"Yaldiz, Sunay" wrote:
>
> Hello all,
>
> I have a question about XML mapping.
> I have a class which looks like this:
>
> public class GlobalEnvironment{
> public double accelerationOfGravity ;
> public double densityWater ;
> public double densityAir ;
> public double viscosityWater;
> public double temperatureWater;
> public double salinityWater ;
>
> }
>
> I want the XML structure for GlobalEnvironment instances as follows:
>
> <GlobalEnvironment>
> <Water>
> <Viscosity>34</Viscosity>
> <Density>1.0</Density>
> <Temperature>100</Temperature>
> <Salinity>34</Salinity>
> </Water>
> <Gravity>10.0</Gravity>
> <Air>
> <Density>0.00123</Density>
> </Air>
> </GlobalEnvironment>
>
> I mean I want that the fields ...Water in the class are residing under
> element <Water>, and respectively for air.
> Of course it is possible to create this XML structure by changing the
> class definition a little bit, but what I want is not this. Is it
> possible to map this class definition to such an XML structure? Or is it
> must for me either to change the XML representation of the
> GlobalEnvironment class or change the GlobalEnvironment and add some
> classes Water, Air ...?
>
> I tried using location attribute setting location="Water" for mapping of
> fields densityWater,viscosityWater,temperatureWater and salinityWater
> but it did not give the result I wanted. The mapping packed the fields
> in different "Water" elements.
This is a known issue with the location attribute, which I am working
on.
Another solution is to use some Wrapper classes. You don't have to
change your existing model at all, you can keep using your existing
model, but a few Wrapper classes (Air, Water) that are returned by
special field handlers would give you the result you're looking for.
For example:
public class Air {
private double density;
/**
* Default constructor (required by Castor)
*/
public Air() {
super();
}
/**
* A Convenience constructor that initializes
* this Air instance with the given GlobalEnvironment
*/
public Air(GlobalEnvironment ge) {
density = ge.densityAir;
}
public double getDensity() {
return density;
}
public void setDensity(double density) {
this.density = density;
}
}
Then you could use a custom org.exolab.castor.mapping.FieldHandler (see
also AbstractFieldHandler or GeneralizedFieldHandler), whose getValue
would return
the proper Air, or Water wrapper class, and the setValue would do the
reverse:
public class AirFieldHandler extends AbstractFieldHandler {
...
public Object getValue(Object target) {
return new Air((GlobalEnvironment)target);
}
...
public void setValue(Object target, Object value) {
GlobalEnvironment ge = (GlobalEnvironment)target;
Air air = (Air)value;
ge.densityAir = air.getDensity();
}
}
Your mapping file would then look like:
<class name="com.amce.GlobalEnvironment">
<field name="air" type="com.acme.Air"
handler="com.acme.AirFieldHandler"/>
<field name="air" type="com.acme.Water"
handler="com.acme.WaterFieldHandler"/>
</class>
So you don't have to change your GlobalEnvironment class to get the
desired result, but it is a bit more work. Hopefully I'll have the
location attribute code will be cleaned up soon.
Hope that helps,
--Keith
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