Murray Altheim schrieb: > Simon Kitching wrote: >> Murray Altheim schrieb: > [...]Using the existing feature of the ClassUtil (without > modification), you >>> add your class mappings to ClassUtil's classmappings.xml file: >>> >>> public static final String MAPPINGS = "/ini/classmappings.xml"; >>> >>> then let WikiEngine instantiate them using the existing code: >>> >>> m_authenticationManager = (AuthenticationManager) >>> >>> ClassUtil.getMappedObject(AuthenticationManager.class.getName()); >>> m_authorizationManager = (AuthorizationManager) >>> ClassUtil.getMappedObject( >>> AuthorizationManager.class.getName()); >>> >>> I don't see how a modification of ClassUtil is necessary here. The real >>> grunt work is rewriting the two AA classes. But so far as I understand >>> your requirements, the existing machinery permits this. >> >> As you show above, the WikiEngine class explicitly casts the returned >> object to class AuthenticationManager. So I must *subclass* >> AuthenticationManager or this code will throw a ClassCastException at >> runtime. But I cannot subclass AuthenticationManager because it is >> final, and so are many of its important methods. > > No, please read again either what I wrote, the ClassUtil code, or the > contents of /etc/ini/classmappings.xml. ClassUtil receives a Class > name, but that's *not* the class it will use if there is an > alternative mapping set up in ClassUtil.MAPPINGS. If you modify > classmappings.xml you can instantiate your own classes, e.g.: > > <classmappings> > <mapping> > > <requestedClass>com.ecyrd.jspwiki.auth.AuthenticationManager</requestedClass> > > <mappedClass>com.acme.auth.MyAuthenticationManager</mappedClass> > </mapping> > <mapping> > > <requestedClass>com.ecyrd.jspwiki.render.AuthorizationManager</requestedClass> > > <mappedClass>com.acme.auth.MyAuthorizationManager</mappedClass> > </mapping> > </classmappings> > > There's no need to modify anything in JSPWiki's code, nor use the same > package names as JSPWiki to obtain the behaviour you want. Just map > to your desired, custom classes and your good to go. That's what > ClassUtil does. >
Thanks very much for your time Murray. However I am still reasonably sure that the final status of the AuthorizationManager *is* a problem (and I have been doing this Java thing for a few years now). Let's split up the code in WikiEngine into steps: (1) String reqClass = AuthenticationManager.class.getName(); (2) Object mgrObj = ClassUtil.getMappedObject(reqClass); (3) m_authenticationManager = (AuthenticationManager) mgrObj; Steps (1) and (2) are fine. Yes, it is possible to configure the classmappings.xml file to point to my custom implementation, and ClassUtil will happily load the Class, create an instance and return it. No problems here at all. But in (3), the attempt to cast the custom object to type com.eycrd.wiki.auth.AuthenticationManager will fail because it is not of that type. A ClassCastException will therefore occur and the WikiEngine will fail to initialise. The solution is simply to make the custom class subclass AuthenticationManager - but that is not possible because that class is final. Note that I've now got a solution that works for me; I have a custom jar with a reimplementation of the problem classes (without final qualifiers) and I have named the jar "_jspwiki_patch.jar", where the leading underscore causes the servlet engine picks it up before the real JSPWiki.jar (alphabetical order). But sometime it might be nice to either fix this in the jspwiki code or rip out the ClassUtils.getMappedObject calls and just replace them with "new".. Regards, Simon
