How to manage database settings from within a Spring MVC web application?

Question

I have been working with Spring Framework 3.0 for the last couple weeks and have been really impressed. This is my first project with Java. My main problem is that I can't find a way to let the end user manage their own database connection from within the web application. The project I am working on will be installed on the client's computer and they will provide all the connection information. At this point whenever the DataSource is unavailable I get an error I am not sure how to handle:

java.sql.SQLException: Network error IOException: Connection refused

I tried to lazy load the dataSource in the xml configuration, however it was still loaded when application started during the Pre-instantiating singletons phase.

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"     
    lazy-init="true">    
    <property name="driverClassName" value="${jdbc.driver}" />
    <property name="url"
      value="${jdbc.urlprefix}://${jdbc.server}:${jdbc.port}/${jdbc.database}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
    <property name="initialSize" value="2" />
    <property name="maxActive" value="5" />
</bean>

<bean id="sessionFactory"
    class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"
    lazy-init="true">
    <property name="dataSource" ref="dataSource" />
    <property name="hibernateProperties">
      <props>
        <prop key="hibernate.dialect">${hibernate.dialect}</prop>
        <prop key="hibernate.show_sql">false</prop>
      </props>
    </property>
    <property name="annotatedClasses">
      <list>
           ....
      </list>
    </property>
</bean>

<bean id="transactionManager"
    class="org.springframework.orm.hibernate3.HibernateTransactionManager"
    lazy-init="true">
    <property name="sessionFactory" ref="sessionFactory" />
</bean>

I am hoping when the database is unavailable or not configured correctly I could just redirect the user to a page not dependent on the database connection so the settings can be managed. I am just not sure how accomplish this when the IoC container is expecting the DataSource to be configured correctly from the start.

Thank you in advance!

Answer 1

this IS a hack.... use an in memory database as a default configuration.

if when the system comes up, it is still the default database, then you know an error ocurred.

Answer 2

Spring's AbstractRoutingDataSource is an intermediary DataSource that routes getConnection() calls to another target DataSource determined an run-time. Set the default target data source to an in-memory database so there is a database to connect to when the application context is loaded. When the user provides the connection information, your AbstractRoutingDataSource subclass can route to another DataSource configured with the connection information.