Spring Framework example source code file (CookieLocaleResolver.java)

This example Spring Framework source code file (CookieLocaleResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

cookie, cookiegenerator, cookielocaleresolver, cookielocaleresolver, default_cookie_name, http, httpservletresponse, locale, locale, locale_request_attribute_name, localeresolver, parsed, parsed, request, response, servlet, string, string, util

The Spring Framework CookieLocaleResolver.java source code

/*
 * Copyright 2002-2007 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.servlet.i18n;

import java.util.Locale;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.util.StringUtils;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.util.CookieGenerator;
import org.springframework.web.util.WebUtils;

/**
 * {@link LocaleResolver} implementation that uses a cookie sent back to the user
 * in case of a custom setting, with a fallback to the specified default locale
 * or the request's accept-header locale.
 *
 * <p>This is particularly useful for stateless applications without user sessions.
 *
 * <p>Custom controllers can thus override the user's locale by calling
 * {@link #setLocale(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.util.Locale)},
 * for example responding to a certain locale change request.
 *
 * @author Juergen Hoeller
 * @author Jean-Pierre Pawlak
 * @since 27.02.2003
 * @see #setDefaultLocale
 * @see #setLocale
 */
public class CookieLocaleResolver extends CookieGenerator implements LocaleResolver {

	/**
	 * The name of the request attribute that holds the locale.
	 * <p>Only used for overriding a cookie value if the locale has been
	 * changed in the course of the current request! Use
	 * {@link org.springframework.web.servlet.support.RequestContext#getLocale}
	 * to retrieve the current locale in controllers or views.
	 * @see org.springframework.web.servlet.support.RequestContext#getLocale
	 */
	public static final String LOCALE_REQUEST_ATTRIBUTE_NAME = CookieLocaleResolver.class.getName() + ".LOCALE";

	/**
	 * The default cookie name used if none is explicitly set.
	 */
	public static final String DEFAULT_COOKIE_NAME = CookieLocaleResolver.class.getName() + ".LOCALE";


	private Locale defaultLocale;


	/**
	 * Creates a new instance of the {@link CookieLocaleResolver} class
	 * using the {@link #DEFAULT_COOKIE_NAME default cookie name}.
	 */
	public CookieLocaleResolver() {
		setCookieName(DEFAULT_COOKIE_NAME);
	}

	/**
	 * Set a fixed Locale that this resolver will return if no cookie found.
	 */
	public void setDefaultLocale(Locale defaultLocale) {
		this.defaultLocale = defaultLocale;
	}

	/**
	 * Return the fixed Locale that this resolver will return if no cookie found,
	 * if any.
	 */
	protected Locale getDefaultLocale() {
		return this.defaultLocale;
	}


	public Locale resolveLocale(HttpServletRequest request) {
		// Check request for pre-parsed or preset locale.
		Locale locale = (Locale) request.getAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME);
		if (locale != null) {
			return locale;
		}

		// Retrieve and parse cookie value.
		Cookie cookie = WebUtils.getCookie(request, getCookieName());
		if (cookie != null) {
			locale = StringUtils.parseLocaleString(cookie.getValue());
			if (logger.isDebugEnabled()) {
				logger.debug("Parsed cookie value [" + cookie.getValue() + "] into locale '" + locale + "'");
			}
			if (locale != null) {
				request.setAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME, locale);
				return locale;
			}
		}

		return determineDefaultLocale(request);
	}

	public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
		if (locale != null) {
			// Set request attribute and add cookie.
			request.setAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME, locale);
			addCookie(response, locale.toString());
		}
		else {
			// Set request attribute to fallback locale and remove cookie.
			request.setAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME, determineDefaultLocale(request));
			removeCookie(response);
		}
	}

	/**
	 * Determine the default locale for the given request,
	 * Called if no locale cookie has been found.
	 * <p>The default implementation returns the specified default locale,
	 * if any, else falls back to the request's accept-header locale.
	 * @param request the request to resolve the locale for
	 * @return the default locale (never <code>null)
	 * @see #setDefaultLocale
	 * @see javax.servlet.http.HttpServletRequest#getLocale()
	 */
	protected Locale determineDefaultLocale(HttpServletRequest request) {
		Locale defaultLocale = getDefaultLocale();
		if (defaultLocale == null) {
			defaultLocale = request.getLocale();
		}
		return defaultLocale;
	}

}