We will connect with a database using a JDBC 4.0 driver. We will use Java DB as the example database. Java DB is Sun's version of the open-source Apache Derby database. Java DB is a lightweight (only 2MB), yet fully transactional, secure, and standards-based component. It also supports the SQL, JDBC, and Java EE standards. Java DB is a 100% Java technology database, and since Java is portable across platforms, Java DB can be run on any platform and its applications can be migrated to other open standard databases. Java DB is packaged with JDK 6. Therefore, all that is required to install Java DB is to install JDK 6. We connect with Java DB database using the JDBC 4.0 driver. Create a Java application, JDBCConnection.java, in a directory, C:/JavaDB, and add the directory to the CLASSPATH system environment variable. Java DB can be started in the embedded mode or as network server. Embedded mode is used to connect to the Java DB from a Java application running in the same JVM as the Java DB database. Java DB as a network server is used to connect with the database from different JVMs across the network. We will start Java DB in embedded mode from the JDBCConnection.java application. We will load the JDBC 4.0 driver automatically using the Java SE Service Provider mechanism. For automatic loading of the JDBC driver, we need to add the Java DB JDBC 4.0 driver JAR file, C:/Program Files/Sun/JavaDB/lib/derby.jar to the CLASSPATH variable. Java DB provides a batch script, setEmbeddedCP.bat in the bin directory to set the CLASSPATH for the embedded mode. Run the setEmbeddedCP script from the directory from which the JDBCConnection.java application is to be run as follows:

"C:\Program Files\Sun\JavaDB\bin\setEmbeddedCP.bat"

JAR file, derby.jar is added to the CLASSPATH. The derby.jar file includes a directory structure, META-INF/services/, and a file, java.sql.Driver, in the services directory. The java.sql.Driver file specifies the following JDBC driver class for the Java DB that is to be loaded automatically using the Java SE Service Provider mechanism:

org.apache.derby.jdbc.AutoloadedDriver

In the JDBCConnection.java application, specify the connection URL for the Java DB database. Create a new database instance by specifying the database name, demodb, and the create attribute as, true:

String url="jdbc:derby:demodb;create=true";

Connect with the Java DB database using the getConnection() method of the DriverManager class:

Connection conn = DriverManager.getConnection(url);

The DriverManager automatically loads the JDBC 4.0 driver class, org.apache.derby.jdbc.AutoloadedDriver, which is specified in the java.sql.Driver file using the Java SE Service Provider mechanism. The JDBC driver is not required to be loaded using the Class.forName() method using a JDBC 3.0 driver. The JDBCConnection.java application is listed below:

import java.sql.*;
public class JDBCConnection
{
public void connectToDatabase()
{
try
{
String url="jdbc:derby:demodb;create=true";
Connection conn = DriverManager.getConnection(url);
System.out.println("Connection Established");
}
catch (SQLException e)
{
System.out.println(e.getMessage());
}
}
public static void main(String[] argv)
{
JDBCConnection jdbc = new JDBCConnection();
jdbc.connectToDatabase();
}
}

Other Relational Database Management Systems (RDBMS) databases provide a JDBC 4.0 driver that can be connected using the JDBC 4.0 driver, as discussed for the Java DB database. The connection URLs, and JDBC 4.0 drivers for some of the commonly used databases are discussed in following table: