Add MessageCodesResolver hook to WebMvcConfigurer

This change makes it possible to provide a custom MessageCodesResolver
through the MVC Java config whether using @EnableWebMvc and extending
WebMVcConfigurerAdapter or sub-classing directly from
WebMvcConfigurationSupport.

Issue: SPR-9223

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -22,20 +22,20 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 
 /**
- * Extends {@link WebMvcConfigurationSupport} with the ability to detect beans
- * of type {@link WebMvcConfigurer} and give them a chance to customize the 
- * provided configuration by delegating to them at the appropriate times.
- * 
+ * A sub-class of {@code WebMvcConfigurationSupport} that detects and delegates
+ * to all beans of type {@link WebMvcConfigurer} allowing them to customize the
+ * configuration provided by {@code WebMvcConfigurationSupport}. This is the
+ * class actually imported by {@link EnableWebMvc @EnableWebMvc}.
+ *
  * @author Rossen Stoyanchev
  * @since 3.1
- * 
- * @see EnableWebMvc
  */
 @Configuration
 public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
@@ -52,52 +52,57 @@ public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
 
 	@Override
 	protected void addInterceptors(InterceptorRegistry registry) {
-		configurers.addInterceptors(registry);
+		this.configurers.addInterceptors(registry);
 	}
 
 	@Override
 	protected void addViewControllers(ViewControllerRegistry registry) {
-		configurers.addViewControllers(registry);
+		this.configurers.addViewControllers(registry);
 	}
 
 	@Override
 	protected void addResourceHandlers(ResourceHandlerRegistry registry) {
-		configurers.addResourceHandlers(registry);
+		this.configurers.addResourceHandlers(registry);
 	}
 
 	@Override
 	protected void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
-		configurers.configureDefaultServletHandling(configurer);
+		this.configurers.configureDefaultServletHandling(configurer);
 	}
-	
+
 	@Override
 	protected void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
-		configurers.addArgumentResolvers(argumentResolvers);
+		this.configurers.addArgumentResolvers(argumentResolvers);
 	}
 
 	@Override
 	protected void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
-		configurers.addReturnValueHandlers(returnValueHandlers);
+		this.configurers.addReturnValueHandlers(returnValueHandlers);
 	}
 
 	@Override
 	protected void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
-		configurers.configureMessageConverters(converters);
+		this.configurers.configureMessageConverters(converters);
 	}
 
 	@Override
 	protected void addFormatters(FormatterRegistry registry) {
-		configurers.addFormatters(registry);
+		this.configurers.addFormatters(registry);
 	}
 
 	@Override
 	protected Validator getValidator() {
-		return configurers.getValidator();
+		return this.configurers.getValidator();
+	}
+
+	@Override
+	protected MessageCodesResolver getMessageCodesResolver() {
+		return this.configurers.getMessageCodesResolver();
 	}
 
 	@Override
 	protected void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		configurers.configureHandlerExceptionResolvers(exceptionResolvers);
+		this.configurers.configureHandlerExceptionResolvers(exceptionResolvers);
 	}
 
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -48,6 +48,7 @@ import org.springframework.http.converter.xml.SourceHttpMessageConverter;
 import org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter;
 import org.springframework.util.ClassUtils;
 import org.springframework.validation.Errors;
+import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.HttpRequestHandler;
@@ -280,6 +281,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		ConfigurableWebBindingInitializer webBindingInitializer = new ConfigurableWebBindingInitializer();
 		webBindingInitializer.setConversionService(mvcConversionService());
 		webBindingInitializer.setValidator(mvcValidator());
+		webBindingInitializer.setMessageCodesResolver(getMessageCodesResolver());
 
 		List<HandlerMethodArgumentResolver> argumentResolvers = new ArrayList<HandlerMethodArgumentResolver>();
 		addArgumentResolvers(argumentResolvers);
@@ -295,6 +297,69 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		return adapter;
 	}
 
