Replace WebMvcConfigurerAdapter with default methods

Issue: SPR-15465

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/EnableWebMvc.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -38,14 +38,13 @@ import org.springframework.context.annotation.Import;
  * </pre>
  *
  * <p>To customize the imported configuration, implement the interface
- * {@link WebMvcConfigurer} or more likely extend the empty method base class
- * {@link WebMvcConfigurerAdapter} and override individual methods, e.g.:
+ * {@link WebMvcConfigurer} and override individual methods, e.g.:
  *
  * <pre class="code">
  * &#064;Configuration
  * &#064;EnableWebMvc
  * &#064;ComponentScan(basePackageClasses = MyConfiguration.class)
- * public class MyConfiguration extends WebMvcConfigurerAdapter {
+ * public class MyConfiguration implements WebMvcConfigurer {
  *
  * 	   &#064;Override
  * 	   public void addFormatters(FormatterRegistry formatterRegistry) {
@@ -93,7 +92,6 @@ import org.springframework.context.annotation.Import;
  * @author Rossen Stoyanchev
  * @since 3.1
  * @see org.springframework.web.servlet.config.annotation.WebMvcConfigurer
- * @see org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter
  * @see org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport
  * @see org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration
  */

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupport.java

@@ -168,7 +168,6 @@ import org.springframework.web.util.UrlPathHelper;
  * @since 3.1
  * @see EnableWebMvc
  * @see WebMvcConfigurer
- * @see WebMvcConfigurerAdapter
  */
 public class WebMvcConfigurationSupport implements ApplicationContextAware, ServletContextAware {
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -36,8 +36,7 @@ import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandl
  *
  * <p>{@code @EnableWebMvc}-annotated configuration classes may implement
  * this interface to be called back and given a chance to customize the
- * default configuration. Consider extending {@link WebMvcConfigurerAdapter},
- * which provides a stub implementation of all interface methods.
+ * default configuration.
  *
  * @author Rossen Stoyanchev
  * @author Keith Donald
@@ -57,17 +56,20 @@ public interface WebMvcConfigurer {
 	 * </ul>
 	 * @since 4.0.3
 	 */
-	void configurePathMatch(PathMatchConfigurer configurer);
+	default void configurePathMatch(PathMatchConfigurer configurer) {
+	}
 
 	/**
 	 * Configure content negotiation options.
 	 */
-	void configureContentNegotiation(ContentNegotiationConfigurer configurer);
+	default void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
+	}
 
 	/**
 	 * Configure asynchronous request handling options.
 	 */
-	void configureAsyncSupport(AsyncSupportConfigurer configurer);
+	default void configureAsyncSupport(AsyncSupportConfigurer configurer) {
+	}
 
 	/**
 	 * Configure a handler to delegate unhandled requests by forwarding to the
@@ -75,13 +77,15 @@ public interface WebMvcConfigurer {
 	 * the {@link DispatcherServlet} is mapped to "/" thus overriding the
 	 * Servlet container's default handling of static resources.
 	 */
-	void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer);
+	default void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
+	}
 
 	/**
 	 * Add {@link Converter}s and {@link Formatter}s in addition to the ones
 	 * registered by default.
 	 */
-	void addFormatters(FormatterRegistry registry);
+	default void addFormatters(FormatterRegistry registry) {
+	}
 
 	/**
 	 * Add Spring MVC lifecycle interceptors for pre- and post-processing of
@@ -95,20 +99,23 @@ public interface WebMvcConfigurer {
 	 * {@link org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport
 	 * WebMvcConfigurationSupport} and then override {@code resourceHandlerMapping}.
 	 */
-	void addInterceptors(InterceptorRegistry registry);
+	default void addInterceptors(InterceptorRegistry registry) {
+	}
 
 	/**
 	 * Add handlers to serve static resources such as images, js, and, css
 	 * files from specific locations under web application root, the classpath,
 	 * and others.
 	 */
-	void addResourceHandlers(ResourceHandlerRegistry registry);
+	default void addResourceHandlers(ResourceHandlerRegistry registry) {
+	}
 
 	/**
 	 * Configure cross origin requests processing.
 	 * @since 4.2
 	 */
-	void addCorsMappings(CorsRegistry registry);
+	default void addCorsMappings(CorsRegistry registry) {
+	}
 
 	/**
 	 * Configure simple automated controllers pre-configured with the response
@@ -117,7 +124,8 @@ public interface WebMvcConfigurer {
 	 * home page, perform simple site URL redirects, return a 404 status with
 	 * HTML content, a 204 with no content, and more.
 	 */
-	void addViewControllers(ViewControllerRegistry registry);
+	default void addViewControllers(ViewControllerRegistry registry) {
+	}
 
