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From "Donnie Hale" <don...@haleonline.net>
Subject RE: Digester yielding IllegalAccessException in CallMethodRule, SetNextRule
Date Sat, 08 Dec 2001 17:08:30 GMT
+1

There's no reason, to my mind, that reflection-based behavior should be
different than direct all behavior.

Donnie


> -----Original Message-----
> From: robert burrell donkin [mailto:robertdonkin@mac.com]
> Sent: Saturday, December 08, 2001 8:33 AM
> To: Jakarta Commons Developers List
> Subject: Re: Digester yielding IllegalAccessException in CallMethodRule,
> SetNextRule
>
>
> i've played around the example code and craig's diagnosis seems to be
> correct (as usual :)
>
> the Method.getMethod used by digester returns the inner implementation
> which is only accessible within the package rather than the public
> interface implementation.
>
> this problem can be fixed - in my test harness - by using the
> PropertyUtils.getAccessibleMethod to find an accessible version of the
> method. unfortunately, this method is currently private in PropertyUtils.
> this is a method which is needed by PropertyUtils but doesn't really
> belong in there (it's a general method finder method rather than a
> property finder method).
>
> maybe the right thing to do would be to add a new class (in beanutils) -
> MethodUtils? - which would contain the general method-related
> methods from
> PropertyUtils and which exposed them as public methods. other utility
> method-related reflection methods could be added later. the public
> interface for PropertyUtils could be maintained but the private
> implementations would be moved into this new class. digester could them
> use the improved reflection methods in this new class.
>
> i'm willing to create patches if this plan is acceptable.
>
> - robert
>
>
> On Thursday, December 6, 2001, at 02:04 AM, Donnie Hale wrote:
>
> > See below...
> >
> > Donnie
> >
> >
> >> -----Original Message-----
> >> From: craigmcc@localhost [mailto:craigmcc@localhost]On Behalf Of Craig
> >> R. McClanahan
> >> Sent: Wednesday, December 05, 2001 1:41 AM
> >> To: Jakarta Commons Developers List
> >> Subject: RE: Digester yielding IllegalAccessException in
> CallMethodRule,
> >> SetNextRule
> >>
> >>
> >>
> >>
> >> On Tue, 4 Dec 2001, Donnie Hale wrote:
> >>
> >>> Date: Tue, 4 Dec 2001 22:44:09 -0500
> >>> From: Donnie Hale <donnie@haleonline.net>
> >>> Reply-To: Jakarta Commons Developers List
> >> <commons-dev@jakarta.apache.org>
> >>> To: Jakarta Commons Developers List <commons-dev@jakarta.apache.org>
> >>> Subject: RE: Digester yielding IllegalAccessException in
> CallMethodRule,
> >>>      SetNextRule
> >>>
> >>> Craig,
> >>>
> >>> Thanks for the prompt response. If I understand your second
> >> case, I tried
> >>> it, and it worked as I wanted:
> >>>
> >>> // Callback.java
> >>> public class Callback implements Reader.WebXmlFileDigestion
> >>> {
> >>>     public Callback(Driver d)
> >>>     {
> >>>         driver_ = d;
> >>>     }
> >>>
> >>>     public void parseError(Throwable t) throws Exception
> >>>     {
> >>>         t.printStackTrace();
> >>>     }
> >>>
> >>>     public void setServletMapping(
> >>>         String servletName, String urlPattern)
> >>>     {
> >>>         driver_.addServletMapping(servletName, urlPattern);
> >>>     }
> >>>
> >>>     Driver driver_;
> >>> }
> >>>
> >>> Then, in Driver.java, I used
> >>>
> >>>         reader.digestWebXmlFile(new Callback(this));
> >>>
> >>> instead of passing the anonymous implementing class.
> >>>
> >>
> >> OK, so we know it definitely has something to do with visibility of the
> >> called class.
> >>
> >>> I'll have to see if I have Sun's 1.3 JDK around to try. If not,
> >> it could be
> >>> a while, as I only have IDSL access. :)
> >>>
> >>> One more, related, thing, since you're in the know.
> >>
> >> I better be, since I wrote Digester :-).
> >>
> >>> Is it possible to
> >>> implement an interface with methods which have package scope
> though the
> >>> interface methods are public? I don't care that some unknown
> >> future entity
> >>> implements the interface; but I don't want the methods in the
> >> implementation
> >>> of it that I care about to be publicly accessible. My copy of
> >> the language
> >>> spec is at work...
> >>>
> >>
> >> I'm sure it's feasible to implement access via reflection
> (which is what
> >> Digester uses) to methods defined public through an interface - we ran
> >> into a similar case in BeanUtils and solved it be looking up an
> >> appropriate java.lang.reflect.Method object correctly.  I'm
> not sure what
> >> happens when you shadow a package-private method with a public one --
> >> will
> >> have to check on that.  However, AFAIK, the class itself has
> to be public
> >> for any of this to work.
