ConfigReader.java

package utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Map.Entry;
import java.util.Properties;

import util.Util;

public class ConfigReader {

	protected static Properties properties;
	protected static String configFile;

	/*******************************************
	 * Load configuration e.g. params (enable parallel), file path Allows
	 * substitutions like these: $global-variable$
	 * 
	 * @param configFileIn
	 *            "./data/config/config.properties"
	 * @throws IOException
	 *             : configFile cannot be loaded.
	 *******************************************/
	public static boolean loadConfig(String configFileIn) throws IOException {
		// load once as initialization
		if (properties == null || configFile == null) {
			if (!Util.exists(configFileIn))
				return false;

			Properties firstPass = new Properties();
			properties = new Properties();
			firstPass.load(new FileInputStream(new File(configFileIn)));
			// second pass to fill out constants.
			for (Entry<Object, Object> e : firstPass.entrySet()) {

				String key = e.getKey().toString();
				String val = firstPass.getProperty(key);

				if (Util.countChar(val, '$', false) > 1) {
					// won't create path inside writeFile if path doesn't exist
					char[] chs = val.toCharArray();

					StringBuilder k2 = new StringBuilder();
					StringBuilder v2 = new StringBuilder();
					for (int i = 0; i < chs.length; i++) {

						if (chs[i] == '$') {
							for (int j = i + 1; j < chs.length; j++) {
								if (chs[j] != '$') {
									k2.append(chs[j]);
								} else {
									// only one indirection possible.
									k2 =
										new StringBuilder().append(firstPass
											.getProperty(k2.toString()));
									v2.append(k2);
									k2 = new StringBuilder();
									i = j;
									break;
								}
							}
						} else
							v2.append(chs[i]);
					}

					properties.put(key, v2.toString());
				} else
					properties.put(key, val);
			}
		}

		return properties != null;
	}

	public static String getProperty(String p) throws IOException {
		return getProperty(p, "");
	}

	public static String getProperty(String p, String defaultVal) {
		try {
			if (properties == null) {
				boolean isLoaded = loadConfig(configFile);
				if (!isLoaded)
					return defaultVal;
			}
			return properties.getProperty(p);
		} catch (Exception e) {
			return defaultVal;
		}
	}

	public static String setProperty(String propertykey, String value)
		throws IOException {
		if (properties == null)
			loadConfig(configFile);
		return (String) properties.setProperty(propertykey, value);
	}

}