001/*
002 * Copyright 2002-2017 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.server.i18n;
018
019import org.springframework.context.i18n.LocaleContext;
020import org.springframework.lang.Nullable;
021import org.springframework.web.server.ServerWebExchange;
022
023/**
024 * Interface for web-based locale context resolution strategies that allows
025 * for both locale context resolution via the request and locale context modification
026 * via the HTTP exchange.
027 *
028 * <p>The {@link org.springframework.context.i18n.LocaleContext} object can potentially
029 * includes associated time zone and other locale related information.
030 *
031 * @author Sebastien Deleuze
032 * @since 5.0
033 * @see LocaleContext
034 */
035public interface LocaleContextResolver {
036
037        /**
038         * Resolve the current locale context via the given exchange.
039         * <p>The returned context may be a
040         * {@link org.springframework.context.i18n.TimeZoneAwareLocaleContext},
041         * containing a locale with associated time zone information.
042         * Simply apply an {@code instanceof} check and downcast accordingly.
043         * <p>Custom resolver implementations may also return extra settings in
044         * the returned context, which again can be accessed through downcasting.
045         * @param exchange current server exchange
046         * @return the current locale context (never {@code null})
047         */
048        LocaleContext resolveLocaleContext(ServerWebExchange exchange);
049
050        /**
051         * Set the current locale context to the given one,
052         * potentially including a locale with associated time zone information.
053         * @param exchange current server exchange
054         * @param localeContext the new locale context, or {@code null} to clear the locale
055         * @throws UnsupportedOperationException if the LocaleResolver implementation
056         * does not support dynamic changing of the locale or time zone
057         * @see org.springframework.context.i18n.SimpleLocaleContext
058         * @see org.springframework.context.i18n.SimpleTimeZoneAwareLocaleContext
059         */
060        void setLocaleContext(ServerWebExchange exchange, @Nullable LocaleContext localeContext);
061
062}