351,6 +356,16 @@ public class WebMvcAutoConfiguration {
 			return super.requestMappingHandlerMapping();
 		}
 
+		@Override
+		protected ConfigurableWebBindingInitializer getConfigurableWebBindingInitializer() {
+			try {
+				return this.beanFactory.getBean(ConfigurableWebBindingInitializer.class);
+			}
+			catch (NoSuchBeanDefinitionException ex) {
+				return super.getConfigurableWebBindingInitializer();
+			}
+		}
+
 	}
 
 }

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

@@ -37,6 +37,7 @@ import org.junit.rules.ExpectedException;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter;
+import org.springframework.boot.autoconfigure.web.WebMvcAutoConfigurationTests.CustomConfigurableWebBindingInitializer.CustomWebBindingInitializer;
 import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizerBeanPostProcessor;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerFactory;
@@ -52,6 +53,7 @@ import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
+import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.filter.HttpPutFormContentFilter;
 import org.springframework.web.servlet.HandlerAdapter;
 import org.springframework.web.servlet.HandlerMapping;
@@ -459,6 +461,14 @@ public class WebMvcAutoConfigurationTests {
 				is(equalTo(1)));
 	}
 
+	@Test
+	public void customConfigurableWebBindingInitializer() {
+		load(CustomConfigurableWebBindingInitializer.class);
+		assertThat(this.context.getBean(RequestMappingHandlerAdapter.class)
+				.getWebBindingInitializer(),
+				is(instanceOf(CustomWebBindingInitializer.class)));
+	}
+
 	@SuppressWarnings("unchecked")
 	private void load(Class<?> config, String... environment) {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext();
@@ -580,4 +590,19 @@ public class WebMvcAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	static class CustomConfigurableWebBindingInitializer {
+
+		@Bean
+		public ConfigurableWebBindingInitializer customConfigurableWebBindingInitializer() {
+			return new CustomWebBindingInitializer();
+
+		}
+
+		static class CustomWebBindingInitializer extends
+				ConfigurableWebBindingInitializer {
+
+		}
+	}
+
 }

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -1216,6 +1216,7 @@ The auto-configuration adds the following features on top of Spring's defaults:
 * Automatic registration of `MessageCodesResolver` (see below).
 * Static `index.html` support.
 * Custom `Favicon` support.
+* Automatic use of a `ConfigurableWebBindingInitializer` bean (see below).
 
 If you want to take complete control of Spring MVC, you can add your own `@Configuration`
 annotated with `@EnableWebMvc`. If you want to keep Spring Boot MVC features, and
@@ -1345,6 +1346,13 @@ https://spring.io/blog/2014/07/24/spring-framework-4-1-handling-static-web-resou
 and in Spring Framework's {spring-reference}/#mvc-config-static-resources[reference documentation].
 ====
 
+[[boot-features-spring-mvc-web-binding-initializer]]
+==== ConfigurableWebBindingInitializer
+
+Spring MVC uses a `WebBindingInitializer` to initialize a `WebDataBinder` for a particular
+request. If you create your own `ConfigurableWebBindingInitializer` `@Bean`, Spring Boot
+will automatically configure Spring MVC to use it.
+
 
 
 [[boot-features-spring-mvc-template-engines]]