filebackup.java

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//
// This file is part of the OpenNMS(R) Application.
//
// OpenNMS(R) is Copyright (C) 2002-2003 The OpenNMS Group, Inc.  All rights reserved.
// OpenNMS(R) is a derivative work, containing both original code, included code and modified
// code that was published under the GNU General Public License. Copyrights for modified 
// and included code are below.
//
// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
//
// Copyright (C) 1999-2001 Oculan Corp.  All rights reserved.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// For more information contact:
//      OpenNMS Licensing       <[e-mail]>
//      http://www.opennms.org/
//      http://www.opennms.com/
//

package org.opennms.web.parsers;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Properties;

/**
 * This class makes a backup of an xml file. The backup should be made before
 * any new configuration xml is saved. The class will try to determine what
 * directory to backup to based on properties in the bluebird property file.
 * Failing this, a default will be used that is the current directory where the
 * call was made from. A default ".backup" extension will be placed on this
 * file.
 */
public class FileBackup {
    /**
     * The property string to look for in bluebird property file for the backup
     * directory
     */
    public static final String BACKUP_DIR_PROP = "org.opennms.bluebird.file.backupDir";

    /**
     * This method attempts to make a backup of an xml file. The first parameter
     * should be the full path to the original file at least relative to where
     * the method is running from, or the absolute path to the file. The second
     * parameter is the just the file name that will identify the backup. A
     * default extension will be added to this filename.
     * 
     * @param original
     *            a path and file name to the original file
     * @param fileName
     *            the name to give the backup
     * @throws XMLWriteException
     *             if the backup was not able to be made
     */
    public static void makeBackup(String original, String fileName) throws IOException {
        String backupDir = null;
        String backupExtension = ".backup";

        // see if we can find where the user wants to save this bad boy
        if (System.getProperty(BACKUP_DIR_PROP) == null) {
            Properties props = PropertyLoader.load(PropertyLoader.BLUEBIRD_PROP, PropertyLoader.LOCAL_ONLY);
            backupDir = props.getProperty(BACKUP_DIR_PROP);
        } else {
            backupDir = System.getProperty(BACKUP_DIR_PROP);
        }

        // all else fails save to whatever directory we are running from
        if (backupDir == null || backupDir.trim().equals("")) {
            backupDir = ".";
        }

        backupDir += System.getProperty("file.separator");

        // check to make sure the backup directory exists
        File backupFileDir = new File(backupDir);
        if (!backupFileDir.exists()) {
            backupFileDir.mkdirs();
        }

        // lets try to backup the file
        try {
            // I doubt that this is the best way to make a backup of a file,
            // but...

            // open up the original file
            BufferedReader originalBuffer = new BufferedReader(new FileReader(original));

            // open the backup file
            BufferedWriter backupBuffer = new BufferedWriter(new FileWriter(backupDir + fileName + backupExtension));

            // read each line from original, write it to backup
            String input;
            while ((input = originalBuffer.readLine()) != null) {
                backupBuffer.write(input);
                backupBuffer.newLine();
            }

            // close everything off
            originalBuffer.close();
            backupBuffer.flush();
            backupBuffer.close();
        } catch (Exception e) {
            throw new IOException("Error backing up " + fileName + " to " + backupDir + "\n" + e.getMessage());
        }
    }
}