Get variables in the system environment

import org.apache.log4j.Logger;

public class SystemUtil {
	private static final Logger logger = Logger.getLogger(SystemUtil.class);

	/**
	 * Current system environment variable name
	 */
	public static final String SYSTEM_PROPERTY = "BACK_CONFIG";

	/**
	 * Get the configuration file path from the current system environment variables
	 *
	 * @return
	 */
	public static String getConfigPath() {
		return SystemUtil
				.resolveSystemProperty(SystemUtil.SYSTEM_PROPERTY);
	}

	public static String resolveSystemProperty(String key) {
		try {
			String value = System.getProperty(key);
			if (value == null) {
				value = System.getenv(key);
			}
			return value;
		} catch (Throwable ex) {
			logger.error("Failed to get system environment variables, key=" + key, ex);
			return null;
		}
	}
}