LogBackConfigLoader.java

package org.atomhopper;

import java.io.File;
import java.io.IOException;

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

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;

/**
 * Simple Utility class for loading an external config file for logback
 *
 * This code is modified from https://bowerstudios.com/node/896
 */
public class LogBackConfigLoader {

    private Logger logger = LoggerFactory.getLogger(LogBackConfigLoader.class);

    public LogBackConfigLoader(String externalConfigFileLocation) throws IOException, JoranException {
        LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();

        File externalConfigFile = new File(externalConfigFileLocation);
        if (!externalConfigFile.exists()) {
            throw new IOException("Logback External Config File Parameter does not reference a file that exists");
        } else if (!externalConfigFile.isFile()) {
            throw new IOException("Logback External Config File Parameter exists, but does not reference a file");
        } else if (!externalConfigFile.canRead()) {
            throw new IOException("Logback External Config File exists and is a file, but cannot be read.");
        } else {
            JoranConfigurator configurator = new JoranConfigurator();
            configurator.setContext(lc);
            lc.reset();
            configurator.doConfigure(externalConfigFileLocation);

            logger.info("Configured Logback with config file from: " + externalConfigFileLocation);
        }
    }
}