ConfigFileFinder.java

/*
 * (C) Copyright 2016 Kurento (http://kurento.org/)
 *
 * 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 org.kurento.commons;

import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

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

public class ConfigFileFinder {

  private static final Logger log = LoggerFactory.getLogger(ConfigFilePropertyHolder.class);

  private static final String DEFAULT_KURENTO_CONF_FILE_NAME = "kurento.conf.json";

  public static Path searchDefaultConfigFile() throws IOException {
    return searchConfigFileInDefaultPlaces(DEFAULT_KURENTO_CONF_FILE_NAME);
  }

  public static Path searchConfigFileInDefaultPlaces(String configFileName) throws IOException {

    if (configFileName == null) {
      configFileName = DEFAULT_KURENTO_CONF_FILE_NAME;
    }

    Path path = getPathFromFile(configFileName);

    if (path == null) {
      log.warn("Config file '" + configFileName + "' not found. Searching places are:"
          + "1) A /config subdir of the current directory." + "2) The current directory."
          + "3) A classpath /config package." + "4) The classpath root");
      return null;
    }

    return path;
  }

  /**
   * The config file will be searched in the following places:
   * <ul>
   * <li>1. A /config subdir of the current directory.</li>
   * <li>2. The current directory</li>
   * <li>3. A classpath /config package</li>
   * <li>4. The classpath root</li>
   * </ul>
   * </p>
   * The list is ordered by precedence (locations higher in the list override lower items).
   * </p>
   * Remember that a property can be set using Java System properties (java -Dprop=value -jar
   * file.jar)
   *
   * @param fileName
   *          The name of the file
   * @return the path
   * @throws URISyntaxException
   *           if the file name does not have the correct format
   * @throws IOException
   *           if the file does not exist
   */
  private static Path getPathFromFile(String fileName) throws IOException {

    Path path = Paths.get("config", fileName);

    if (Files.exists(path)) {
      return path;
    }

    path = Paths.get(fileName);

    if (Files.exists(path)) {
      return path;
    }

    path = ClassPath.get("/config/" + fileName);

    if (path != null) {
      return path;
    }

    path = ClassPath.get("/" + fileName);

    if (path != null) {
      return path;
    }

    return null;
  }

}