In Tomcat's server.xml file add this just before  the </Host> tag

<!-- Dwight added the context for JDBC configuration-->
<Context path="/appName" docBase="appName">
    <Resource name="jdbc/appName" scope="Shareable" type="javax.sql.DataSource"/>
    <ResourceParams name="jdbc/appName">
        <parameter>
            <name>factory</name>
          <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
        </parameter>

        <!-- DBCP database connection settings -->
        <parameter>
            <name>url</name>
            <value>jdbc:mysql://localhost/appName</value>
        </parameter>
        <parameter>
         <name>driverClassName</name><value>com.mysql.jdbc.Driver</value>
        </parameter>
        <parameter>
            <name>username</name>
            <value>yourUserNameHere</value>
        </parameter>
        <parameter>
            <name>password</name>
            <value>yourPasswordHere</value>
        </parameter>

        <!-- DBCP connection pooling options -->
        <parameter>
            <name>maxWait</name>
            <value>3000</value>
        </parameter>
        <parameter>
            <name>maxIdle</name>
            <value>100</value>
        </parameter>
        <parameter>
            <name>maxActive</name>
            <value>10</value>
        </parameter>
    </ResourceParams>
</Context>