> >
> > Is the requirement of the class being public an artifact of doing this
> > through reflection. If not, I don't understand. As an example, I've got
> > this
> > code in an app:
> >
> >         File dir = new File(dirName);
> >         String[] fileList = dir.list(
> >             new FilenameFilter()
> >             {
> >                 public boolean accept(java.io.File file,
> java.lang.String
> > name)
> >                 {
> >                     return name.toLowerCase().endsWith(fileSuffix);
> >                 }
> >             });
> >
> > Clearly, the File.list method needs an impl of FilenameFilter
> on which to
> > make callbacks. I'm providing it one, anonymously. I'm sure,
> though, that
> > the callback is direct - not via reflection. This works find for me.
> >
> > I guess that's my main source of confusion about the whole thing.
> >
> >
> >
> >>
> >>> Thanks much,
> >>>
> >>> Donnie
> >>>
> >>
> >> Craig
> >>
> >>
> >>>
> >>> -----Original Message-----
> >>> From: craigmcc@localhost [mailto:craigmcc@localhost]On Behalf Of Craig
> >>> R. McClanahan
> >>> Sent: Tuesday, December 04, 2001 10:08 PM
> >>> To: Jakarta Commons Developers List
> >>> Subject: Re: Digester yielding IllegalAccessException in
> CallMethodRule,
> >>> SetNextRule
> >>>
> >>>
> >>> Hi Donnie,
> >>>
> >>> IIRC, Digester only knows how to call public methods of public
> >> classes --
> >>> and an anonymous inner class isn't public.
> >>>
> >>> Could you try two things for me?
> >>> * Try this under the Sun JDK just to see if the behavior is different
> >>> * Try this where the driver class is a regular public class,
> >>>   rather than an inner class
> >>>
> >>> That will help us narrow down where the difficulty is.
> >>>
> >>> Craig
> >>>
> >>>
> >>> On Tue, 4 Dec 2001, Donnie Hale wrote:
> >>>
> >>>> Date: Tue, 4 Dec 2001 22:15:20 -0500
> >>>> From: Donnie Hale <donnie@haleonline.net>
> >>>> Reply-To: Jakarta Commons Developers List
> >> <commons-dev@jakarta.apache.org>
> >>>> To: commons-dev@jakarta.apache.org
> >>>> Subject: Digester yielding IllegalAccessException in CallMethodRule,
> >>>>      SetNextRule
> >>>>
> >>>> I searched the list archives and didn't see anything directly
> >> on-topic.
> >>>> Sorry if I missed it. Also, this is likely a normal Java
> >> issue, but I'm
> >>> not
> >>>> getting it. :(
> >>>>
> >>>> Here's a very pared down example which reproduces my problem exactly:
> >>>>
> >>>> // Driver.java
> >>>> public class Driver
> >>>> {
> >>>>     public static void main(String[] args)
> >>>>     {
> >>>>         try
> >>>>         {
> >>>>             Driver driver = new Driver();
> >>>>             driver.parseWebApp(new Reader());
> >>>>         }
> >>>>         catch (Exception e)
> >>>>         {
> >>>>             e.printStackTrace();
> >>>>         }
> >>>>     }
> >>>>
> >>>>     public void Driver()
> >>>>     {
> >>>>     }
> >>>>
> >>>>     public void parseWebApp(Reader reader) throws Exception
> >>>>     {
> >>>>         reader.digestWebXmlFile(
> >>>>             new Reader.WebXmlFileDigestion()
> >>>>             {
> >>>>                 public void parseError(Throwable t) throws Exception
> >>>>                 {
> >>>>                     t.printStackTrace();
> >>>>                 }
> >>>>
> >>>>                 public void setServletMapping(
> >>>>                     String servletName, String urlPattern)
> >>>>                 {
> >>>>                     addServletMapping(servletName, urlPattern);
> >>>>                 }
> >>>>             }
> >>>>         );
> >>>>     }
> >>>>
> >>>>     public void addServletMapping(String servletName, String
> >> urlPattern)
> >>>>     {
> >>>>         System.out.println("Mapping read: " + servletName + " =>
" +
> >>>> urlPattern);
> >>>>     }
> >>>> }
> >>>>
> >>>> // Reader.java
> >>>> import java.io.InputStream;
> >>>> import java.io.IOException;
> >>>> import java.net.URL;
> >>>> import org.xml.sax.Attributes;
> >>>> import org.xml.sax.SAXException;
> >>>> import org.apache.commons.digester.Digester;
> >>>> import org.apache.commons.digester.Rule;
> >>>>
> >>>> public class Reader
> >>>> {
> >>>>     public static interface WebXmlFileDigestion
> >>>>     {
> >>>>         public void parseError(Throwable t) throws Exception;
> >>>>
> >>>>         public void setServletMapping(String servletName, String
> >>>> urlPattern);
> >>>>     }
> >>>>
> >>>>     public void Reader()
> >>>>     {
> >>>>     }
> >>>>
> >>>>     public void digestWebXmlFile(WebXmlFileDigestion callback)
> >>>>         throws Exception
> >>>>     {
> >>>>         // Prepare a Digester to scan the web application deployment
> >>>> descriptor
> >>>>         Digester digester = new Digester();
