Keith,
Thanks for the response. I tried returning null from my newInstance
methods. This time I get an error "Unable to create a new instance of type
: Subjects"... Subjects is an enum type and has no constructor.
Do we need to specify anything else in my mapping?
Is there any place where I could find some documentation about writing
custom handlers, for a better understanding.
Thanks
Ram
|---------+---------------------------->
| | Keith Visco |
| | <[EMAIL PROTECTED]|
| | om> |
| | |
| | 01/18/2005 03:35 |
| | PM |
| | Please respond to|
| | castor-dev |
| | |
|---------+---------------------------->
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|
|
| To: castor-dev@exolab.org
|
| cc:
|
| Subject: Re: [castor-dev] Re: TypeSafe Enums and Collections
|
>--------------------------------------------------------------------------------------------------------------------------------------------------|
You're on the right track, but you should probably return null from the
newInstance methods instead of throwing exceptions. Castor will invoke
those methods and will expect either an actual instance or null as the
return value.
Also if you extend GeneralizedFieldHandler instead of
AbstractFieldHandler your code will be a lot cleaner and smaller because
you don't need to figure out the setter/getter methods as it's already
done for you.
I know it's a limitation that the GeneralizedFieldHandler doesn't have
built-in support to iterate automatically over collections, so everyone
has to write their own collection support inside the convert methods.
That's something I'm working on. In the meantime, your custom handler
should work with a little tweaking.
--Keith
[EMAIL PROTECTED] wrote:
> hey,
>
> Just wondering if anyone had any thought on this. I had to write up a
> custom handler (code borrowed from an earlier post and make changes for
> handling a list). The marshalling works but the unmarshalling tries to
> create an instance and fails
> for the type safe enums. This is kindof urgent and wanted to find out if
> anyone has gotten this to work and if so how.
>
> public class HmsiEnumTypeFieldHandler extends AbstractFieldHandler {
>
> /**
> * Returns the value of the field from the object. The object should
> have a
> * method named <code>"get" +
> getFieldDescriptor().getFieldName()</code>.
> * <br>
> * <b>Example </b>: Field name =<code>identification</code>, method
> * name =<code>getIdentification()</code>. This getter should return
> the
> * <i>typesafe enum </i> static instance.
> *
> * @param o
> * The object
> * @return The value of the field
> * @throws IllegalStateException
> * The Java object has changed and is no longer supported
> by
> * this handler, or the handler is not compatible with
the
> Java
> * object
> */
> public Object getValue(final Object o) throws IllegalStateException {
> final FieldDescriptor fd = getFieldDescriptor();
> final String name = fd.getFieldName();
> final String methodName = "get".concat(
> name.substring(0, 1).toUpperCase()).concat(
> name.substring(1, name.length()));
>
> try {
> final Method method = o.getClass().getMethod(methodName,
> new Class[] {});
>
> // make sure we handle arrays of enums
> Object result = method.invoke(o, new Object[] {});
>
> if (result == null) {
> return result;
> }
>
> if (result.getClass().isArray()) {
> int size = Array.getLength(result);
> String[] values = new String[size];
>
> for (int i = 0; i < size; i++) {
> values[i] = Array.get(result, i).toString();
> }
>
> result = values;
> }
> return result;
> } catch (NoSuchMethodException e) {
> e.printStackTrace();
> throw new IllegalStateException("Class " + o.getClass()
> + " must have method " + methodName);
> } catch (IllegalAccessException e) {
> e.printStackTrace();
> throw new IllegalStateException("Method " + methodName
> + " from class " + o.getClass() + " must be public");
> } catch (InvocationTargetException e) {
> e.printStackTrace();
> throw new IllegalStateException("Method " + methodName
> + " from class " + o.getClass() + " threw an
> exception");
> }
> }
>
> /**
> * Sets the value of the field on the object. The object should have
a
> field
> * name <code>"_" + getFieldDescriptor().getFieldName()</code>.<br>
> * <b>Example </b>: Field name =<code>identification</code>, object
> * field name =<code>_identification</code>.
