7.1 Connecting to MySQL Using the JDBC DriverManager Interface

When you are using JDBC outside of an application server, the DriverManager class manages the establishment of connections.

Specify to the DriverManager which JDBC drivers to try to make Connections with. The easiest way to do this is to use Class.forName() on the class that implements the java.sql.Driver interface. With MySQL Connector/J, the name of this class is com.mysql.cj.jdbc.Driver. With this method, you could use an external configuration file to supply the driver class name and driver parameters to use when connecting to a database.

The following section of Java code shows how you might register MySQL Connector/J from the main() method of your application. If testing this code, first read the installation section at Chapter 4, Connector/J Installation, to make sure you have connector installed correctly and the CLASSPATH set up. Also, ensure that MySQL is configured to accept external TCP/IP connections.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

// Notice, do not import com.mysql.cj.jdbc.*
// or you will have problems!

public class LoadDriver {
    public static void main(String[] args) {
        try {
            // The newInstance() call is a work around for some
            // broken Java implementations

            Class.forName("com.mysql.cj.jdbc.Driver").newInstance();
        } catch (Exception ex) {
            // handle the error
        }
    }
}

After the driver has been registered with the DriverManager, you can obtain a Connection instance that is connected to a particular database by calling DriverManager.getConnection():

Example 7.1 Connector/J: Obtaining a connection from the DriverManager

If you have not already done so, please review the portion of Section 7.1, “Connecting to MySQL Using the JDBC DriverManager Interface” above before working with the example below.

This example shows how you can obtain a Connection instance from the DriverManager. There are a few different signatures for the getConnection() method. Consult the API documentation that comes with your JDK for more specific information on how to use them.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

Connection conn = null;
...
try {
    conn =
       DriverManager.getConnection("jdbc:mysql://localhost/test?" +
                                   "user=minty&password=greatsqldb");

    // Do something with the Connection

   ...
} catch (SQLException ex) {
    // handle any errors
    System.out.println("SQLException: " + ex.getMessage());
    System.out.println("SQLState: " + ex.getSQLState());
    System.out.println("VendorError: " + ex.getErrorCode());
}

Once a Connection is established, it can be used to create Statement and PreparedStatement objects, as well as retrieve metadata about the database. This is explained in the following sections.

When the user for the connection is unspecified, Connector/J's implementations of the authentication plugins use by default the name of the OS user who runs the application for authentication with the MySQL server (except when the Kerberos authentication plugin is being used; see Section 6.12.2, “Connecting Using Kerberos” for details).

Note

A user name is considered unspecified only when the following conditions are all met:

1. The method DriverManager.getConnection(String url, String user, String password) is not used.

2. The connection property user is not used in, for example, the connection URL,or elsewhere.

3. The user is not mentioned in the authority of the connection URL, as in jdbc:mysql://localhost:3306/test, or jdbc:mysql://@localhost:3306/test.

Notice if (1) or (2) is not true and an empty string is passed, the user name is an empty string then, and is not considered unspecified.