Rule Definition
Creating a connection to the database server is expensive. It is even more expensive if the server is located on another machine. Connection can take 30 to 50 ms depending on the platform.

Remediation
Use a pool of connections unless the DriverManager is the implementation of the connection pool itself. In a J2EE container, it is recommended to use a JNDI DataSource provided by the container. Outside of a J2EE container, consider Apache's Jakarta Commons DBCP or C3P0. Commons DBCP's BasicDataSource and C3P0's ComboPooledDataSource are full connection pool beans, supporting the same basic properties as this class plus specific settings (such as minimal/maximal pool size etc)..

Violation Code Sample

Connection con = DriverManager.getConnection(URL, user, password); // VIOLATION

Fixed Code Sample

import org.apache.commons.dbcp.BasicDataSource;

BasicDataSource ds = new BasicDataSource();
ds.setDriverClassName("oracle.jdbc.driver.OracleDriver");
ds.setUsername("scott");
ds.setPassword("tiger");
ds.setUrl("jdbc:oracle:thin:scott/tiger@myhost:1521:mysid");
Connection con = ds.getConnection();

http://www.precisejava.com/javaperf/j2ee/EJB.htm#EJB142 http://www.webdevelopersjournal.com/columns/connection_pool.html http://commons.apache.org/dbcp/ http://sourceforge.net/projects/c3p0