+	/**
+	 * Returns a {@link FormattingConversionService} for use with annotated
+	 * controller methods and the {@code spring:eval} JSP tag.
+	 * Also see {@link #addFormatters} as an alternative to overriding this method.
+	 */
+	@Bean
+	public FormattingConversionService mvcConversionService() {
+		FormattingConversionService conversionService = new DefaultFormattingConversionService();
+		addFormatters(conversionService);
+		return conversionService;
+	}
+
+	/**
+	 * Returns a global {@link Validator} instance for example for validating
+	 * {@code @ModelAttribute} and {@code @RequestBody} method arguments.
+	 * Delegates to {@link #getValidator()} first and if that returns {@code null}
+	 * checks the classpath for the presence of a JSR-303 implementations
+	 * before creating a {@code LocalValidatorFactoryBean}.If a JSR-303
+	 * implementation is not available, a no-op {@link Validator} is returned.
+	 */
+	@Bean
+	public Validator mvcValidator() {
+		Validator validator = getValidator();
+		if (validator == null) {
+			if (ClassUtils.isPresent("javax.validation.Validator", getClass().getClassLoader())) {
+				Class<?> clazz;
+				try {
+					String className = "org.springframework.validation.beanvalidation.LocalValidatorFactoryBean";
+					clazz = ClassUtils.forName(className, WebMvcConfigurationSupport.class.getClassLoader());
+				} catch (ClassNotFoundException e) {
+					throw new BeanInitializationException("Could not find default validator", e);
+				} catch (LinkageError e) {
+					throw new BeanInitializationException("Could not find default validator", e);
+				}
+				validator = (Validator) BeanUtils.instantiate(clazz);
+			}
+			else {
+				validator = new Validator() {
+					public boolean supports(Class<?> clazz) {
+						return false;
+					}
+					public void validate(Object target, Errors errors) {
+					}
+				};
+			}
+		}
+		return validator;
+	}
+
+	/**
+	 * Override this method to provide a custom {@link Validator}.
+	 */
+	protected Validator getValidator() {
+		return null;
+	}
+
+	/**
+	 * Override this method to provide a custom {@link MessageCodesResolver}.
+	 */
+	protected MessageCodesResolver getMessageCodesResolver() {
+		return null;
+	}
+
 	/**
 	 * Add custom {@link HandlerMethodArgumentResolver}s to use in addition to
 	 * the ones registered by default.
@@ -387,68 +452,12 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		}
 	}
 
-	/**
-	 * Returns a {@link FormattingConversionService} for use with annotated
-	 * controller methods and the {@code spring:eval} JSP tag.
-	 * Also see {@link #addFormatters} as an alternative to overriding this method.
-	 */
-	@Bean
-	public FormattingConversionService mvcConversionService() {
-		FormattingConversionService conversionService = new DefaultFormattingConversionService();
-		addFormatters(conversionService);
-		return conversionService;
-	}
-
 	/**
 	 * Override this method to add custom {@link Converter}s and {@link Formatter}s.
 	 */
 	protected void addFormatters(FormatterRegistry registry) {
 	}
 
