Refactor AcceptHeaderLocaleResolver to implement LocaleContextResolver

spring-test/src/main/java/org/springframework/test/web/servlet/client/MockMvcWebTestClient.java

@@ -45,7 +45,7 @@
 import org.springframework.web.servlet.FlashMapManager;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.HandlerInterceptor;
-import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.LocaleContextResolver;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
@@ -335,9 +335,9 @@ ControllerSpec mappedInterceptors(
 		/**
 		 * Provide the LocaleResolver to use.
 		 * <p>This is delegated to
-		 * {@link StandaloneMockMvcBuilder#setLocaleResolver(LocaleResolver)}.
+		 * {@link StandaloneMockMvcBuilder#setLocaleResolver(LocaleContextResolver)}.
 		 */
-		ControllerSpec localeResolver(LocaleResolver localeResolver);
+		ControllerSpec localeResolver(LocaleContextResolver localeResolver);
 
 		/**
 		 * Provide a custom FlashMapManager.

spring-test/src/main/java/org/springframework/test/web/servlet/client/StandaloneMockMvcSpec.java

@@ -31,7 +31,7 @@
 import org.springframework.web.servlet.FlashMapManager;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.HandlerInterceptor;
-import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.LocaleContextResolver;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
@@ -135,7 +135,7 @@ public StandaloneMockMvcSpec singleView(View view) {
 	}
 
 	@Override
-	public StandaloneMockMvcSpec localeResolver(LocaleResolver localeResolver) {
+	public StandaloneMockMvcSpec localeResolver(LocaleContextResolver localeResolver) {
 		this.mockMvcBuilder.setLocaleResolver(localeResolver);
 		return this;
 	}

spring-test/src/main/java/org/springframework/test/web/servlet/setup/StandaloneMockMvcBuilder.java

@@ -51,7 +51,7 @@
 import org.springframework.web.servlet.FlashMapManager;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.HandlerInterceptor;
-import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.LocaleContextResolver;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer;
@@ -121,7 +121,7 @@ public class StandaloneMockMvcBuilder extends AbstractMockMvcBuilder<StandaloneM
 	@Nullable
 	private List<ViewResolver> viewResolvers;
 
-	private LocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
+	private LocaleContextResolver localeResolver = new AcceptHeaderLocaleResolver();
 
 	@Nullable
 	private FlashMapManager flashMapManager;
@@ -297,7 +297,7 @@ public StandaloneMockMvcBuilder setSingleView(View view) {
 	 * Provide a LocaleResolver instance.
 	 * If not provided, the default one used is {@link AcceptHeaderLocaleResolver}.
 	 */
-	public StandaloneMockMvcBuilder setLocaleResolver(LocaleResolver localeResolver) {
+	public StandaloneMockMvcBuilder setLocaleResolver(LocaleContextResolver localeResolver) {
 		this.localeResolver = localeResolver;
 		return this;
 	}

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

@@ -120,7 +120,7 @@
  * implementation for Servlet 3 is included. The MultipartResolver bean name is
  * "multipartResolver"; default is none.
  *
- * <li>Its locale resolution strategy is determined by a {@link LocaleResolver}.
+ * <li>Its locale resolution strategy is determined by a {@link LocaleContextResolver}.
  * Out-of-the-box implementations work via HTTP accept header, cookie, or session.
  * The LocaleResolver bean name is "localeResolver"; default is
  * {@link org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver}.
@@ -156,6 +156,7 @@
  * @author Chris Beams
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
+ * @author Vedran Pavic
  * @see org.springframework.web.HttpRequestHandler
  * @see org.springframework.web.servlet.mvc.Controller
  * @see org.springframework.web.context.ContextLoaderListener
@@ -313,9 +314,9 @@ public class DispatcherServlet extends FrameworkServlet {
 	@Nullable
 	private MultipartResolver multipartResolver;
 
-	/** LocaleResolver used by this servlet. */
+	/** LocaleContextResolver used by this servlet. */
 	@Nullable
-	private LocaleResolver localeResolver;
+	private LocaleContextResolver localeResolver;
 
