org.springframework.web.server.i18n.AcceptHeaderLocaleContextResolver Maven / Gradle / Ivy
/*
* Copyright 2002-2020 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
*
* https://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).
*
* 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
* @see HttpHeaders#getAcceptLanguageAsLocales()
*/
public class AcceptHeaderLocaleContextResolver implements LocaleContextResolver {
private final List 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 locales) {
this.supportedLocales.clear();
this.supportedLocales.addAll(locales);
}
/**
* Return the configured list of supported locales.
*/
public List 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.
* This method may be overridden in subclasses.
*/
@Nullable
public Locale getDefaultLocale() {
return this.defaultLocale;
}
@Override
public LocaleContext resolveLocaleContext(ServerWebExchange exchange) {
List 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 requestLocales) {
if (CollectionUtils.isEmpty(requestLocales)) {
return getDefaultLocale(); // may be null
}
List 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;
}
Locale defaultLocale = getDefaultLocale();
return (defaultLocale != null ? 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");
}
}