-	/**
-	 * Returns a global {@link Validator} instance for example for validating
-	 * {@code @ModelAttribute} and {@code @RequestBody} method arguments.
-	 * Delegates to {@link #getValidator()} first and if that returns {@code null}
-	 * checks the classpath for the presence of a JSR-303 implementations
-	 * before creating a {@code LocalValidatorFactoryBean}.If a JSR-303
-	 * implementation is not available, a no-op {@link Validator} is returned.
-	 */
-	@Bean
-	public Validator mvcValidator() {
-		Validator validator = getValidator();
-		if (validator == null) {
-			if (ClassUtils.isPresent("javax.validation.Validator", getClass().getClassLoader())) {
-				Class<?> clazz;
-				try {
-					String className = "org.springframework.validation.beanvalidation.LocalValidatorFactoryBean";
-					clazz = ClassUtils.forName(className, WebMvcConfigurationSupport.class.getClassLoader());
-				} catch (ClassNotFoundException e) {
-					throw new BeanInitializationException("Could not find default validator", e);
-				} catch (LinkageError e) {
-					throw new BeanInitializationException("Could not find default validator", e);
-				}
-				validator = (Validator) BeanUtils.instantiate(clazz);
-			}
-			else {
-				validator = new Validator() {
-					public boolean supports(Class<?> clazz) {
-						return false;
-					}
-					public void validate(Object target, Errors errors) {
-					}
-				};
-			}
-		}
-		return validator;
-	}
-
-	/**
-	 * Override this method to provide a custom {@link Validator}.
-	 */
-	protected Validator getValidator() {
-		return null;
-	}
-
 	/**
 	 * Returns a {@link HttpRequestHandlerAdapter} for processing requests
 	 * with {@link HttpRequestHandler}s.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -22,6 +22,7 @@ import org.springframework.core.convert.converter.Converter;
 import org.springframework.format.Formatter;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
@@ -30,10 +31,10 @@ import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
 
 /**
- * Defines callback methods to customize the Java-based configuration for 
- * Spring MVC enabled via {@code @EnableWebMvc}. 
- * 
- * <p>{@code @EnableWebMvc}-annotated configuration classes may implement 
+ * Defines callback methods to customize the Java-based configuration for
+ * Spring MVC enabled via {@code @EnableWebMvc}.
+ *
+ * <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.
@@ -46,7 +47,7 @@ import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandl
 public interface WebMvcConfigurer {
 
 	/**
-	 * Add {@link Converter}s and {@link Formatter}s in addition to the ones 
+	 * Add {@link Converter}s and {@link Formatter}s in addition to the ones
 	 * registered by default.
 	 */
 	void addFormatters(FormatterRegistry registry);
@@ -69,25 +70,25 @@ public interface WebMvcConfigurer {
 	Validator getValidator();
 
 	/**
-	 * 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 
+	 * 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
 	 */
 	void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers);
 
 	/**
-	 * Add handlers to support custom controller method return value types. 
+	 * 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 
+	 * return values. To customize the built-in support for handling return
 	 * values, configure RequestMappingHandlerAdapter directly.
 	 * @param returnValueHandlers initially an empty list
 	 */
 	void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers);
 
 	/**
-	 * Configure the {@link HandlerExceptionResolver}s to handle unresolved 
+	 * Configure the {@link HandlerExceptionResolver}s to handle unresolved
 	 * controller exceptions. If no resolvers are added to the list, default
 	 * exception resolvers are added instead.
 	 * @param exceptionResolvers initially an empty list
@@ -95,29 +96,36 @@ public interface WebMvcConfigurer {
 	void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers);
 
 	/**
-	 * Add Spring MVC lifecycle interceptors for pre- and post-processing of 
-	 * controller method invocations. Interceptors can be registered to apply 
+	 * Add Spring MVC lifecycle interceptors for pre- and post-processing of
+	 * controller method invocations. Interceptors can be registered to apply
 	 * to all requests or be limited to a subset of URL patterns.
 	 */
 	void addInterceptors(InterceptorRegistry registry);
 
 	/**
-	 * Add view controllers to create a direct mapping between a URL path and 
-	 * view name without the need for a controller in between. 
+	 * 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();
+
+	/**
+	 * Add view controllers to create a direct mapping between a URL path and
+	 * view name without the need for a controller in between.
 	 */
 	void addViewControllers(ViewControllerRegistry registry);
 
 	/**
-	 * Add handlers to serve static resources such as images, js, and, css 
+	 * 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);
 
