XStream different alias for same class (Map.class) for different fields - xml-serialization

Question

I am using XStream to convert a Java class which has fields of the type java.util.Map. I have a converter for java.util.Map which displays the key of the Map as an xml element and the value of the map as the value for the xml element. I have registered the converter using registerConverter method. When I perform the marshalling, I get the following output.
<cart account_id="123" shift_id="456" account_postings_id="641">
<supervisor_id>555</supervisor_id>
<payments>
<map sequence="1">
<amount>123.45</amount>
<billing_method>12345</billing_method>
<form>card</form>
<delivery_mode>Q</delivery_mode>
</map>
<map sequence="2">
<amount>123.45</amount>
<person_id>2333</person_id>
<form>cash</form>
<delivery_mode>Q</delivery_mode>
</map>
</payments>
<items>
<map sequence="3">
<amount>1.00</amount>
<type>pay_toll</type>
<toll_id>1234</toll_id>
</map>
</items>
</cart>
Instead of the map tags appearing, I would want to use different tags based on the field name in the class. For example, the Payments list will have tag name payment and the Items list will have a tag name item for each Map element.
How do we dynamically set alias based on field in the same class?
-Anand

Answer 1

I used XStream to create atom feed reports. Entries in the contents can be of different object classes and I wanted to use the class name dynamically. Here is my solution. I created a ObjectContentConverter and passed the XStream on, and then use xstream.aliasField() with getClass().getSimpleName().
private class ObjectContentConverter implements Converter {
XStream xStream;
private ObjectContentConverter(XStream xStream) {
this.xStream = xStream;
}
#Override
public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
String className = WordUtils.uncapitalize(source.getClass().getSimpleName());
xStream.aliasField(className, Content.class, "objectContent");
xStream.marshal(source, writer);
}
#Override
public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
return null; //To change body of implemented methods use File | Settings | File Templates.
}
#Override
public boolean canConvert(Class type) {
return true; //To change body of implemented methods use File | Settings | File Templates.
}
}
xStream.registerLocalConverter(Content.class, "objectContent", new ObjectContentConverter(xStream));