Injecting A DataSource Into A Factory

[Jason Ferguson]

I am attempting to inject a DataSource into a factory class I wrote. This factory was SUPPOSED to have static methods that would take a String specifying SQL, and return a ResultSet from the SQL. This way I can call the code from a scriptlet in a JSP?

The big question will be "WHY would any sane person want to do this?" The answer is that this is an existing application that I have to fix, but am not allowed to rewrite from scratch using DAOs (*grumble*). So, I wanted to replace a bunch of ugly JDBC code in the scriptlet with something that looks like this:

ResultSet rs = ResultSetFactory.getResultSet(sql);

However, Spring can't inject the datasource into a static variable (declared as "private static DataSource dataSource". If anyone has any ideas, I would LOVE to hear them. I don't want to have to instantiate the ResultSetFactory, because that seems to miss the point of a Factory class.

Here is my non-working code:

public class ResultSetFactory {
 
    private static DataSource dataSource;
 
    public static void setDataSource(DataSource ds) {
        dataSource = ds;
    }
 
    public static ResultSet getResultSet(String sql) throws SQLException {
 
        Connection conn = dataSource.getConnection();
        PreparedStatement pstmt = conn.prepareStatement(sql);
 
        ResultSet results = pstmt.executeQuery();
 
        pstmt.close();
        conn.close();
        return results;
    }
}

And here is my applicationContext.xml:

<!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN" "http://www.springframework.org/dtd/spring-beans.dtd">
 
<beans>
    <bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
        <property name="resourceRef">
            <value>true</value>
        </property>        
        <property name="jndiName">
            <value>java:/comp/env/jdbc/uniCBTDataSource</value>
        </property>
    </bean>
</beans>

Again, any ideas are appreciated.

[Herman Schelti]

hi,

you can make the method getResultSet static, but that does not mean that setDatasource and it's property have to be.

Apart from that: I don't think your code will work, if you close the connection I don't think you can access the resultset anymore.

Herman

[Jason Ferguson]

Yes, I now notice this in the ResultSet javadocs... thwarted again. This explains the ugly NullPointerExceptions that I noticed 10 minutes before leaving for the day yesterday.

Originally posted by Herman Scheltinga:
hi,

you can make the method getResultSet static, but that does not mean that setDatasource and it's property have to be.

Apart from that: I don't think your code will work, if you close the connection I don't think you can access the resultset anymore.

Herman