org.opensubsystems.pattern.parameter.util.XMLConfig.java Source code

Introduction

Here is the source code for org.opensubsystems.pattern.parameter.util.XMLConfig.java

Source

/*
 * Copyright (C) 2011 - 2014 OpenSubsystems.com/net/org and its owners. All rights reserved.
 * 
 * This file is part of OpenSubsystems.
 *
 * OpenSubsystems is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. 
 */

package org.opensubsystems.pattern.parameter.util;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.commons.digester3.Digester;
import org.apache.commons.digester3.binder.DigesterLoader;
import org.opensubsystems.core.error.OSSConfigException;
import org.opensubsystems.core.util.FileUtils;
import org.opensubsystems.core.util.Log;
import org.opensubsystems.core.util.OSSObject;
import org.opensubsystems.core.util.ResourceUtils;
import org.opensubsystems.pattern.parameter.data.impl.ConfigurationImpl;
import org.xml.sax.SAXException;

/**
 * Class for accessing configuration parameters defined in XML format.
 * 
 * Note: At this time This class assumes that each parameter of configuration has 
 *       only a single value as constrained by data format definition in 
 *       ConfigurationRulesModule.
 * 
 * @author bastafidli
 */
public class XMLConfig extends OSSObject {
    // Constants ////////////////////////////////////////////////////////////////

    public static final String DEFAULT_CONFIGURATION_FILE = "ossconfig.xml";

    /**
     * File name of the configuration file to use to read the settings from.
     */
    private static String s_strConfigurationFileName;

    // Cached values ////////////////////////////////////////////////////////////

    /**
     * Commons logger variable used to log runtime information.
     */
    private static Logger s_logger = Log.getInstance(XMLConfig.class);

    // Constructors /////////////////////////////////////////////////////////////

    /** 
     * Private constructor since this class cannot be instantiated
     */
    private XMLConfig() {
        // Do nothing
    }

    // Logic ////////////////////////////////////////////////////////////////////

    public static String getConfigurationFileName() {
        return s_strConfigurationFileName;
    }

    public static void getConfigurationFileName(String strConfigurationFileName) {
        s_strConfigurationFileName = strConfigurationFileName;
    }

    /**
     * Read configuration from a previously configured file. If no file was 
     * configured then default location will be used.
     * 
     * @return ConfigurableObject 
     * @throws OSSConfigException - an error has occurred
     */
    public static ConfigurationImpl read() throws OSSConfigException {
        ConfigurationImpl configData = null;
        File configFile = null;
        URL configURL = null;

        try {
            if ((s_strConfigurationFileName != null) && (s_strConfigurationFileName.length() > 0)) {
                configFile = new File(s_strConfigurationFileName);
                if ((!configFile.exists()) || (configFile.isDirectory())) {
                    configFile = null;
                    configURL = FileUtils.findFileOnClassPath(DEFAULT_CONFIGURATION_FILE);
                    s_logger.log(Level.WARNING,
                            "Configuration file {0} doesn't exist"
                                    + " or is not a valid file, using default configuration" + " file "
                                    + DEFAULT_CONFIGURATION_FILE + " at {1}",
                            new Object[] { s_strConfigurationFileName, configURL });
                }
            } else {
                configURL = FileUtils.findFileOnClassPath(DEFAULT_CONFIGURATION_FILE);
                s_logger.log(Level.WARNING, "Configuration file is not specified," + " using default location "
                        + DEFAULT_CONFIGURATION_FILE + " at {0}", configURL);
            }
        } catch (IOException exc) {
            throw new OSSConfigException(exc);
        }

        if (configFile != null) {
            configData = read(configFile);
        } else if (configURL != null) {
            InputStream isConfigFile = null;

            try {
                isConfigFile = configURL.openStream();
                configData = read(isConfigFile);
            } catch (IOException exc) {
                throw new OSSConfigException("Error reading file " + configURL, exc);
            } finally {
                ResourceUtils.close(isConfigFile);
            }
        }

        return configData;
    }

    /**
     * Read configuration from a specified file
     * 
     * @param strfileConfig - file from which to read configuration
     * @return ConfigurableObject 
     * @throws OSSConfigException - an error has occurred
     */
    public static ConfigurationImpl read(String strfileConfig) throws OSSConfigException {
        return read(new File(strfileConfig));
    }

    /**
     * Read configuration from a specified file
     * 
     * @param fileConfig - file from which to read configuration
     * @return ConfigurableObject 
     * @throws OSSConfigException - an error has occurred
     */
    public static ConfigurationImpl read(File fileConfig) throws OSSConfigException {
        Digester digester = DigesterLoader.newLoader(new ConfigurationRulesModule()).newDigester();
        ConfigurationImpl config = null;

        try {
            config = digester.parse(fileConfig);
            s_logger.log(Level.FINE, "Read configuration {0}", config);
        } catch (IOException | SAXException exc) {
            throw new OSSConfigException("Error reading input file " + fileConfig.getName(), exc);
        }

        return config;
    }

    /**
     * Read configuration from a specified input stream
     * 
     * @param streamConfig - stream from which to read configuration
     * @return ConfigurableObject 
     * @throws OSSConfigException - an error has occurred
     */
    public static ConfigurationImpl read(InputStream streamConfig) throws OSSConfigException {
        Digester digester = DigesterLoader.newLoader(new ConfigurationRulesModule()).newDigester();
        ConfigurationImpl config = null;

        try {
            config = digester.parse(streamConfig);
            s_logger.log(Level.FINE, "Read configuration {0}", config);
        } catch (IOException | SAXException exc) {
            throw new OSSConfigException("Error reading input stream " + streamConfig.toString(), exc);
        }

        return config;
    }
}