/* * Copyright 2002-2018 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. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.server.i18n; import java.util.ArrayList; import java.util.List; import java.util.Locale; import org.springframework.context.i18n.LocaleContext; import org.springframework.context.i18n.SimpleLocaleContext; import org.springframework.http.HttpHeaders; import org.springframework.lang.Nullable; import org.springframework.util.CollectionUtils; import org.springframework.util.StringUtils; import org.springframework.web.server.ServerWebExchange; /** * {@link LocaleContextResolver} implementation that simply uses the primary locale * specified in the "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 #setLocaleContext}, since the accept header * can only be changed through changing the client's locale settings. * * @author Sebastien Deleuze * @author Juergen Hoeller * @since 5.0 */ public class AcceptHeaderLocaleContextResolver implements LocaleContextResolver { private final List<Locale> supportedLocales = new ArrayList<>(4); @Nullable private Locale defaultLocale; /** * Configure supported locales to check against the requested locales * determined via {@link HttpHeaders#getAcceptLanguageAsLocales()}. * @param locales the supported locales */ public void setSupportedLocales(List<Locale> locales) { this.supportedLocales.clear(); this.supportedLocales.addAll(locales); } /** * Return the configured list of supported locales. */ public List<Locale> getSupportedLocales() { return this.supportedLocales; } /** * Configure a fixed default locale to fall back on if the request does not * have an "Accept-Language" header (not set by default). * @param defaultLocale the default locale to use */ public void setDefaultLocale(@Nullable Locale defaultLocale) { this.defaultLocale = defaultLocale; } /** * The configured default locale, if any. */ @Nullable public Locale getDefaultLocale() { return this.defaultLocale; } @Override public LocaleContext resolveLocaleContext(ServerWebExchange exchange) { List<Locale> requestLocales = null; try { requestLocales = exchange.getRequest().getHeaders().getAcceptLanguageAsLocales(); } catch (IllegalArgumentException ex) { // Invalid Accept-Language header: treat as empty for matching purposes } return new SimpleLocaleContext(resolveSupportedLocale(requestLocales)); } @Nullable private Locale resolveSupportedLocale(@Nullable List<Locale> requestLocales) { if (CollectionUtils.isEmpty(requestLocales)) { return this.defaultLocale; // may be null } List<Locale> supportedLocales = getSupportedLocales(); if (supportedLocales.isEmpty()) { return requestLocales.get(0); // never null } Locale languageMatch = null; for (Locale locale : requestLocales) { if (supportedLocales.contains(locale)) { if (languageMatch == null || languageMatch.getLanguage().equals(locale.getLanguage())) { // Full match: language + country, possibly narrowed from earlier language-only match return locale; } } else if (languageMatch == null) { // Let's try to find a language-only match as a fallback for (Locale candidate : supportedLocales) { if (!StringUtils.hasLength(candidate.getCountry()) && candidate.getLanguage().equals(locale.getLanguage())) { languageMatch = candidate; break; } } } } if (languageMatch != null) { return languageMatch; } return (this.defaultLocale != null ? this.defaultLocale : requestLocales.get(0)); } @Override public void setLocaleContext(ServerWebExchange exchange, @Nullable LocaleContext locale) { throw new UnsupportedOperationException( "Cannot change HTTP accept header - use a different locale context resolution strategy"); } }