The simplest ActiveObjects database provider for the H2 database

For my current project i decided to use ActiveObjects as ORM layer. Additionally i looked for a free, java based database engine which offers support for

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Blobs and Clobs

Finally i decided to use the H2 database. Unfortunately i was lazy and didn’t check ActiveObjects list of supported databases.
ActiveObjects doesn’t support the H2 database out of the box.

Using ActiveObjects HSQLDatabaseProvider (H2 is known to be highly compatible with HSQL) doesn’t work because in ActiveObjects a DataBaseProvider has to return the appropriate JDBC driver class.
To use the HSQLDatabaseProvider for H2 anyway you can just extend it and overwrite the getDriverClass() method:

package net.java.ao.db;

import java.sql.Driver;

/**
 * @author netseeker
 *
 */
public class H2DatabaseProvider extends HSQLDatabaseProvider {

    /**
     * @param uri
     * @param username
     * @param password
     */
    public H2DatabaseProvider(String uri, String username, String password) {
	super(uri, username, password);
    }

    /*
     * (non-Javadoc)
     *
     * @see net.java.ao.db.HSQLDatabaseProvider#getDriverClass()
     */
    @SuppressWarnings("unchecked")
    @Override
    public Class< ? extends Driver> getDriverClass()
	    throws ClassNotFoundException {
	return (Class< ? extends Driver>) Class.forName("org.h2.Driver");
    }
}

The new DataBaseProvider can then be used like this:

    EntityManager manager = new EntityManager(new H2DatabaseProvider(
	    						dbProperties.getProperty("db.uri"),
	    						dbProperties.getProperty("db.username"),
	    						dbProperties.getProperty("db.password")));

3 Comments

Oktober 30, 2008 by netseeker in Development

3 Responses

Daniel Spiewak
Oktober 31, 2008 um 10:54 pm

You know, if H2 support is really that simple, I can move this functionality into the core distribution. That way you could still have auto-magical JDBC URI-based driver detection.

The one wrinkle is AO is into feature freeze for 1.0, which means that it still wouldn’t be “official” support for H2, but I don’t mind adding it to the list of supported databases and marking it as “experimental”.
netseeker
November 1, 2008 um 10:22 pm

Hi Daniel,
adding this basic H2-support to AO would be great – even if the support would be “experimental”. Thank you in advance.
I will try to contact Thomas Mueller who is the author of H2. I feel confident that he will help me to create a “real” DataBaseProvider for H2. Maybe that provider could then replace my simple hack in AO 1.x.
Thomas Mueller
November 3, 2008 um 10:43 pm

I had a look at the HSQLDatabaseProvider. There may be a few things that can be improved, but only minor items (renderOnUpdate maybe). I can help writing and testing a complete H2DatabaseProvider, but your initial implementation looks very good already! It would be great if this implementation could be included in AO 1.0 (even experimental)!

Regards,
Thomas