dbtools.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.
//
// Modifications:
//
// 2003 May 1: Added code to support JDBC poller.
//
// Original code base 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.netmgt;

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * This class is intended to be group some utility classes related with RDBMS
 * and the capsd and monitoring plugins.
 * 
 * @author Jose Vicente Nunez Zuleta ([e-mail]) - RHCE,
 *         SJCD, SJCP
 * @version 0.1 - 07/22/2002
 * @since 0.1
 */
public class DBTools {

    private static int _counter;

    private static DBTools _instance;

    /**
     * The JDBC hostname. This token is replaced when the url is constructed.
     * 
     * @see #constructUrl
     */
    public static final String JDBC_HOST = "OPENNMS_JDBC_HOSTNAME";

    /**
     * Minimal port range
     */
    public static int MIN_PORT_VALUE = 1024;

    /**
     * Maximun port range
     */
    public static int MAX_PORT_VALUE = 65535;

    /**
     * Default Sybase JDBC driver to use. Defults to
     * 'com.sybase.jdbc2.jdbc.SybDriver'
     */
    public static final String DEFAULT_JDBC_DRIVER = "com.sybase.jdbc2.jdbc.SybDriver";

    /**
     * Default user to use when connecting to the database. Defaults to 'sa'
     */
    public static final String DEFAULT_DATABASE_USER = "sa";

    /**
     * Default port to use to check this service. Defaults to '4100' Make sure
     * than is less than MAX_PORT_VALUE and greather than MIN_PORT_VALUE
     * 
     * @see #MIN_PORT_VALUE
     * @see #MAX_PORT_VALUE
     */
    public static final int DEFAULT_PORT = 4100;

    /**
     * Default database password. Should be empty. You should not put a database
     * password here (or event worst, harcode it in the code) Instead call the
     * class method that accepts a map
     */
    public static final String DEFAULT_DATABASE_PASSWORD = "";

    /**
     * Default vendor protocol, like jdbc:sybase:Tds:
     */
    public static final String DEFAULT_URL = "jdbc:sybase:Tds:" + JDBC_HOST + "/tempdb";

    // Pattern for the JDBC_HOST
    private static final Pattern _pattern = Pattern.compile(JDBC_HOST);

    /**
     * Hide the constructor, this class follows the "Singleton" pattern.
     */
    private DBTools() {
        // do nothing
    }

    /**
     * Returns a single instance of this class to the caller. We do not want
     * multplie copies of this class loaded, just one.
     * 
     * @return DBTools A class instance
     */
    public synchronized static DBTools getInstance() {
        if (_instance == null) {
            _instance = new DBTools();
        }
        _counter++;
        return _instance;
    }

    /**
     * Return how many instances of this objects are loaded now
     * 
     * @return int Nnumber of instances on this JVM
     */
    public int getNumberOfInstances() {
        return _counter;
    };

    /**
     * Constructs a JDBC url given a set of fragments. The resulting Url will
     * have the form: <br>
     * <code>jdbc:<protocol:<b>hostname</b>:<b>4100</b></code>
     * 
     * @param hostname_
     *            The hostname where the database server is
     * @param url_
     *            (for example jdbc:sybase:Tds:@{link #JDBC_HOST
     *            JDBC_HOST}:4100/tempdb). The JDBC_HOST is replaced by the real
     *            hostname
     * @throws NullPointerException
     *             If one of the arguments is null
     * @throws IllegalArgumentException
     *             If the JDBC_HOST is not part of the JDBC url
     */
    public static String constructUrl(String url_, String hostname_) throws IllegalArgumentException, NullPointerException {
        String url = null;

        if (url_ == null) {
            throw new NullPointerException(DBTools.class.getName() + ": url cannot be null");
        }
        if (hostname_ == null) {
            throw new NullPointerException(DBTools.class.getName() + ": hostname cannot be null");
        }
        try {
            Matcher match = _pattern.matcher(url_);
            url = match.replaceFirst(hostname_);
        } catch (PatternSyntaxException patternExp) {
            throw patternExp;
        }
        return url;
    }

} // End of class