[jira] Commented: (WICKET-3105) [wicket-ioc] Make it possible to use javassist instead of cglib for proxy generation

["Igor Vaynberg (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/WICKET-3105?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12920860#action_12920860 ] 

Igor Vaynberg commented on WICKET-3105:
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how does javassist proxy final methods? as far as i know, just like cglib, it creates a subclass - which has the same limitation of not being able to override final methods. do you have any documentation on this or a testcase you can write up in a quickstart where javassist succeeds while cglib fails?

> [wicket-ioc] Make it possible to use javassist instead of cglib for proxy generation
> ------------------------------------------------------------------------------------
>
>                 Key: WICKET-3105
>                 URL: https://issues.apache.org/jira/browse/WICKET-3105
>             Project: Wicket
>          Issue Type: Improvement
>          Components: wicket-spring
>    Affects Versions: 1.4.12
>         Environment: spring 3.0.4; servlet 2.5, 3.0
>            Reporter: Attila Király
>
> I got bitten with the cglib limitation of not handling final methods. This is a real pain because it can result in cryptic exceptions (like "IllegalArgumentException: Protected method: [a method name what I didn't call explicitly]"). I have checked wicket jira and I see others have problem with cglib too (like the need for a non-private no-arg constructor). While javassist can not solve all these problems, but at least a few of it (final method proxying works but no-arg constructors still needed).
> So I suggest to modify wicket-ioc to support both cglib and javassist. Like this (refactoring and extending o.a.w.proxy.LazyInitProxyFactory class):
> - make an IProxyFactory interface as common ancestor. Make 3 classes implementing it (JdkProxyFactory for interfaces, CglibProxyFactory to reflect current class proxying and JavassistProxyFactory as the new implementation)
> - make an IProxyInvocationHandler interface and an AbstractProxyInvocationHandler to hold common interface superclasses and methods (currently as protected static presented in LazyInitProxyFactory)
> - make the 3 invocation handlers implement AbstractProxyInvocationHandler (2 are currently in LazyInitProxyFactory: JdkHandler and CGLibInterceptor and the 3rd would be the new JavassistMethodHandler)
> - make a new static classProxyFactory field in LazyInitProxyFactory that can be setted trough a public method. Its value should default to CglibProxyFactory (to be backward compatible).
> - modify LazyInitProxyFactory so it uses JdkProxyFactory for interfaces and the classProxyFactory for classes.
> - add javassist dependency to pom.xml as optional dependency (JavassistProxyFactory and JavassistMethodHandler should be outside of LazyInitProxyFactory class so they don't get loaded if they are not needed).
> In this way if someone wants to use javassist proxy instead of cglib only the followings are needed:
> - adding javassist to the dependent project's pom.
> - call LazyInitProxyFactory.setClassProxyFactory(new JavassistProxyFactory()); in the WebApplication init() method.
> I think these modifications could be made on the 1.4 branch too because they would not break the current public API of LazyInitProxyFactory (just add to it).
> Also could be made (but maybe these can't be done on the 1.4 branch because of compatibility):
> - pump cglib to 2.2 version from the current 2.1_3
> - factor cglib classes out from LazyInitProxyFactory and make cglib also an optional dependency
> I am willing to try to make a patch for this but first I would like to know the opinion of the wicket team about this.

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