Java JDBC Reds Connection checkConnection()

Description

Checks if connection is supposed to be present and attempts to reconnect if there was previously an error.

License

Open Source License

Return

true if the connection is established upon return

Declaration

private static boolean checkConnection() throws SQLException 

Method Source Code

//package com.java2s;
/**//from   w w w . j  a va2s .c  o  m
 * Java Settlers - An online multiplayer version of the game Settlers of Catan
 * Copyright (C) 2003  Robert S. Thomas
 * Portions of this file Copyright (C) 2009-2010,2012 Jeremy D Monin <jeremy@nand.net>
 *
 * 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 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * The author of this program can be reached at thomas@infolab.northwestern.edu
 **/

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

import java.sql.SQLException;

public class Main {
    private static Connection connection = null;
    /**
     * Retain the URL (default, or passed via props to {@link #initialize(String, String, Properties)}).
     * @since 1.1.09
     */
    private static String dbURL = null;
    /**
     * This flag indicates that the connection should be valid, yet the last
     * operation failed. Methods will attempt to reconnect prior to their
     * operation if this is set.
     */
    private static boolean errorCondition = false;
    /** Cached username used when reconnecting on error */
    private static String userName;
    /** Cached password used when reconnecting on error */
    private static String password;
    private static String CREATE_ACCOUNT_COMMAND = "INSERT INTO users VALUES (?,?,?,?,?);";
    private static String RECORD_LOGIN_COMMAND = "INSERT INTO logins VALUES (?,?,?);";
    private static String USER_PASSWORD_QUERY = "SELECT password FROM users WHERE ( users.nickname = ? );";
    private static String HOST_QUERY = "SELECT nickname FROM users WHERE ( users.host = ? );";
    private static String LASTLOGIN_UPDATE = "UPDATE users SET lastlogin = ?  WHERE nickname = ? ;";
    private static String SAVE_GAME_COMMAND = "INSERT INTO games VALUES (?,?,?,?,?,?,?,?,?,?);";
    private static String ROBOT_PARAMS_QUERY = "SELECT * FROM robotparams WHERE robotname = ?;";
    private static PreparedStatement createAccountCommand = null;
    private static PreparedStatement recordLoginCommand = null;
    private static PreparedStatement userPasswordQuery = null;
    private static PreparedStatement hostQuery = null;
    private static PreparedStatement lastloginUpdate = null;
    private static PreparedStatement saveGameCommand = null;
    private static PreparedStatement robotParamsQuery = null;

    /**
     * Checks if connection is supposed to be present and attempts to reconnect
     * if there was previously an error.  Reconnecting closes the current
     * conection, opens a new one, and re-initializes the prepared statements.
     *
     * @return true if the connection is established upon return
     */
    private static boolean checkConnection() throws SQLException {
        if (connection != null) {
            return (!errorCondition) || connect(userName, password);
        }

        return false;
    }

    /**
     * initialize and checkConnection use this to get ready.
     */
    private static boolean connect(String user, String pswd)
            throws SQLException {
        connection = DriverManager.getConnection(dbURL, user, pswd);

        errorCondition = false;
        userName = user;
        password = pswd;

        // prepare PreparedStatements for queries
        createAccountCommand = connection
                .prepareStatement(CREATE_ACCOUNT_COMMAND);
        recordLoginCommand = connection
                .prepareStatement(RECORD_LOGIN_COMMAND);
        userPasswordQuery = connection
                .prepareStatement(USER_PASSWORD_QUERY);
        hostQuery = connection.prepareStatement(HOST_QUERY);
        lastloginUpdate = connection.prepareStatement(LASTLOGIN_UPDATE);
        saveGameCommand = connection.prepareStatement(SAVE_GAME_COMMAND);
        robotParamsQuery = connection.prepareStatement(ROBOT_PARAMS_QUERY);

        return true;
    }
}

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