-------------
-- General problem description:
-------------

Under Netbeans 4.0 and higher, we cannot use
org.openide.explorer.propertysheet.editors.XMLPropertyEditor when building
property editors for our visual components. We use this interface on our
property editors for Netbeans, and include a copy of the above class file in our
jar because we also support all other IDEs (Eclipse, JBuilder) and need this
interface present for obvious reasons there.

The error is visible when you open a form generated with our wizard that uses
the OSetName (XTT defined) property.  Our XMLPropertyEditor does not read this
property.  Attached are a few screen shots showing the warning and error in the
IDE, and a text file showing the exception thrown.

-----------------
-- Temporary patch is attached
-----------------

Also attached are our patches for both 4.0 and 4.1Beta. They would go under
ideX\modules\patches\org-netbeans-modules-form where ideX is ide4 or ide5
depending on the NB version.

The current changes are all in class GandalfPersistenceManager although my
strong suggestion is that it is the classloader used for the ui that should be
ultimately fixed.

---------------------
--- Details of the problem:
---------------------

The real problem is at line 1747 of
org.netbeans.modules.form.GandalfPersistenceManager :

       if (prEd instanceof XMLPropertyEditor) {
 
In that prEd and XMLPropertyEditor are loaded by different classloaders that are
not in the same classloader “chain” and therefore instanceof will always return
false. 

Please open attached Debugger.jpg picture at this point.

As you can see from the last 2 watches, the XMLPropertyEditor is loaded by
org.netbeans.Main$BootClassLoader and our OSetsPropertyEditor is loaded by
org.netbeans.api.java.classpath.ClassLoaderSupport. That would not be bad if
ClassLoaderSupport would deffer to org.netbeans.Main$BootClassLoader before
trying to perform a class load – but it does not.

My initial feeling is that as ClassLoaderSupport relies on NbClassLoader  to
defer the findClass to the system class loader, and NbClassLoader obtains the
wrong parent classloader from its constructor:
 

       super(new URL[0], systemClassLoader());

 

In the debugger the call to systemClassLoader() returns a classloader that has
nothing to do with org.netbeans.Main$BootClassLoader .


Our fix has been to supplement the if (prEd instanceof XMLPropertyEditor) part
with extra code that uses the correct classloader to the same effect. Here is an
excerpt from the fixed code:

                            if (prEd instanceof XMLPropertyEditor) {
                                // the value is saved by XMLPropertyEditor
                                for (int j=0; j < n; j++) {
                                    if (children.item(j).getNodeType()
                                        == org.w3c.dom.Node.ELEMENT_NODE)
                                    {   // here is the element of stored value
                                        ((XMLPropertyEditor)prEd).readFromXML(
                                                              children.item(j));
                                        value = prEd.getValue();
                                        break;
                                    }
                                }
                            }
                            // InsiTech patch for non-Netbeans property editors
that use the XMLPropertyEditor interface
                            if ( value == NO_VALUE){
                                value = patchReadFromXML(prEd , children, n ,
value);
                            }   // if ( value == NO_VALUE)


The patchReadFromXML method looks like this:
    private Object patchReadFromXML(PropertyEditor prEd, org.w3c.dom.NodeList
children, int n, Object value ) throws Exception {
        ClassLoader editorClassLoader = prEd.getClass().getClassLoader();
        Class xmlPropertyEditorClass =
editorClassLoader.loadClass("org.openide.explorer.propertysheet.editors.XMLPropertyEditor");
        if ( xmlPropertyEditorClass != null){
            if ( xmlPropertyEditorClass.isAssignableFrom(prEd.getClass())){
                // the value is saved by XMLPropertyEditor
                Method m = prEd.getClass().getMethod("readFromXML" , new
Class[]{org.w3c.dom.Node.class});
                if ( m != null){
                    for (int j=0; j < n; j++) {
                        if (children.item(j).getNodeType()
                            == org.w3c.dom.Node.ELEMENT_NODE)
                        {   // here is the element of stored value 

                            m.invoke(prEd, new Object[]{ children.item(j)});
                            return  prEd.getValue();
                        }
                    }
                }
            }
        }
        return value;   // return original value
    }

Please see the full source code for this in the attached patches
(form_patch_40.jar and form_patch_41Beta.jar).

Again this is just a temporary patch - I feel strongly the the classloader chain
should be properly fixed. 

Thanks,
David