 	/** ThemeResolver used by this servlet. */
 	@Nullable
@@ -543,7 +544,7 @@ else if (logger.isDebugEnabled()) {
 	 */
 	private void initLocaleResolver(ApplicationContext context) {
 		try {
-			this.localeResolver = context.getBean(LOCALE_RESOLVER_BEAN_NAME, LocaleResolver.class);
+			this.localeResolver = context.getBean(LOCALE_RESOLVER_BEAN_NAME, LocaleContextResolver.class);
 			if (logger.isTraceEnabled()) {
 				logger.trace("Detected " + this.localeResolver);
 			}
@@ -553,7 +554,7 @@ else if (logger.isDebugEnabled()) {
 		}
 		catch (NoSuchBeanDefinitionException ex) {
 			// We need to use the default.
-			this.localeResolver = getDefaultStrategy(context, LocaleResolver.class);
+			this.localeResolver = getDefaultStrategy(context, LocaleContextResolver.class);
 			if (logger.isTraceEnabled()) {
 				logger.trace("No LocaleResolver '" + LOCALE_RESOLVER_BEAN_NAME +
 						"': using default [" + this.localeResolver.getClass().getSimpleName() + "]");
@@ -1186,13 +1187,8 @@ private void processDispatchResult(HttpServletRequest request, HttpServletRespon
 	 */
 	@Override
 	protected LocaleContext buildLocaleContext(final HttpServletRequest request) {
-		LocaleResolver lr = this.localeResolver;
-		if (lr instanceof LocaleContextResolver) {
-			return ((LocaleContextResolver) lr).resolveLocaleContext(request);
-		}
-		else {
-			return () -> (lr != null ? lr.resolveLocale(request) : request.getLocale());
-		}
+		LocaleContextResolver lr = this.localeResolver;
+		return (lr != null ? lr.resolveLocaleContext(request) : request::getLocale);
 	}
 
 	/**
@@ -1379,8 +1375,13 @@ else if (logger.isDebugEnabled()) {
 	 */
 	protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception {
 		// Determine locale for request and apply it to the response.
-		Locale locale =
-				(this.localeResolver != null ? this.localeResolver.resolveLocale(request) : request.getLocale());
+		Locale locale = null;
+		if (this.localeResolver != null) {
+			locale = this.localeResolver.resolveLocaleContext(request).getLocale();
+		}
+		if (locale == null) {
+			locale = request.getLocale();
+		}
 		response.setLocale(locale);
 
 		View view;

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

@@ -42,6 +42,7 @@
  * @see org.springframework.web.servlet.support.RequestContext#getTimeZone
  * @see org.springframework.web.servlet.support.RequestContextUtils#getTimeZone
  */
+@SuppressWarnings("deprecation")
 public interface LocaleContextResolver extends LocaleResolver {
 
 	/**
@@ -58,7 +59,6 @@ public interface LocaleContextResolver extends LocaleResolver {
 	 * the returned context, which again can be accessed through downcasting.
 	 * @param request the request to resolve the locale context for
 	 * @return the current locale context (never {@code null}
-	 * @see #resolveLocale(HttpServletRequest)
 	 * @see org.springframework.web.servlet.support.RequestContextUtils#getLocale
 	 * @see org.springframework.web.servlet.support.RequestContextUtils#getTimeZone
 	 */
@@ -72,7 +72,6 @@ public interface LocaleContextResolver extends LocaleResolver {
 	 * @param localeContext the new locale context, or {@code null} to clear the locale
 	 * @throws UnsupportedOperationException if the LocaleResolver implementation
 	 * does not support dynamic changing of the locale or time zone
-	 * @see #setLocale(HttpServletRequest, HttpServletResponse, Locale)
 	 * @see org.springframework.context.i18n.SimpleLocaleContext
 	 * @see org.springframework.context.i18n.SimpleTimeZoneAwareLocaleContext
 	 */

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

@@ -50,7 +50,9 @@
  * @see org.springframework.context.i18n.LocaleContextHolder
  * @see org.springframework.web.servlet.support.RequestContext#getLocale
  * @see org.springframework.web.servlet.support.RequestContextUtils#getLocale
+ * @deprecated since 6.0 in favor of {@link LocaleContextResolver}
  */
+@Deprecated(since = "6.0")
 public interface LocaleResolver {
 
 	/**

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

@@ -80,7 +80,7 @@
 import org.springframework.web.servlet.HandlerAdapter;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.HandlerMapping;
-import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.LocaleContextResolver;
 import org.springframework.web.servlet.RequestToViewNameTranslator;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.function.support.HandlerFunctionAdapter;
@@ -1158,7 +1158,7 @@ public HandlerMappingIntrospector mvcHandlerMappingIntrospector() {
 	}
 
 	@Bean
-	public LocaleResolver localeResolver() {
+	public LocaleContextResolver localeResolver() {
 		return new AcceptHeaderLocaleResolver();
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/DispatcherServletWebRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -28,12 +28,12 @@
  * {@link ServletWebRequest} subclass that is aware of
  * {@link org.springframework.web.servlet.DispatcherServlet}'s
  * request context, such as the Locale determined by the configured
- * {@link org.springframework.web.servlet.LocaleResolver}.
+ * {@link org.springframework.web.servlet.LocaleContextResolver}.
  *
  * @author Juergen Hoeller
  * @since 2.0
  * @see #getLocale()
- * @see org.springframework.web.servlet.LocaleResolver
+ * @see org.springframework.web.servlet.LocaleContextResolver
  */
 public class DispatcherServletWebRequest extends ServletWebRequest {
 

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AbstractLocaleContextResolver.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.servlet.i18n;
 
+import java.util.Locale;
 import java.util.TimeZone;
 
 import org.springframework.lang.Nullable;
@@ -32,12 +33,32 @@
  * @see #setDefaultLocale
  * @see #setDefaultTimeZone
  */
-public abstract class AbstractLocaleContextResolver extends AbstractLocaleResolver implements LocaleContextResolver {
+public abstract class AbstractLocaleContextResolver implements LocaleContextResolver {
+
+	@Nullable
+	private Locale defaultLocale;
 
