001/*
002 * Copyright 2002-2019 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.servlet.i18n;
018
019import java.util.Locale;
020
021import javax.servlet.ServletException;
022import javax.servlet.http.HttpServletRequest;
023import javax.servlet.http.HttpServletResponse;
024
025import org.apache.commons.logging.Log;
026import org.apache.commons.logging.LogFactory;
027
028import org.springframework.lang.Nullable;
029import org.springframework.util.ObjectUtils;
030import org.springframework.util.StringUtils;
031import org.springframework.web.servlet.LocaleResolver;
032import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
033import org.springframework.web.servlet.support.RequestContextUtils;
034
035/**
036 * Interceptor that allows for changing the current locale on every request,
037 * via a configurable request parameter (default parameter name: "locale").
038 *
039 * @author Juergen Hoeller
040 * @author Rossen Stoyanchev
041 * @since 20.06.2003
042 * @see org.springframework.web.servlet.LocaleResolver
043 */
044public class LocaleChangeInterceptor extends HandlerInterceptorAdapter {
045
046        /**
047         * Default name of the locale specification parameter: "locale".
048         */
049        public static final String DEFAULT_PARAM_NAME = "locale";
050
051
052        protected final Log logger = LogFactory.getLog(getClass());
053
054        private String paramName = DEFAULT_PARAM_NAME;
055
056        @Nullable
057        private String[] httpMethods;
058
059        private boolean ignoreInvalidLocale = false;
060
061
062        /**
063         * Set the name of the parameter that contains a locale specification
064         * in a locale change request. Default is "locale".
065         */
066        public void setParamName(String paramName) {
067                this.paramName = paramName;
068        }
069
070        /**
071         * Return the name of the parameter that contains a locale specification
072         * in a locale change request.
073         */
074        public String getParamName() {
075                return this.paramName;
076        }
077
078        /**
079         * Configure the HTTP method(s) over which the locale can be changed.
080         * @param httpMethods the methods
081         * @since 4.2
082         */
083        public void setHttpMethods(@Nullable String... httpMethods) {
084                this.httpMethods = httpMethods;
085        }
086
087        /**
088         * Return the configured HTTP methods.
089         * @since 4.2
090         */
091        @Nullable
092        public String[] getHttpMethods() {
093                return this.httpMethods;
094        }
095
096        /**
097         * Set whether to ignore an invalid value for the locale parameter.
098         * @since 4.2.2
099         */
100        public void setIgnoreInvalidLocale(boolean ignoreInvalidLocale) {
101                this.ignoreInvalidLocale = ignoreInvalidLocale;
102        }
103
104        /**
105         * Return whether to ignore an invalid value for the locale parameter.
106         * @since 4.2.2
107         */
108        public boolean isIgnoreInvalidLocale() {
109                return this.ignoreInvalidLocale;
110        }
111
112        /**
113         * Specify whether to parse request parameter values as BCP 47 language tags
114         * instead of Java's legacy locale specification format.
115         * <p><b>NOTE: As of 5.1, this resolver leniently accepts the legacy
116         * {@link Locale#toString} format as well as BCP 47 language tags.</b>
117         * @since 4.3
118         * @see Locale#forLanguageTag(String)
119         * @see Locale#toLanguageTag()
120         * @deprecated as of 5.1 since it only accepts {@code true} now
121         */
122        @Deprecated
123        public void setLanguageTagCompliant(boolean languageTagCompliant) {
124                if (!languageTagCompliant) {
125                        throw new IllegalArgumentException("LocaleChangeInterceptor always accepts BCP 47 language tags");
126                }
127        }
128
129        /**
130         * Return whether to use BCP 47 language tags instead of Java's legacy
131         * locale specification format.
132         * @since 4.3
133         * @deprecated as of 5.1 since it always returns {@code true} now
134         */
135        @Deprecated
136        public boolean isLanguageTagCompliant() {
137                return true;
138        }
139
140
141        @Override
142        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
143                        throws ServletException {
144
145                String newLocale = request.getParameter(getParamName());
146                if (newLocale != null) {
147                        if (checkHttpMethod(request.getMethod())) {
148                                LocaleResolver localeResolver = RequestContextUtils.getLocaleResolver(request);
149                                if (localeResolver == null) {
150                                        throw new IllegalStateException(
151                                                        "No LocaleResolver found: not in a DispatcherServlet request?");
152                                }
153                                try {
154                                        localeResolver.setLocale(request, response, parseLocaleValue(newLocale));
155                                }
156                                catch (IllegalArgumentException ex) {
157                                        if (isIgnoreInvalidLocale()) {
158                                                if (logger.isDebugEnabled()) {
159                                                        logger.debug("Ignoring invalid locale value [" + newLocale + "]: " + ex.getMessage());
160                                                }
161                                        }
162                                        else {
163                                                throw ex;
164                                        }
165                                }
166                        }
167                }
168                // Proceed in any case.
169                return true;
170        }
171
172        private boolean checkHttpMethod(String currentMethod) {
173                String[] configuredMethods = getHttpMethods();
174                if (ObjectUtils.isEmpty(configuredMethods)) {
175                        return true;
176                }
177                for (String configuredMethod : configuredMethods) {
178                        if (configuredMethod.equalsIgnoreCase(currentMethod)) {
179                                return true;
180                        }
181                }
182                return false;
183        }
184
185        /**
186         * Parse the given locale value as coming from a request parameter.
187         * <p>The default implementation calls {@link StringUtils#parseLocale(String)},
188         * accepting the {@link Locale#toString} format as well as BCP 47 language tags.
189         * @param localeValue the locale value to parse
190         * @return the corresponding {@code Locale} instance
191         * @since 4.3
192         */
193        @Nullable
194        protected Locale parseLocaleValue(String localeValue) {
195                return StringUtils.parseLocale(localeValue);
196        }
197
198}