Java Tips - Connecting to a JDBC Database

The static method DriverManager.getConnection( ) lets you connect to the database using a URL-like syntax for the database name (for example, jdbc:dbmsnetproto://server:4567/mydatabase) and a login name and password. The "dbURL" that you give must begin with jdbc:. The rest of it can be in whatever form the driver vendor's documentation requires and is checked by the driver. The DriverManager asks each driver you have loaded (if you've loaded any) to see if it can handle a URL of the form you provided. The first one that responds in the affirmative gets to handle the connection, and its connect( ) method is called for you (by DriverManager.getConnection( )).

Four types of drivers are defined by Sun (not in the JDBC specification but in their less formal documentation)

1. JDBC-ODBC bridge = Provide JDBC API Access.
2. Java and Native Driver = Java code calls Native DB driver.
3. Java and Middleware = Java contacts Middleware Server.
4. Pure Java = java contacts (possibly remote) DB directly.

Example: Connect.java

import java.awt.*;

import java.sql.*;



/** Load a driver and connect to a database.

 */

public class Connect {



    public static void main(String[] av) {

        String dbURL = "jdbc:odbc:Companies";

        try {

            // Load the jdbc-odbc bridge driver

            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");



            // Enable logging

            DriverManager.setLogStream(System.err);



            System.out.println("Getting Connection");

            Connection conn = 

                DriverManager.getConnection(dbURL, "ian", "");    // user, passwd



            // If a SQLWarning object is available, print its

            // warning(s).  There may be multiple warnings chained.



            SQLWarning warn = conn.getWarnings( );

            while (warn != null) {

                System.out.println("SQLState: " + warn.getSQLState( ));

                System.out.println("Message:  " + warn.getMessage( ));

                System.out.println("Vendor:   " + warn.getErrorCode( ));

                System.out.println("");

                warn = warn.getNextWarning( );

            }



            // Process the connection here...



            conn.close( );    // All done with that DB connection



        } catch (ClassNotFoundException e) {

            System.out.println("Can't load driver " + e);

        } catch (SQLException e) {

            System.out.println("Database access failed " + e);

        }

    }

}