[jira] Commented: (PIVOT-687) BXMLSerializer, would like to be able to specify a classloader for loading custom components

["Sandro Martini (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIVOT-687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12972883#action_12972883 ] 

Sandro Martini commented on PIVOT-687:
--------------------------------------

In an multi-layered application, a good thing would be to have a way for a caller to pass its (or maybe even a custom) Classloader instance to BXMLSerializer, so anytime a dynamic load of a class is needed, when that classloader is not null BXMLSerializer can use it instead of the default one (good for all standard cases).

Examples of Classloaders (for callers, to pass):
// ClassLoader classLoader = ClassLoader.getSystemClassLoader();  // clSystem
// ClassLoader classLoader = this.getClass().getClassLoader();  // clCurrent
// ClassLoader classLoader = Thread.currentThread().getContextClassLoader();  // clContext
Currently BXMLSerializer by default uses this:
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

Note that probably this is a good feature even in other places inside Pivot, whenever a dynamic load of a class has to be done, but this could be a later evolution (if needed here).
For example, I had a dedicated class for this, with the following methods (extract):
public DynamicLoader(String className, String variantName, int namingStrategy, boolean exceptionOnNull)
that was much more complex than needed here because I had to handle different naming strategies for class names. 
In my custom bean factory OptionalVariantBeanFactory i was loading classes using using DynamicLoader, and before loading the requested class I tried to load the optional variant version (specific for the given customer code) and if not found try to load the default class.
Probably all this is too business-specific for inclusion in Pivot, but a simplified version of DynamicLoader could be useful (maybe in the future).

	protected transient boolean     initClassToLoad = true;
	protected transient ClassLoader classloader     = null;

public void useClassloaderEnhanced(boolean initClass, ClassLoader cl)
this was using to enable the "enhanced" classloading, so later (inside the real load method) I could use
			if (classloader != null)
				clazz = Class.forName(fullClassName, initClassToLoad, classloader);
			else
				clazz = Class.forName(fullClassName);

just as a sample ...


> BXMLSerializer, would like to be able to specify a classloader for loading custom components
> --------------------------------------------------------------------------------------------
>
>                 Key: PIVOT-687
>                 URL: https://issues.apache.org/jira/browse/PIVOT-687
>             Project: Pivot
>          Issue Type: Improvement
>          Components: core-beans
>    Affects Versions: 2.0
>         Environment: all
>            Reporter: GBivins
>             Fix For: 2.0.1
>
>
> I'm running into issues trying to load my pivot window into a swing application. Some background,
> since pivot 2.0 can load components into a swing application, I've been trying to integrate pivot into a netbeans platform application.
> Only been at it a couple of hours but I'm stuck on an class loader issue. Basically, because I have pivot wrapped in separate module it's classloader
> can't references classes in any modules that depend on it. See here:
> http://bits.netbeans.org/dev/javadoc/org-openide-modules/org/openide/modules/doc-files/classpath.html#loader-hier
> I looked briefly in the docs but I'm not sure if I missed a readObject() signature that will allow me to pass in the classloader to use when de-serializing.

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