StringManager.java Source code

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Here is the source code for StringManager.java

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/*
 * Copyright (C) 2003 Colin Bell
 * colbell@users.sourceforge.net
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.text.MessageFormat;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import java.net.URLClassLoader;
import java.net.URL;

/**
 * This class defines i18nized strings. These strings are stored in a file
 * with a base name I18NStrings.properties in each package directory.
 *
 * @author <A HREF="mailto:colbell@users.sourceforge.net">Colin Bell</A>
 */
public class StringManager {

    /** Contains the localised strings. */
    private ResourceBundle _rsrcBundle;
    private String _bundleBaseName;
    private URL[] _bundleLoaderUrLs = new URL[0];

    /** a flag to indicate whether or not to throw exception for missing resource string */
    private static boolean _testMode = false;

    /**
     * Ctor specifying the package name. Attempt to load a resource bundle
     * from the package directory.
     *
     * @param packageName Name of package
     * @param classLoader Class loader to use
     */
    StringManager(String packageName, ClassLoader loader) {
        super();
        _bundleBaseName = packageName + ".I18NStrings";
        _rsrcBundle = ResourceBundle.getBundle(_bundleBaseName, Locale.getDefault(), loader);

        if (loader instanceof URLClassLoader) {
            _bundleLoaderUrLs = ((URLClassLoader) loader).getURLs();
        }

    }

    /**
     * Retrieve the localized string for the passed key. If it isn't found
     * an error message is returned instead.
     *
     * @param key   Key to retrieve string for.
     *
     * @return  Localized string or error message.
     *
     * @throws  IllegalArgumentException
     *      Thrown if <TT>null</TT> <TT>key</TT> passed.
     */
    public String getString(String key) {
        if (key == null) {
            throw new IllegalArgumentException("key == null");
        }

        try {
            return _rsrcBundle.getString(key);
        } catch (MissingResourceException ex) {
            StringBuilder sb = new StringBuilder();
            sb.append("No resource string found for key '" + key + "' in bundle " + _bundleBaseName + "\n\n");

            if (0 < _bundleLoaderUrLs.length) {
                sb.append("The following classpath entries are available to the bundle loader:\n");
                for (int i = 0; i < _bundleLoaderUrLs.length; i++) {
                    sb.append(_bundleLoaderUrLs[i]).append("\n");
                }
            }

            if (_testMode) {
                throw new IllegalStateException(sb.toString());
            }
            return "No resource found for key " + key;
        }
    }

    /**
     * Retrieve the localized string for the passed key and format it with the
     * passed arguments.
     *
     * @param   key     Key to retrieve string for.
     * @param   args    Any string arguments that should be used as values to 
     *                  parameters found in the localized string.
     *                   
     * @return  Localized string or error message.
     *
     * @throws  IllegalArgumentException
     *          Thrown if <TT>null</TT> <TT>key</TT> passed.
     */
    public String getString(String key, String[] args) {
        return getString(key, (Object[]) args);
    }

    /**
     * Retrieve the localized string for the passed key and format it with the
     * passed arguments.
     *
     * @param key   Key to retrieve string for.
       * @param   args    Any string arguments that should be used as values to 
       *                  parameters found in the localized string. 
     *
     * @return  Localized string or error message.
     *
     * @throws  IllegalArgumentException
     *      Thrown if <TT>null</TT> <TT>key</TT> passed.
     */
    public String getString(String key, Object... args) {
        if (key == null) {
            throw new IllegalArgumentException("key == null");
        }

        if (args == null) {
            args = new Object[0];
        }

        final String str = getString(key);
        try {
            return MessageFormat.format(str, args);
        } catch (IllegalArgumentException ex) {
            String msg = "Error formatting i18 string. Key is '" + key + "'";

            return msg + ": " + ex.toString();
        }
    }

    /**
     * Allows the caller to enable/disable test mode which results in an exception being thrown for no 
     * resource string defined. 
     * 
     * @param enabled 
     */
    public static void setTestMode(boolean enabled) {
        _testMode = enabled;
    }
}