CompSystemI18n.java

/*******************************************************************************
 * Copyright (c) 2004, 2010 BREDEX GmbH.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     BREDEX GmbH - initial API and implementation and/or initial documentation
 *******************************************************************************/
package org.eclipse.jubula.tools.internal.i18n;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.PropertyResourceBundle;
import java.util.ResourceBundle;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Class to internationalize all CompSystem strings
 * @author BREDEX GmbH
 * @created 02.01.2007
 */
public class CompSystemI18n {  
    /** the logger */
    private static Logger log = LoggerFactory.getLogger(CompSystemI18n.class);
    
    /** List of ResourceBundles */
    private static final List<ResourceBundle> PLUGIN_BUNDLES = 
        new LinkedList<ResourceBundle>();
    
    /** 
     * mapping from i18n keys (String) to i18n values (String)
     */
    private static final Map<String, String> I18N_MAP = 
        new HashMap<String, String>();
    
    /**
     * Constructor
     */
    private CompSystemI18n() {
        // private constructor to prevent instantiation of class utility
    }
    
    /**
     * Adds the given {@link ResourceBundle}
     * @param bundle a {@link ResourceBundle}
     */
    public static void addResourceBundle(ResourceBundle bundle) {
        if (bundle == null) {
            log.error("ResourceBundle is null!"); //$NON-NLS-1$
            return;
        }
        PLUGIN_BUNDLES.add(bundle);
    }
    
    /**
     * Gets the internationalized String by a given key.
     * 
     * @param key
     *            the key for the internationalized String.
     * @return a internationalized <code>String</code>.
     */
    public static String getString(String key) {
        return getString(key, false);
    }

    /**
     * Gets the internationalized String by a given key.
     * 
     * @param key
     *            the key for the internationalized String.
     * @param fallBack
     *            returns the key if no value found
     * @return a internationalized <code>String</code>.
     */
    public static String getString(String key, boolean fallBack) {
        try {
            return getStringInternal(key);
        } catch (MissingResourceException mre) {
            if (!fallBack) {
                logError(key, mre);
            }
        }
        return key;
    }
    
    /**
     * Logs in error log
     * 
     * @param key
     *            the I18n-key
     * @param throwable
     *            the throwable
     */
    static void logError(String key, Throwable throwable) {
        log.error("Cannot find I18N-key in resource bundles: " + key, throwable); //$NON-NLS-1$
    }
    
    /**
     * Searches for the value of the given key in all bundles.<br>
     * throws MissingResourceException if the key was not found. 
     * @param key the key
     * @return the value for the given key
     */
    private static String getStringInternal(String key) {
        
        if (key == null) {
            return StringUtils.EMPTY;
        }
        
        String value = I18N_MAP.get(key);
        if (value != null) {
            return value;
        }

        Iterator<ResourceBundle> bundleIter = PLUGIN_BUNDLES.iterator();
        while (bundleIter.hasNext()) {
            ResourceBundle bundle = bundleIter.next();
            try {
                value = bundle.getString(key);
                I18N_MAP.put(key, value);
                return value;
            } catch (MissingResourceException ex) {
                // ok here, we search in multiple bundles
            }
        }
        
        I18N_MAP.put(key, key);
        throw new MissingResourceException("No entry found for key: " + key, //$NON-NLS-1$
            CompSystemI18n.class.getName(), key);
    }
    
    /**
     * 
     * @return a String representation of the ResourceBundles to use for
     * fromString(String string)
     * @see fromString(String string)
     */
    public static String bundlesToString() {
        final String keyValueSeparator = "="; //$NON-NLS-1$
        final String lineBreak = "\n"; //$NON-NLS-1$
        final StringBuffer entries = new StringBuffer();
        for (Iterator<ResourceBundle> bundlesIt = PLUGIN_BUNDLES.iterator(); 
            bundlesIt.hasNext();) {
            
            final ResourceBundle bundle = bundlesIt.next();
            for (Enumeration keys = bundle.getKeys(); keys.hasMoreElements();) {
                final String key = String.valueOf(keys.nextElement());
                final String value = bundle.getString(key);
                entries.append(key)
                        .append(keyValueSeparator)
                        .append(value)
                        .append(lineBreak);
            }
        }
        return entries.toString();
    }
    
    /**
     * Creates a ResourceBundle from the given String.<br>
     * The given String must have the specification of a properties-file:<br>
     * key=value<br>
     * key=value<br>
     * ...<br>
     * with a line break (\n) after every value.
     * @param string a String from bundleToString
     */
    public static void fromString(String string) {
        final ByteArrayInputStream stream = new ByteArrayInputStream(
            string.getBytes());
        try {
            final PropertyResourceBundle bundle = new PropertyResourceBundle(
                stream);
            PLUGIN_BUNDLES.clear();
            addResourceBundle(bundle);
        } catch (IOException e) {
            log.error(e.getLocalizedMessage(), e);
        }
    }

}