 	/**
 	 * Configure view resolvers to translate String-based view names returned from
@@ -125,25 +133,28 @@ public interface WebMvcConfigurer {
 	 * implementations to perform rendering with.
 	 * @since 4.1
 	 */
-	void configureViewResolvers(ViewResolverRegistry registry);
+	default void configureViewResolvers(ViewResolverRegistry registry) {
+	}
 
 	/**
 	 * Add resolvers to support custom controller method argument types.
 	 * <p>This does not override the built-in support for resolving handler
 	 * method arguments. To customize the built-in support for argument
 	 * resolution, configure {@link RequestMappingHandlerAdapter} directly.
-	 * @param argumentResolvers initially an empty list
+	 * @param resolvers initially an empty list
 	 */
-	void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers);
+	default void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
+	}
 
 	/**
 	 * Add handlers to support custom controller method return value types.
 	 * <p>Using this option does not override the built-in support for handling
 	 * return values. To customize the built-in support for handling return
 	 * values, configure RequestMappingHandlerAdapter directly.
-	 * @param returnValueHandlers initially an empty list
+	 * @param handlers initially an empty list
 	 */
-	void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers);
+	default void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> handlers) {
+	}
 
 	/**
 	 * Configure the {@link HttpMessageConverter}s to use for reading or writing
@@ -155,7 +166,8 @@ public interface WebMvcConfigurer {
 	 * {@link #extendMessageConverters(java.util.List)} instead.
 	 * @param converters initially an empty list of converters
 	 */
-	void configureMessageConverters(List<HttpMessageConverter<?>> converters);
+	default void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
+	}
 
 	/**
 	 * A hook for extending or modifying the list of converters after it has been
@@ -164,7 +176,8 @@ public interface WebMvcConfigurer {
 	 * @param converters the list of configured converters to extend.
 	 * @since 4.1.3
 	 */
-	void extendMessageConverters(List<HttpMessageConverter<?>> converters);
+	default void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
+	}
 
 	/**
 	 * Configure exception resolvers.
@@ -177,21 +190,23 @@ public interface WebMvcConfigurer {
 	 * <p>Alternatively you can use
 	 * {@link #extendHandlerExceptionResolvers(List)} which allows you to extend
 	 * or modify the list of exception resolvers configured by default.
-	 * @param exceptionResolvers initially an empty list
+	 * @param resolvers initially an empty list
 	 * @see #extendHandlerExceptionResolvers(List)
 	 * @see WebMvcConfigurationSupport#addDefaultHandlerExceptionResolvers(List)
 	 */
-	void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers);
+	default void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
+	}
 
 	/**
 	 * Extending or modify the list of exception resolvers configured by default.
 	 * This can be useful for inserting a custom exception resolver without
 	 * interfering with default ones.
-	 * @param exceptionResolvers the list of configured resolvers to extend
+	 * @param resolvers the list of configured resolvers to extend
 	 * @since 4.3
 	 * @see WebMvcConfigurationSupport#addDefaultHandlerExceptionResolvers(List)
 	 */
-	void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers);
+	default void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
+	}
 
 	/**
 	 * Provide a custom {@link Validator} instead of the one created by default.
@@ -199,13 +214,17 @@ public interface WebMvcConfigurer {
 	 * {@link org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean}.
 	 * Leave the return value as {@code null} to keep the default.
 	 */
-	Validator getValidator();
+	default Validator getValidator() {
+		return null;
+	}
 
 	/**
 	 * Provide a custom {@link MessageCodesResolver} for building message codes
 	 * from data binding and validation error codes. Leave the return value as
 	 * {@code null} to keep the default.
 	 */
-	MessageCodesResolver getMessageCodesResolver();
+	default MessageCodesResolver getMessageCodesResolver() {
+		return null;
+	}
 
 }

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurerAdapter.java

@@ -32,7 +32,11 @@ import org.springframework.web.servlet.HandlerExceptionResolver;
  *
  * @author Rossen Stoyanchev
  * @since 3.1
+ * @deprecated as of 5.0 {@link WebMvcConfigurer} has default methods (made
+ * possible by a Java 8 baseline) and can be implemented directly without the
+ * need for this adapter
  */
+@Deprecated
 public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/AppCacheManifestTransformer.java

@@ -55,7 +55,7 @@ import org.springframework.util.StringUtils;
  * <p>In order to serve manifest files with the proper {@code "text/manifest"} content type,
  * it is required to configure it with
  * {@code contentNegotiationConfigurer.mediaType("appcache", MediaType.valueOf("text/manifest")}
- * in a {@code WebMvcConfigurerAdapter}.
+ * in a {@code WebMvcConfigurer}.
  *
  * @author Brian Clozel
  * @since 4.1

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/DelegatingWebMvcConfigurationTests.java

@@ -46,8 +46,13 @@ import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandl
 import org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver;
 import org.springframework.web.util.UrlPathHelper;
 
-import static org.junit.Assert.*;
-import static org.mockito.BDDMockito.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.mock;
+import static org.mockito.BDDMockito.verify;
 
