Spring JDBC and Connection Object - spring

Question

I'm building an app using a proprietary api. To connect to the database I use a method that returns a Connection object and then on that connection I call the appropriate methods to run queries on the database for example....
Connection conn = JdbcServiceFactory.getInstance().getDefaultDatabase().getConnectionManager().getConnection();
PreparedStatement ps = conn.prepareStatement("select * from test");
If I'm choosing to use Spring MVC 3 for my next project, what must I do to get the database connection setup? From what I've seen in the documentation, I have use the datasource tag in the container and pass a URL, username, and password. As shown, I currently don't have to do that to get the connection.

Answer 1

At the end of the day your proprietary API must access some database (available on some server), using some credentials. You just don't see this. In Spring you must first define some DataSource. Either use existing librariess like dbcp, bonecp or c3p0 or take one provided by your application server via jndi. As long as they implement DataSource interface, it doesn't matter what approach you choose. Too much to explain each one in detail.
Once you have DataSource bean set up, I strongly recommend using JdbcTemplate which simplifies your JDBC code a lot, e.g:
List<Map<String,Object>> res = jdbcTemplate.queryForList("select * from test");
...and much more.
UPDATE: If you want to use your existing legacy API with modern frameworks expecting DataSource (pretty much all of them), implementing DataSource adapter is trivial (remaining methods can stay unimplemented, throwing UnsupportedOperationException):
public class LegacyDataSourceAdapter implements DataSource {
#Override
public Connection getConnection() throws SQLException {
return JdbcServiceFactory.getInstance().getDefaultDatabase().getConnectionManager().getConnection();
}
#Override
public Connection getConnection(String username, String password) throws SQLException {
return getConnection();
}
//other methods are irrelevant
}
Now just create an instance of LegacyDataSourceAdapter (maybe as a Spring bean) and pass it to JdbcTemplate, Hibernate, myBatis...
BTW you have here some first class example of bad API design:
Connection conn = JdbcServiceFactory.
getInstance().
getDefaultDatabase().
getConnectionManager().
getConnection();