 	/**
-	 * Configure a handler to delegate unhandled requests by forwarding to the 
+	 * Configure a handler to delegate unhandled requests by forwarding to the
 	 * Servlet container's "default" servlet. A common use case for this is when
-	 * the {@link DispatcherServlet} is mapped to "/" thus overriding the 
+	 * the {@link DispatcherServlet} is mapped to "/" thus overriding the
 	 * Servlet container's default handling of static resources.
 	 */
 	void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -20,13 +20,15 @@ import java.util.List;
 
 import org.springframework.format.FormatterRegistry;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 
 /**
- * An convenient base class with empty method implementations of {@link WebMvcConfigurer}.
+ * An implementation of {@link WebMvcConfigurer} with empty methods allowing
+ * sub-classes to override only the methods they're interested in.
  *
  * @author Rossen Stoyanchev
  * @since 3.1
@@ -76,6 +78,14 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
 	}
 
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation is empty.
+	 */
+	public MessageCodesResolver getMessageCodesResolver() {
+		return null;
+	}
+
 	/**
 	 * {@inheritDoc}
 	 * <p>This implementation is empty.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -17,12 +17,11 @@
 package org.springframework.web.servlet.config.annotation;
 
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 
 import org.springframework.format.FormatterRegistry;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
@@ -45,77 +44,92 @@ class WebMvcConfigurerComposite implements WebMvcConfigurer {
 	}
 
 	public void addFormatters(FormatterRegistry registry) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.addFormatters(registry);
 		}
 	}
 
 	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.configureMessageConverters(converters);
 		}
 	}
 
 	public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.addArgumentResolvers(argumentResolvers);
 		}
 	}
 
 	public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.addReturnValueHandlers(returnValueHandlers);
 		}
 	}
 
 	public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.configureHandlerExceptionResolvers(exceptionResolvers);
 		}
 	}
 
 	public void addInterceptors(InterceptorRegistry registry) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.addInterceptors(registry);
 		}
 	}
 
 	public void addViewControllers(ViewControllerRegistry registry) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.addViewControllers(registry);
 		}
 	}
 
 	public void addResourceHandlers(ResourceHandlerRegistry registry) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.addResourceHandlers(registry);
 		}
 	}
 
 	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
-		for (WebMvcConfigurer delegate : delegates) {
+		for (WebMvcConfigurer delegate : this.delegates) {
 			delegate.configureDefaultServletHandling(configurer);
 		}
 	}
 
 	public Validator getValidator() {
-		Map<WebMvcConfigurer, Validator> validators = new HashMap<WebMvcConfigurer, Validator>();
-		for (WebMvcConfigurer delegate : delegates) {
-			Validator validator = delegate.getValidator();
+		List<Validator> candidates = new ArrayList<Validator>();
+		for (WebMvcConfigurer configurer : this.delegates) {
+			Validator validator = configurer.getValidator();
 			if (validator != null) {
-				validators.put(delegate, validator);
+				candidates.add(validator);
 			}
 		}
-		if (validators.size() == 0) {
-			return null;
+		return selectSingleInstance(candidates, Validator.class);
+	}
+
+	private <T> T selectSingleInstance(List<T> instances, Class<T> instanceType) {
+		if (instances.size() > 1) {
+			throw new IllegalStateException(
+					"Only one [" + instanceType + "] was expected but multiple instances were provided: " + instances);
 		}
-		else if (validators.size() == 1) {
-			return validators.values().iterator().next();
+		else if (instances.size() == 1) {
+			return instances.get(0);
 		}
 		else {
-			throw new IllegalStateException(
-					"Multiple custom validators provided from [" + validators.keySet() + "]");
+			return null;
 		}
 	}
 
+	public MessageCodesResolver getMessageCodesResolver() {
+		List<MessageCodesResolver> candidates = new ArrayList<MessageCodesResolver>();
+		for (WebMvcConfigurer configurer : this.delegates) {
+			MessageCodesResolver messageCodesResolver = configurer.getMessageCodesResolver();
+			if (messageCodesResolver != null) {
+				candidates.add(messageCodesResolver);
+			}
+		}
+		return selectSingleInstance(candidates, MessageCodesResolver.class);
+	}
+
 }