localeaction.java

Enjoy Web Dev With Tapestry 一书的源代码

/*
 * $Header: /home/cvs/jakarta-struts/src/example/org/apache/struts/webapp/example/LocaleAction.java,v 1.3 2004/03/12 02:43:29 husted Exp $
 * $Revision: 1.3 $
 * $Date: 2004/03/12 02:43:29 $
 *
 * Copyright 2000-2004 Apache Software Foundation
 *
 * 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.apache.struts.webapp.example;

import java.util.Locale;

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

import org.apache.struts.Globals;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

/**
 * <p>
 * Change user's Struts
 * 
 * @link(java.util.Locale).
 * </p>
 */
public final class LocaleAction extends BaseAction {

	/**
	 * <p>
	 * Return true if parameter is null or trims to empty.
	 * </p>
	 * 
	 * @param string
	 *            The string to text; may be null
	 * @return true if parameter is null or empty
	 */
	private boolean isBlank(String string) {
		return ((string == null) || (string.trim().length() == 0));
	}

	/**
	 * <p>
	 * Parameter for
	 * 
	 * @link(java.util.Locale) language property. ["language"]
	 *                         </p>
	 */
	private static final String LANGUAGE = "language";

	/**
	 * <p>
	 * Parameter for
	 * 
	 * @link(java.util.Locale) country property. ["country"]
	 *                         </p>
	 */
	private static final String COUNTRY = "country";

	/**
	 * <p>
	 * Parameter for response page URI. ["page"]
	 * </p>
	 */
	private static final String PAGE = "page";

	/**
	 * <p>
	 * Parameter for response forward name. ["forward"]
	 * </p>
	 */
	private static final String FORWARD = "forward";

	/**
	 * <p>
	 * Logging message if LocaleAction is missing a target parameter.
	 * </p>
	 */
	private static final String LOCALE_LOG = "LocaleAction: Missing page or forward parameter";

	/**
	 * <p>
	 * Change the user's Struts
	 * 
	 * @link(java.util.Locale) based on request parameters for "language",
	 *                         "country". After setting the Locale, control is
	 *                         forwarded to an URI path indicated by a "page"
	 *                         parameter, or a forward indicated by a "forward"
	 *                         parameter, or to a forward given as the mappings
	 *                         "parameter" property. The response location must
	 *                         be specified one of these ways.
	 *                         </p>
	 * @param mapping
	 *            The ActionMapping used to select this instance
	 * @param form
	 *            The optional ActionForm bean for this request (if any)
	 * @param request
	 *            The HTTP request we are processing
	 * @param response
	 *            The HTTP response we are creating
	 * 
	 * @return An ActionForward indicate the resources that will render the
	 *         response
	 * @exception Exception
	 *                if an input/output error or servlet exception occurs
	 */
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		String language = request.getParameter(LANGUAGE);
		String country = request.getParameter(COUNTRY);

		Locale locale = getLocale(request);

		if ((!isBlank(language)) && (!isBlank(country))) {
			locale = new Locale(language, country);
		} else if (!isBlank(language)) {
			locale = new Locale(language, "");
		}

		HttpSession session = request.getSession();
		session.setAttribute(Globals.LOCALE_KEY, locale);

		String target = request.getParameter(PAGE);
		if (!isBlank(target))
			return new ActionForward(target);

		target = request.getParameter(FORWARD);
		if (isBlank(target))
			target = mapping.getParameter();
		if (isBlank(target)) {
			log.warn(LOCALE_LOG);
			return null;
		}
		return mapping.findForward(target);
	}
}