 /**
  * A test fixture for {@link DelegatingWebMvcConfiguration} tests.
@@ -118,7 +123,7 @@ public class DelegatingWebMvcConfigurationTests {
 		final HttpMessageConverter customConverter = mock(HttpMessageConverter.class);
 		final StringHttpMessageConverter stringConverter = new StringHttpMessageConverter();
 		List<WebMvcConfigurer> configurers = new ArrayList<>();
-		configurers.add(new WebMvcConfigurerAdapter() {
+		configurers.add(new WebMvcConfigurer() {
 			@Override
 			public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
 				converters.add(stringConverter);
@@ -176,7 +181,7 @@ public class DelegatingWebMvcConfigurationTests {
 	@Test
 	public void configureExceptionResolvers() throws Exception {
 		List<WebMvcConfigurer> configurers = new ArrayList<>();
-		configurers.add(new WebMvcConfigurerAdapter() {
+		configurers.add(new WebMvcConfigurer() {
 			@Override
 			public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
 				exceptionResolvers.add(new DefaultHandlerExceptionResolver());
@@ -195,7 +200,7 @@ public class DelegatingWebMvcConfigurationTests {
 		final UrlPathHelper pathHelper = mock(UrlPathHelper.class);
 
 		List<WebMvcConfigurer> configurers = new ArrayList<>();
-		configurers.add(new WebMvcConfigurerAdapter() {
+		configurers.add(new WebMvcConfigurer() {
 			@Override
 			public void configurePathMatch(PathMatchConfigurer configurer) {
 				configurer.setUseRegisteredSuffixPatternMatch(true)

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/ViewResolutionIntegrationTests.java

@@ -40,7 +40,7 @@ import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;
 import org.springframework.web.servlet.view.groovy.GroovyMarkupConfigurer;
 import org.springframework.web.servlet.view.tiles3.TilesConfigurer;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 
 /**
  * Integration tests for view resolution with {@code @EnableWebMvc}.
@@ -128,7 +128,7 @@ public class ViewResolutionIntegrationTests {
 	}
 
 	@EnableWebMvc
-	static abstract class AbstractWebConfig extends WebMvcConfigurerAdapter {
+	static abstract class AbstractWebConfig implements WebMvcConfigurer {
 
 		@Bean
 		public SampleController sampleController() {

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupportTests.java

@@ -18,7 +18,6 @@ package org.springframework.web.servlet.config.annotation;
 
 import java.util.List;
 import java.util.Locale;
-
 import javax.servlet.http.HttpServletRequest;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -363,7 +362,7 @@ public class WebMvcConfigurationSupportTests {
 
 	@EnableWebMvc
 	@Configuration
-	static class CustomViewResolverOrderConfig extends WebMvcConfigurerAdapter {
+	static class CustomViewResolverOrderConfig implements WebMvcConfigurer {
 
 		@Override
 		public void configureViewResolvers(ViewResolverRegistry registry) {
@@ -374,7 +373,7 @@ public class WebMvcConfigurationSupportTests {
 
 	@EnableWebMvc
 	@Configuration
-	static class CustomArgumentResolverConfig extends WebMvcConfigurerAdapter {
+	static class CustomArgumentResolverConfig implements WebMvcConfigurer {
 
 		@Override
 		public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilderTests.java

@@ -50,13 +50,21 @@ import org.springframework.web.context.request.ServletRequestAttributes;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
-import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 
-import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
-import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.*;
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.Matchers.endsWith;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.startsWith;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.fromController;
+import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.fromMethodCall;
+import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.fromMethodName;
+import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.on;
 
 /**
  * Unit tests for {@link org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder}.
@@ -500,7 +508,7 @@ public class MvcUriComponentsBuilderTests {
 
 
 	@EnableWebMvc
-	static class WebConfig extends WebMvcConfigurerAdapter {
+	static class WebConfig implements WebMvcConfigurer {
 
 		@Bean
 		public PersonsAddressesController controller() {

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestPartIntegrationTests.java

@@ -65,10 +65,10 @@ import org.springframework.web.multipart.commons.CommonsMultipartResolver;
 import org.springframework.web.multipart.support.StandardServletMultipartResolver;
 import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
-import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
-import static org.junit.Assert.*;
-import static org.springframework.web.bind.annotation.RequestMethod.*;
+import static org.junit.Assert.assertEquals;
+import static org.springframework.web.bind.annotation.RequestMethod.POST;
 
 /**
  * Test access to parts of a multipart request with {@link RequestPart}.
@@ -198,7 +198,7 @@ public class RequestPartIntegrationTests {
 
 	@Configuration
 	@EnableWebMvc
-	static class RequestPartTestConfig extends WebMvcConfigurerAdapter {
+	static class RequestPartTestConfig implements WebMvcConfigurer {
 
 		@Bean
 		public RequestPartTestController controller() {