/*
 * DataAccess.fx
 *
 * Created on Sep 27, 2007, 9:46:04 AM
 */

package tablesample;

/**
 * @author Radhika Gehant
 */
import javafx.ui.*;
import java.lang.Thread;
import java.lang.Exception;
import java.sql.*;

public class DatabaseAccess {
    
    private attribute driverName: String;
    private attribute jdbcUrl   : String;
    private attribute user      : String;
    private attribute password  : String;
    
    public attribute driver    : Driver;
    public attribute conn      : Connection;
    
    private attribute rs : ResultSet;
    private attribute stmt : Statement;
    
    public
    operation connect();
    public
    operation shutdown();
    
    public
    operation tableExists(table: String);
    public
    operation processDBQuery(qry: String): ResultSet;
    
}// Database

attribute DatabaseAccess.conn = null;
attribute DatabaseAccess.stmt = null;
attribute DatabaseAccess.rs = null;


operation DatabaseAccess.connect() {
    // Load driver class using context class loader    
    var thread      = Thread.currentThread();
    var classLoader = thread.getContextClassLoader();
    var driverClass = classLoader.loadClass(this.driverName);
    
    // Instantiate and register JDBC driver  
    this.driver = (Driver) driverClass.instantiate();
    // JavaFX Class
    DriverManager.registerDriver(driver);    
    // Connect to database    
    this.conn = DriverManager.getConnection(this.jdbcUrl, this.user, this.password);
}// Database.connect


operation  DatabaseAccess.processDBQuery(qry: String) :ResultSet {
    // process the query string
    try{
        if(null <> this.conn) {  
            if (this.stmt <> null) {
                this.stmt.close();
                this.stmt = null;
            }
            if (this.rs <> null) {
                this.rs.close();
                this.rs = null;
            }
            stmt = this.conn.createStatement();
            rs  =  stmt.executeQuery(qry);  
        }
    }    
    catch(e:SQLException) {
        e.printStackTrace();
    }           
    return rs;
}//processDB