> *
> * @param o
> * The object
> * @param o1
> * The new value
> * @throws IllegalStateException
> * The Java object has changed and is no longer supported
> by
> * this handler, or the handler is not compatible with
the
> Java
> * object
> * @throws IllegalArgumentException
> */
> public void setValue(final Object o, final Object o1)
> throws IllegalStateException, IllegalArgumentException {
> final FieldDescriptor fd = getFieldDescriptor();
> String name = fd.getFieldName();
> final String methodName = "set".concat(
> name.substring(0, 1).toUpperCase()).concat(
> name.substring(1, name.length()));
> name = "_".concat(name);
>
> Class fieldClass = null;
> try {
> fieldClass = o.getClass().getDeclaredField(name).getType();
> final Field[] fields = fieldClass.getDeclaredFields();
> for (int i = 0; i < fields.length; i++) {
> if (fields[i].get(null).toString().equals(o1.toString()))
{
> final Method method =
> o.getClass().getMethod(methodName,
> new Class[] { fields[i].getType() });
> method.invoke(o, new Object[] { fields[i].get(null)
});
> break;
> }
> }
> } catch (NoSuchFieldException e) {
> e.printStackTrace();
> throw new IllegalStateException("Field " + name + " must
exist
> in "
> + o.getClass());
> } catch (NoSuchMethodException e) {
> e.printStackTrace();
> throw new IllegalStateException("Method " + methodName
> + " must exist in " + o.getClass());
> } catch (IllegalAccessException e) {
> e.printStackTrace();
> throw new IllegalStateException("Class " +
> fieldClass.getClass()
> + " must be accessible");
> } catch (InvocationTargetException e) {
> e.printStackTrace();
> throw new IllegalStateException("Method " + methodName
> + " from class " + fieldClass.getClass()
> + " threw an exception");
> }
> }
>
> /**
> * Creates a new instance of the object described by this field.
> *
> * @param o
> * The object for which the field is created
> * @return A new instance of the field's value
> * @throws IllegalStateException
> * This field is a simple type and cannot be instantiated
> */
> public Object newInstance(final Object o) throws
IllegalStateException
> {
> throw new UnsupportedOperationException();
> }
>
> /**
> * Creates a new instance of the object described by this field.
> *
> * @param o
> * The object for which the field is created
> * @param objects
> * The set of constructor arguments
> * @return A new instance of the field's value
> * @throws IllegalStateException
> * This field is a simple type and cannot be instantiated
> */
> public Object newInstance(final Object o, final Object[] objects)
> throws IllegalStateException {
> throw new UnsupportedOperationException();
> }
>
> /**
> * Sets the value of the field to a default value. Reference fields
are
> set
> * to null, primitive fields are set to their default value,
collection
> * fields are emptied of all elements.
> *
> * @param o
> * The object
> * @throws IllegalStateException
> * The Java object has changed and is no longer supported
> by
> * this handler, or the handler is not compatiale with
the
> Java
> * object
> * @throws IllegalArgumentException
> */
> public void resetValue(final Object o) throws IllegalStateException,
> IllegalArgumentException {
> throw new UnsupportedOperationException();
> }
>
> }
>
>
> My mapping.xml snippets
>
>
>
>
>
> <class name="databean.types.Subjects"
> access="shared"
> verify-constructable="false"
> auto-complete="true">
>
> </class>
>
> <class
> name="databean.impl.SubjectDataResponse"
> access="shared"
> auto-complete="false">
> <map-to xml="subjectDataResponse" />
> <cache-type type="count-limited" />
>
> <field name="subjects"
>
> type="databean.types.Subjects"
>
> handler="marshalling.HmsiEnumTypeFieldHandler"
> get-method="getSubjects"
> set-method="setSubjects"
> collection="arraylist">
> <bind-xml name="subjects" />
> </field>
>
> </class>
>
>
>
>
>
>
>
> Thanks
> Ram
>
>
>
> |---------+---------------------------->
> | | Ram Sarma |
> | | |
> | | 01/11/2005 10:00 |
> | | AM |
> | | |
> |---------+---------------------------->
>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
> |
|
> | To: castor-dev@exolab.org
|
> | cc:
|
> | Subject: TypeSafe Enums and Collections(Document link: Ram
Sarma)
|
>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
>
>
>
> hey,
>
> Was wondering if anyone got typesafe enums and collections to work
> together. I have a class say A which has a field which returns a
collection
> of type safe enums B. When I use the mapping.xml (which has
> verify-constructable = false and auto-complete = true for the type safe
> enum B and class B also has a static valueOf method and a toString
method).
> The resulting XML generated does not contain data from B instead simply
> contains a chunk of <B/> tags. I saw a posting sometime
> back about the same but there was no replies for it.
>
> I was wondering if someone had gotten this to work.
>
> Thanks
> Ram
>
>
>
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