JstlLocalization.java

/***
 * Copyright (c) 2009 Caelum - www.caelum.com.br/opensource
 * All rights reserved.
 *
 * 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 br.com.caelum.vraptor.core;

import java.text.MessageFormat;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import javax.servlet.ServletContext;
import javax.servlet.jsp.jstl.core.Config;
import javax.servlet.jsp.jstl.fmt.LocalizationContext;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import br.com.caelum.vraptor.ioc.RequestScoped;
import br.com.caelum.vraptor.util.EmptyBundle;

import com.google.common.base.Strings;

/**
 * The default implementation of bundle provider uses JSTL's api to access user information on the bundle to be used.
 *
 * @author Guilherme Silveira
 * @author Otávio Scherer Garcia
 */
@RequestScoped
public class JstlLocalization
	implements Localization {

	private static final Logger logger = LoggerFactory.getLogger(JstlLocalization.class);

	private static final String DEFAULT_BUNDLE_NAME = "messages";

	private final RequestInfo request;
	private ResourceBundle bundle;

	public JstlLocalization(RequestInfo request) {
		this.request = request;
	}

	public ResourceBundle getBundle() {
		if (bundle == null) {
			initializeBundle();
		}
	
		return bundle;
	}

	/**
	 * Find the bundle. If the bundle is not found, return an empty for safety operations (avoid
	 * {@link MissingResourceException}.
	 */
	private void initializeBundle() {
		Object bundleLocal = findByKey(Config.FMT_LOCALIZATION_CONTEXT);
		ResourceBundle unsafe = extractUnsafeBundle(bundleLocal);
	
		this.bundle = new SafeResourceBundle(unsafe);
	}

	private ResourceBundle extractUnsafeBundle(Object bundle) {
		if (bundle instanceof String || bundle == null) {
			String baseName = (bundle == null) ? DEFAULT_BUNDLE_NAME : bundle.toString();
	
			try {
			return ResourceBundle.getBundle(baseName, getLocale());
			} catch (MissingResourceException e) {
			logger.debug("couldn't find message bundle, creating an empty one");
			return new EmptyBundle();
			}
	
		}
		if (bundle instanceof LocalizationContext) {
			return ((LocalizationContext) bundle).getResourceBundle();
		}
		logger.warn("Can't handle bundle {}. Please report this bug. Using an empty bundle", bundle);
		return new EmptyBundle();
	}

	public Locale getLocale() {
		return localeFor(Config.FMT_LOCALE);
	}

	public Locale getFallbackLocale() {
		return localeFor(Config.FMT_FALLBACK_LOCALE);
	}

	private Locale localeFor(String key) {
		Object localeValue = findByKey(key);
	
		if (localeValue instanceof String) {
			return findLocalefromString((String) localeValue);
		} else if (localeValue instanceof Locale) {
			return (Locale) localeValue;
		}
	
		return request.getRequest().getLocale();
	}

	/**
	 * Looks up a configuration variable in the request, session and application scopes. If none is found, return by
	 * {@link ServletContext#getInitParameter(String)} method.
	 *
	 * @param key
	 * @return
	 */
	private Object findByKey(String key) {
		Object value = Config.get(request.getRequest(), key);
		if (value != null) {
			return value;
		}
	
		value = Config.get(request.getRequest().getSession(), key);
		if (value != null) {
			return value;
		}
	
		value = Config.get(request.getServletContext(), key);
		if (value != null) {
			return value;
		}
	
		return request.getServletContext().getInitParameter(key);
	}

	public String getMessage(String key, Object... parameters) {
		try {
			String content = getBundle().getString(key);
			return MessageFormat.format(content, parameters);
		} catch (MissingResourceException e) {
			return "???" + key + "???";
		}
	}

	/**
	 * Converts a locale string to {@link Locale}. If the input string is null or empty, return an empty {@link Locale}.
	 *
	 * @param str
	 * @return
	 */
	private Locale findLocalefromString(String str) {
		if (!Strings.isNullOrEmpty(str)) {
			String[] arr = str.split("_");
			if (arr.length == 1) {
			return new Locale(arr[0]);
			} else if (arr.length == 2) {
			return new Locale(arr[0], arr[1]);
	
			} else {
			return new Locale(arr[0], arr[1], arr[2]);
			}
		}
	
		return null;
	}
}