ResourceBundleMessageSource.java

/*
 * Copyright (c) 2009-present the original author or authors.
 *
 * 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 com.planet57.gshell.util.i18n;

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

import com.planet57.gossip.Log;
import org.slf4j.Logger;

import javax.annotation.Nullable;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Message source backed up by {@link ResourceBundle} instances.
 *
 * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @since 2.0
 */
public class ResourceBundleMessageSource
    implements MessageSource
{
  private static final Logger log = Log.getLogger(ResourceBundleMessageSource.class);

  private final List<ResourceBundle> bundles = new LinkedList<>();

  private final Locale locale;

  public ResourceBundleMessageSource(final Locale locale) {
    this.locale = checkNotNull(locale);
  }

  public ResourceBundleMessageSource(final Class... types) {
    this(Locale.getDefault());
    add(types);
  }

  public ResourceBundleMessageSource add(final boolean required, final Class... types) {
    checkNotNull(types);

    for (Class type : types) {
      try {
        ResourceBundle bundle = ResourceBundle.getBundle(type.getName(), locale, type.getClassLoader());
        bundles.add(bundle);
      }
      catch (MissingResourceException e) {
        if (required) {
          throw e;
        }
      }
    }

    return this;
  }

  public Locale getLocale() {
    return locale;
  }

  public ResourceBundleMessageSource add(final Class... types) {
    return add(true, types);
  }

  /**
   * Get a raw message from the resource bundles using the given code.
   */
  public String getMessage(final String code) {
    checkNotNull(code);

    for (ResourceBundle bundle : bundles) {
      try {
        return bundle.getString(code);
      }
      catch (MissingResourceException e) {
        log.trace(e.toString(), e);
      }
    }

    throw new ResourceNotFoundException(code);
  }

  /**
   * Format a message (based on {@link MessageFormat} using the message
   * from the resource bundles using the given code as a pattern and the
   * given objects as arguments.
   */
  public String format(final String code, @Nullable final Object... args) {
    String pattern = getMessage(code);
    if (args != null) {
      return String.format(pattern, args);
    }
    else {
      return pattern;
    }
  }
}