 	@Nullable
 	private TimeZone defaultTimeZone;
 
 
+	/**
+	 * Set a default {@link Locale} that this resolver will return if no other
+	 * locale is found.
+	 */
+	public void setDefaultLocale(@Nullable Locale defaultLocale) {
+		this.defaultLocale = defaultLocale;
+	}
+
+	/**
+	 * Get the default {@link Locale} that this resolver is supposed to fall back
+	 * to, if any.
+	 */
+	@Nullable
+	protected Locale getDefaultLocale() {
+		return this.defaultLocale;
+	}
+
 	/**
 	 * Set a default {@link TimeZone} that this resolver will return if no other
 	 * time zone is found.

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AbstractLocaleResolver.java

@@ -29,7 +29,9 @@
  * @author Juergen Hoeller
  * @since 1.2.9
  * @see #setDefaultLocale
+ * @deprecated since 6.0 in favor of {@link AbstractLocaleContextResolver}
  */
+@Deprecated(since = "6.0")
 public abstract class AbstractLocaleResolver implements LocaleResolver {
 
 	@Nullable

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AcceptHeaderLocaleResolver.java

@@ -24,24 +24,26 @@
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 
+import org.springframework.context.i18n.LocaleContext;
+import org.springframework.context.i18n.SimpleLocaleContext;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
-import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.LocaleContextResolver;
 
 /**
- * {@link LocaleResolver} implementation that simply uses the primary locale
+ * {@link LocaleContextResolver} implementation that simply uses the primary locale
  * specified in the {@code Accept-Language} header of the HTTP request (that is,
  * the locale sent by the client browser, normally that of the client's OS).
  *
- * <p>Note: Does not support {@link #setLocale} since the {@code Accept-Language}
+ * <p>Note: Does not support {@link #setLocaleContext} since the {@code Accept-Language}
  * header can only be changed by changing the client's locale settings.
  *
  * @author Juergen Hoeller
  * @author Rossen Stoyanchev
  * @since 27.02.2003
  * @see jakarta.servlet.http.HttpServletRequest#getLocale()
  */
-public class AcceptHeaderLocaleResolver extends AbstractLocaleResolver {
+public class AcceptHeaderLocaleResolver extends AbstractLocaleContextResolver {
 
 	private final List<Locale> supportedLocales = new ArrayList<>(4);
 
@@ -68,21 +70,21 @@ public List<Locale> getSupportedLocales() {
 
 
 	@Override
-	public Locale resolveLocale(HttpServletRequest request) {
+	public LocaleContext resolveLocaleContext(HttpServletRequest request) {
 		Locale defaultLocale = getDefaultLocale();
 		if (defaultLocale != null && request.getHeader("Accept-Language") == null) {
-			return defaultLocale;
+			return new SimpleLocaleContext(defaultLocale);
 		}
 		Locale requestLocale = request.getLocale();
 		List<Locale> supportedLocales = getSupportedLocales();
 		if (supportedLocales.isEmpty() || supportedLocales.contains(requestLocale)) {
-			return requestLocale;
+			return new SimpleLocaleContext(requestLocale);
 		}
 		Locale supportedLocale = findSupportedLocale(request, supportedLocales);
 		if (supportedLocale != null) {
-			return supportedLocale;
+			return new SimpleLocaleContext(supportedLocale);
 		}
-		return (defaultLocale != null ? defaultLocale : requestLocale);
+		return new SimpleLocaleContext(defaultLocale != null ? defaultLocale : requestLocale);
 	}
 
 	@Nullable
@@ -112,7 +114,8 @@ else if (languageMatch == null) {
 	}
 
 	@Override
-	public void setLocale(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable Locale locale) {
+	public void setLocaleContext(HttpServletRequest request, @Nullable HttpServletResponse response,
+			@Nullable LocaleContext localeContext) {
 		throw new UnsupportedOperationException(
 				"Cannot change HTTP Accept-Language header - use a different locale resolution strategy");
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/CookieLocaleResolver.java

@@ -34,11 +34,11 @@
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
-import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.LocaleContextResolver;
 import org.springframework.web.util.WebUtils;
 
 /**
- * {@link LocaleResolver} implementation that uses a cookie sent back to the user
+ * {@link LocaleContextResolver} implementation that uses a cookie sent back to the user
  * in case of a custom setting, with a fallback to the configured default locale,
  * the request's {@code Accept-Language} header, or the default locale for the server.
  *

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/FixedLocaleResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -27,7 +27,7 @@
 import org.springframework.lang.Nullable;
 
 /**
- * {@link org.springframework.web.servlet.LocaleResolver} implementation
+ * {@link org.springframework.web.servlet.LocaleContextResolver} implementation
  * that always returns a fixed default locale and optionally time zone.
  * Default is the current JVM's default locale.
  *