Refactor HttpHeaders "Accept-Language" with Locale

spring-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -457,47 +457,43 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	}
 
 	/**
-	 * Return the acceptable language ranges from the
-	 * {@literal Accept-Language} header
-	 * <p>If you only need the most preferred locale use
-	 * {@link #getAcceptLanguageAsLocale()} or if you need to filter based on
-	 * a list of supporeted locales you can pass the returned list to
+	 * Return the language ranges from the {@literal "Accept-Language"} header.
+	 * <p>If you only need sorted, preferred locales only use
+	 * {@link #getAcceptLanguageAsLocales()} or if you need to filter based on
+	 * a list of supported locales you can pass the returned list to
 	 * {@link Locale#filter(List, Collection)}.
 	 * @since 5.0
 	 */
 	public List<Locale.LanguageRange> getAcceptLanguage() {
 		String value = getFirst(ACCEPT_LANGUAGE);
-		if (value != null) {
-			return Locale.LanguageRange.parse(value);
-		}
-		return Collections.emptyList();
+		return value != null ? Locale.LanguageRange.parse(value) : Collections.emptyList();
 	}
 
 	/**
-	 * A variant of {@link #setAcceptLanguage(List)} that sets the {@literal Accept-Language}
-	 * header value to the specified locale.
+	 * Variant of {@link #setAcceptLanguage(List)} using {@link Locale}'s.
 	 * @since 5.0
 	 */
-	public void setAcceptLanguageAsLocale(Locale locale) {
-		setAcceptLanguage(Collections.singletonList(new Locale.LanguageRange(locale.toLanguageTag())));
+	public void setAcceptLanguageAsLocales(List<Locale> locales) {
+		setAcceptLanguage(locales.stream()
+				.map(locale -> new Locale.LanguageRange(locale.toLanguageTag()))
+				.collect(Collectors.toList()));
 	}
 
 	/**
 	 * A variant of {@link #getAcceptLanguage()} that converts each
-	 * {@link java.util.Locale.LanguageRange} to a {@link Locale} and returns
-	 * the first one on the list.
+	 * {@link java.util.Locale.LanguageRange} to a {@link Locale}.
+	 * @return the locales or an empty list
 	 * @since 5.0
 	 */
-	public Locale getAcceptLanguageAsLocale() {
+	public List<Locale> getAcceptLanguageAsLocales() {
 		List<Locale.LanguageRange> ranges = getAcceptLanguage();
 		if (ranges.isEmpty()) {
-			return null;
+			return Collections.emptyList();
 		}
 		return ranges.stream()
 				.map(range -> Locale.forLanguageTag(range.getRange()))
 				.filter(locale -> StringUtils.hasText(locale.getDisplayName()))
-				.findFirst()
-				.orElse(null);
+				.collect(Collectors.toList());
 	}
 
 	/**

spring-web/src/test/java/org/springframework/http/HttpHeadersTests.java

@@ -34,8 +34,13 @@ import java.util.TimeZone;
 import org.hamcrest.Matchers;
 import org.junit.Test;
 
-import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Unit tests for {@link org.springframework.http.HttpHeaders}.
@@ -436,11 +441,10 @@ public class HttpHeadersTests {
 				new Locale.LanguageRange("*", 0.5)
 		);
 		assertEquals(expectedRanges, headers.getAcceptLanguage());
+		assertEquals(Locale.forLanguageTag("fr-ch"), headers.getAcceptLanguageAsLocales().get(0));
 
-		assertEquals(Locale.forLanguageTag("fr-ch"), headers.getAcceptLanguageAsLocale());
-
-		headers.setAcceptLanguageAsLocale(Locale.FRANCE);
-		assertEquals(Locale.FRANCE, headers.getAcceptLanguageAsLocale());
+		headers.setAcceptLanguageAsLocales(Collections.singletonList(Locale.FRANCE));
+		assertEquals(Locale.FRANCE, headers.getAcceptLanguageAsLocales().get(0));
 	}
 
 	@Test

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/RequestContext.java

@@ -82,8 +82,8 @@ public class RequestContext {
 		this.model = model;
 		this.messageSource = messageSource;
 
-		Locale acceptLocale = exchange.getRequest().getHeaders().getAcceptLanguageAsLocale();
-		this.locale = acceptLocale != null ? acceptLocale : Locale.getDefault();
+		List<Locale> locales = exchange.getRequest().getHeaders().getAcceptLanguageAsLocales();
+		this.locale = locales.isEmpty() ? Locale.getDefault() : locales.get(0);
 		this.timeZone = TimeZone.getDefault(); // TODO
 
 		this.defaultHtmlEscape = null; // TODO

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandler.java

@@ -200,8 +200,8 @@ public class ViewResolutionResultHandler extends HandlerResultHandlerSupport
 					Model model = result.getModel();
 					MethodParameter parameter = result.getReturnTypeSource();
 
-					Locale acceptLocale = exchange.getRequest().getHeaders().getAcceptLanguageAsLocale();
-					Locale locale = acceptLocale != null ? acceptLocale : Locale.getDefault();
+					List<Locale> locales = exchange.getRequest().getHeaders().getAcceptLanguageAsLocales();
+					Locale locale = locales.isEmpty() ? Locale.getDefault() : locales.get(0);
 
 					Class<?> clazz = valueType.getRawClass();
 					if (clazz == null) {

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/freemarker/FreeMarkerView.java

@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
 import java.nio.charset.Charset;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
@@ -171,8 +172,8 @@ public class FreeMarkerView extends AbstractUrlBasedView {
 			logger.debug("Rendering FreeMarker template [" + getUrl() + "].");
 		}
 
-		Locale acceptLocale = exchange.getRequest().getHeaders().getAcceptLanguageAsLocale();
-		Locale locale = acceptLocale != null ? acceptLocale : Locale.getDefault();
+		List<Locale> locales = exchange.getRequest().getHeaders().getAcceptLanguageAsLocales();
+		Locale locale = locales.isEmpty() ? Locale.getDefault() : locales.get(0);
 
 		DataBuffer dataBuffer = exchange.getResponse().bufferFactory().allocateBuffer();
 		try {