CustomMessageResolver.java

package org.ff4j.web.console;

/*
 * #%L
 * ff4j-web
 * %%
 * Copyright (C) 2013 - 2016 FF4J
 * %%
 * 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.
 * #L%
 */


import java.io.IOException;
import java.io.InputStream;
import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.thymeleaf.Arguments;
import org.thymeleaf.messageresolver.IMessageResolver;
import org.thymeleaf.messageresolver.MessageResolution;

/**
 * All message in the same properties file embedded.
 *
 * @author Cedrick LUNVEN (@clunven)
 */
public class CustomMessageResolver implements IMessageResolver {
	
	/** Name of property file. */
	private static final String MSG_FILE = "ff4j-messages";
	
	/** Name of property file. */
	private static final String MSG_FILE_EXTENSION = ".properties";
	
	/** Logger for this class. */
    public static final Logger LOGGER = LoggerFactory.getLogger(CustomMessageResolver.class);
   
	/** Properties per Locale. */
    protected Map < String , Properties > messages = new HashMap< String, Properties >();
    
    /** Default properties "messages.properties". */
    protected final Properties defaultMessages;
    
    public CustomMessageResolver() {
    	super();
        this.defaultMessages = new Properties();
    }
    
	/** {@inheritDoc} */
	public void initialize() {
		try {
			defaultMessages.load(
					CustomMessageResolver.class.getClassLoader()
						.getResourceAsStream(MSG_FILE + MSG_FILE_EXTENSION));
		} catch (IOException e) {
			LOGGER.error("Cannot load properties", e);
		}
	}
	
	/**
	 * Load property file from locale and put in cache.
	 *
	 * @param locale
	 * 		current locale
	 * @return
	 * 		target properties
	 */
	private Properties resolveProperties(Locale locale) {
		if (!messages.containsKey(locale.getLanguage())) {
			String expectedFileName = MSG_FILE + "_" + locale.getLanguage() + MSG_FILE_EXTENSION;
			InputStream is = CustomMessageResolver.class.getClassLoader().getResourceAsStream(expectedFileName);
			messages.put(locale.getLanguage(), null);
			if (is != null) {
				try {
					Properties propsLocale = new Properties();
					propsLocale.load(is);
					messages.put(locale.getLanguage(), propsLocale);
				} catch (IOException e) {
					LOGGER.error("Cannot load properties", e);
				}
			}
        }
		Properties target = messages.get(locale.getLanguage());
		return target != null ? target : defaultMessages;
	}
	
	/** {@inheritDoc} */
	public MessageResolution resolveMessage(Arguments args, String key, Object[] msgParams) {
		final Locale locale = args.getContext().getLocale();
        String targetMsg = resolveProperties(locale).getProperty(key);
		if (targetMsg == null) {
			targetMsg = "<span style=\"color:red\">" + key + " not found</span>";
		} else if (msgParams != null && msgParams.length > 0) {
			targetMsg = new MessageFormat(targetMsg, args.getContext().getLocale()).format(msgParams);
		}
		return new MessageResolution(targetMsg);
	}	

	/** {@inheritDoc} */
	public Integer getOrder() {
		return 0;
	}

	/** {@inheritDoc} */
	public String getName() {
		return "customMessageResolver";
	}
}