com.aspectran.web.support.i18n.locale.AcceptHeaderLocaleResolver Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2025 The Aspectran Project
*
* 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 com.aspectran.web.support.i18n.locale;
import com.aspectran.core.activity.Translet;
import com.aspectran.core.support.i18n.locale.AbstractLocaleResolver;
import com.aspectran.core.support.i18n.locale.LocaleResolver;
import com.aspectran.utils.StringUtils;
import com.aspectran.utils.annotation.jsr305.NonNull;
import com.aspectran.utils.annotation.jsr305.Nullable;
import com.aspectran.web.support.http.HttpHeaders;
import jakarta.servlet.http.HttpServletRequest;
import java.util.Enumeration;
import java.util.List;
import java.util.Locale;
import java.util.TimeZone;
/**
* This class is a clone of org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver
*
* {@link LocaleResolver} implementation that looks for a match between locales
* in the {@code Accept-Language} header and a list of configured supported
* locales.
*
*
See {@link #setSupportedLocales(List)} for further details on how
* supported and requested locales are matched.
*
*
Note: This implementation does not support {@link #setLocale} since the
* {@code Accept-Language} header can only be changed by changing the client's
* locale settings.
*/
public class AcceptHeaderLocaleResolver extends AbstractLocaleResolver {
@Override
public Locale resolveLocale(Translet translet) {
Locale defaultLocale = getDefaultLocale();
if (defaultLocale != null && translet.getRequestAdapter().getHeader(HttpHeaders.ACCEPT_LANGUAGE) == null) {
return defaultLocale;
}
Locale requestLocale = translet.getRequestAdapter().getLocale();
List supportedLocales = getSupportedLocales();
if (supportedLocales == null || supportedLocales.isEmpty() || supportedLocales.contains(requestLocale)) {
return requestLocale;
}
Locale supportedLocale = findSupportedLocale(translet.getResponseAdapter().getAdaptee(), supportedLocales);
if (supportedLocale != null) {
return supportedLocale;
}
return (defaultLocale != null ? defaultLocale : requestLocale);
}
@Override
public TimeZone resolveTimeZone(Translet translet) {
return determineDefaultTimeZone(translet);
}
@Nullable
private Locale findSupportedLocale(@NonNull HttpServletRequest request, List supportedLocales) {
Enumeration requestLocales = request.getLocales();
Locale languageMatch = null;
while (requestLocales.hasMoreElements()) {
Locale locale = requestLocales.nextElement();
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 supportedLocale : supportedLocales) {
if (!StringUtils.hasLength(supportedLocale.getCountry()) &&
supportedLocale.getLanguage().equals(locale.getLanguage())) {
languageMatch = supportedLocale;
break;
}
}
}
}
return languageMatch;
}
@Override
public void setLocale(Translet translet, Locale locale) {
throw new UnsupportedOperationException(
"Cannot change HTTP Accept-Language header - use a different locale resolution strategy");
}
@Override
public void setTimeZone(@NonNull Translet translet, TimeZone timeZone) {
translet.getRequestAdapter().setTimeZone(timeZone);
}
}