You have a Java web application needing a relational SQL database. According to JavaEE conventions, you declare the DataSource in web.xml:
<resource-ref>
<res-ref-name>jdbc/DS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
and then fetch it in code with (DataSource)new InitialContext().lookup("java:comp/env/jdbc/DS").
Using Maven, Jetty and HSQLDB, you can very easily run the web application for local testing without having to setup neither a web container, nor a database. Add this to pom.xml:
<build>
<plugins>
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.0.5.v20130815</version>
<configuration>
<webApp>
<contextPath>/${project.name}</contextPath>
<jettyEnvXml>src/etc/jetty-ds.xml</jettyEnvXml>
</webApp>
</configuration>
<dependencies>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>2.3.1</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
And add a file src/etc/jetty-ds.xml to your project:
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://www.eclipse.org/jetty/configure_9_0.dtd">
<Configure id="wac" class="org.eclipse.jetty.webapp.WebAppContext">
<New id="DS" class="org.eclipse.jetty.plus.jndi.Resource">
<Arg><Ref id="wac"/></Arg>
<Arg>jdbc/DS</Arg>
<Arg>
<New class="org.hsqldb.jdbc.JDBCDataSource">
<Set name="DatabaseName">mem:db</Set>
<Set name="User">SA</Set>
<Set name="Password">""</Set>
</New>
</Arg>
</New>
</Configure>
Then run it locally with mvn jetty:run. The database will be in-memory and does not presist between runs. It is also possible to configure HSQLDB to persist data on disk, see documentation.
If you want to have access to in-memory database in your tests, add this dependency to pom.xml:
<dependencies>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>2.3.1</version>
<scope>test</scope>
</dependency>
</dependencies>
And create the DataSource in your test code like this:
import org.hsqldb.jdbc.JDBCDataSource;
JDBCDataSource hsqldbDs = new JDBCDataSource();
hsqldbDs.setDatabaseName("mem:.");
hsqldbDs.setUser("SA");
hsqldbDs.setPassword("");
Note: This will not add the DataSource to JNDI.