> >>>>         digester.push(callback);
> >>>>         digester.setDebug(1);
> >>>>         digester.setNamespaceAware(true);
> >>>>         digester.setValidating(false);
> >>>>
> >>>>         // Register our local copy of the DTDs that we can find
> >>>>         for (int i = 0; i < registrations_.length; i += 2)
> >>>>         {
> >>>>             URL url =
> >> this.getClass().getResource(registrations_[i+1]);
> >>>>             if (url != null)
> >>>>             {
> >>>>                 digester.register(registrations_[i], url.toString());
> >>>>             }
> >>>>         }
> >>>>
> >>>>         // Configure the processing rules that we need
> >>>>         digester.addCallMethod("web-app/servlet-mapping",
> >>>>             "setServletMapping", 2);
> >>>>
> >> digester.addCallParam("web-app/servlet-mapping/servlet-name", 0);
> >>>>
> >> digester.addCallParam("web-app/servlet-mapping/url-pattern", 1);
> >>>>
> >>>>         InputStream input= null;
> >>>>         try
> >>>>         {
> >>>>             input = this.getClass().getResourceAsStream("web.xml");
> >>>>             digester.parse(input);
> >>>>         }
> >>>>         catch (Throwable e)
> >>>>         {
> >>>>             callback.parseError(e);
> >>>>         }
> >>>>         finally
> >>>>         {
> >>>>             if (input != null)
> >>>>             {
> >>>>                 input.close();
> >>>>             }
> >>>>         }
> >>>>     }
> >>>>
> >>>>     protected static final String registrations_[] =
> >>>>     {
> >>>>         "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN",
> >>>>         "/org/apache/struts/resources/web-app_2_2.dtd",
> >>>>         "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN",
> >>>>         "/org/apache/struts/resources/web-app_2_3.dtd"
> >>>>     };
> >>>> }
> >>>>
> >>>> The object on which the method call is to be invoked is an
> >> instance of an
> >>>> anonymous inner class which implements a public (nested)
> >> interface. All
> >>> the
> >>>> methods on the interface and its anonymous implementation are
> >> public. All
> >>>> the methods on Driver and Reader are public. Yet when I run
> >> this, I get:
> >>>>
> >>>> java.lang.IllegalAccessException: Driver$1
> >>>>         at java.lang.reflect.Method.invoke(Native Method)
> >>>>         at
> >>>>
> >> org.apache.commons.digester.CallMethodRule.end(CallMethodRule.java:308)
> >>>>         at
> >>>> org.apache.commons.digester.Digester.endElement(Digester.java:757)
> >>>>         at
> >>>> org.apache.xerces.parsers.SAXParser.endElement(SAXParser.java:1403)
> >>>>         at
> >>>>
> >>>
> >> org.apache.xerces.validators.common.XMLValidator.callEndElement(XM
> >> LValidator
> >>>> .java:1480)
> >>>>         at
> >>>>
> >>>
> >> org.apache.xerces.framework.XMLDocumentScanner$ContentDispatcher.d
> >> ispatch(XM
> >>>> LDocumentScanner.java:1149)
> >>>>         at
> >>>>
> >>>
> >> org.apache.xerces.framework.XMLDocumentScanner.parseSome(XMLDocume
> >> ntScanner.
> >>>> java:381)
> >>>>         at
> >>> org.apache.xerces.framework.XMLParser.parse(XMLParser.java:1081)
> >>>>         at
> >> org.apache.commons.digester.Digester.parse(Digester.java:1206)
> >>>>         at Reader.digestWebXmlFile(Reader.java:53)
> >>>>         at Driver.parseWebApp(Driver.java:23)
> >>>>         at Driver.main(Driver.java:9)
> >>>>
> >>>> I'm guessing this has something to do with the "Driver$1" being the
> >>>> classname. But it sure seems like I've done stuff like this
> >> before, just
> >>>> possibly not through reflection. Do I have to go to the
> >> extreme of making
> >>>> the interface implementation non-anonymous to have any hope
> of getting
> >>> this
> >>>> to work?
> >>>>
> >>>> BTW, I'm using IBM's JDK 1.3 on Win2K.
> >>>>
> >>>> Thanks much,
> >>>>
> >>>> Donnie
> >>>>
> >>>>
> >>>> --
> >>>> To unsubscribe, e-mail:
> >>> <mailto:commons-dev-unsubscribe@jakarta.apache.org>
> >>>> For additional commands, e-mail:
> >>> <mailto:commons-dev-help@jakarta.apache.org>
> >>>>
> >>>>
> >>>
> >>>
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> >>> For additional commands, e-mail:
> >>> <mailto:commons-dev-help@jakarta.apache.org>
> >>>
> >>>
> >>>
> >>> --
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> >>> For additional commands, e-mail:
> >> <mailto:commons-dev-help@jakarta.apache.org>
> >>>
> >>>
> >>
> >>
> >> --
> >> To unsubscribe, e-mail:
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> >> For additional commands, e-mail:
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> >>
> >>
> >
> >
> > --
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> org>
> For additional commands, e-mail: <mailto:commons-dev-help@jakarta.apache.
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