Referencing a datasource from a Java Component - components

Question

I have a datasource as a global element, is it possible to reference it from a Java Component. Im using Mule 3.4 version

Answer 1

If you can I would use setter injection:
<component>
<singleton-object class="SomeJavaComponent">
<property key="dataSource" value-ref="jdbcDataSource"/>
</singleton-object>
</component>
with a setter defined in your component similar to the following:
private DataSource dataSource;
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource
}
Alternatively, not the nicest way, but you can get it from the registry:
this.muleContext.getRegistry.lookupObject("jdbcDataSource");

Answer 2

Well in reality that's not the correct answer. There is no such animal as DataSource.
Here is a working (tested) example, Mule 3.5, standalone Mule CE 3.4.1:
<component doc:name="callDynamicQuery">
<singleton-object class="org.fiuze.trasnsformers.DynamicSql">
<property key="dataSource" value="null" value-ref="MySqlDataConnector"/>
</singleton-object>
</component>
Note, that the MySqlDataConnector is a jdbc:mysql-data-source (jdbc-ee:mysql-data-source) and NOT the jdbc:connector (jdbc-ee:connector).
The java class is like this:
package org.fiuze.trasnsformers;
import java.sql.SQLException;
import org.enhydra.jdbc.standard.StandardDataSource;
import java.sql.Connection;
public class DynamicSql {
private StandardDataSource dataSource;
public StandardDataSource getConn() {
return dataSource;
}
public void setConn(StandardDataSource conn) {
this.dataSource = conn;
}
public void callSql(String sql) throws SQLException {
Connection connection = this.dataSource.getConnection();
try {
connection.prepareStatement(sql).execute();
} catch (SQLException sqlE) {
connection.close();
throw new SQLException(sqlE);
} finally {
connection.close();
}
}
}
This example will work as long as your example has a working dataSource.
When I tried the above answer, Mule didn't initialize the property since there was no fitting class.
I am expanding on the above answer in the light of my deploying this to production. The autowire functionality in Studio CE didn't seem to pick up the Data Source.
Instead of letting you down and letting you spend hours like myself, here is your solution:
package org.fiuze.trasnsformers;
import java.sql.SQLException;
import org.enhydra.jdbc.standard.StandardDataSource;
import org.mule.api.MuleContext;
import org.mule.api.annotations.expressions.Lookup;
import org.mule.api.context.MuleContextAware;
import java.sql.Connection;
public class DynamicSql implements MuleContextAware {
#Lookup
private MuleContext muleContext;
private StandardDataSource dataSource;
public StandardDataSource getConn() {
return dataSource;
}
public void setConn(StandardDataSource conn) {
this.dataSource = conn;
}
public void callSql(String sql) throws SQLException {
if (this.dataSource == null) {
this.dataSource = this.muleContext.getRegistry().lookupObject("MySqlDataConnector");
}
Connection connection = this.dataSource.getConnection();
try {
connection.prepareStatement(sql).execute();
} catch (SQLException sqlE) {
connection.close();
throw new SQLException(sqlE);
} finally {
connection.close();
}
}
#Override
public void setMuleContext(MuleContext context) {
this.muleContext = context;
}
}
The main idea there is that we can use the MuleContext and grab it from there. See the elegant way of pulling the context by a simple annotation. This deployed and worked.
Finally, you could simplify now the code. If you have EE, you probably don't need to load in the context and your DynamicSql class will be lightweight. If you count your coins, and running on CE, you can still do it.
With a little sweat.