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18846 Views 13 Replies Latest reply: Jun 23, 2011 12:16 AM by duncancarroll RSS
Bronze
Mike Ryan
12 posts since
Feb 11, 2005
Currently Being Moderated

Jan 18, 2008 1:16 PM

Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

 

I think this is a bit of a long shot but I figured I might as well give this a try.

 

 

 

 

 

So I'm using this patched version of the Smack API with the Google Phone Android SDK to try to get a custom client working on that platform.  What I keep running into in different places are ClassCastExceptions when the API tries to cast Packets into subclasses.

 

 

Here's an example from the ServiceDiscoveryManager

 

 

         PacketCollector collector =

            connection.createPacketCollector(new PacketIDFilter(disco.getPacketID()));

 

        connection.sendPacket(disco);

 

        // Wait up to 5 seconds for a result.

        IQ result = (IQ) collector.nextResult(SmackConfiguration.getPacketReplyTimeout());

        // Stop queuing results

        collector.cancel();

        if (result == null) {

            Log.i("TestClient", "++++ No response from the server.");

        }

        if (result.getType() == IQ.Type.ERROR) {

            Log.i("TestClient",result.getError().toString());

        }

        Log.i("TestClient", ">>>> \"" + result.getClass().getName()+"\"");

        Packet test = (Packet) result;

        Log.i("TestClient", "Result class loader: " + test.getClass().getClassLoader().toString());

        Log.i("TestClient", "DI Class loader: " + DiscoverItems.class.getClassLoader().toString());

 

        return (DiscoverItems) test;

 

 

 

 

 

the cast of the Packet to DiscoverItems will fail with a ClassCastException.   As you can see from the Log statements  in this case I've even made sure the Class loaders are the same and that the Class is the parent class. I can even successfully cast it to a Packet but not to a sub class.

 

 

Any help would be appreciated before I pull my hair out.

 

 

 

 

 

Thanks.

 

 

  • Bronze
    Mike Ryan
    12 posts since
    Feb 11, 2005
    Currently Being Moderated
    Jan 21, 2008 11:17 AM (in response to Mike Ryan)
    Re: Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

     

    One other data point.  when I log the class type I keep getting this:

     

     

    "org.jivesoftware.smack.PacketReader$4"

     

     

      i can't really tell why.

     

     

    • Gaston Dombiak Jiver
      Gaston Dombiak
      3,863 posts since
      Sep 26, 2001
      Currently Being Moderated
      Jan 21, 2008 4:43 PM (in response to Mike Ryan)
      Re: Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

      Hey Mike,

       

      That usually happens when smackx.jar is missing in the classpath. When this problem happens with custom classes (i.e. classes that you implemented) then it could be a problem of registering your extension as a PacketExtension or IQExtension.

       

      Regards,

       

        -- Gato

      • Bronze
        Mike Ryan
        12 posts since
        Feb 11, 2005
        Currently Being Moderated
        Jan 21, 2008 5:54 PM (in response to Gaston Dombiak)
        Re: Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

         

        So after mucking around a bunch I tracked it down to a ProviderManager issue, on this platform the smack.providers isn't getting either read or the ClassLoader isn't  working.   I'm not really a Java guy so I'm not totally up on the way the ClassLoaders work but it doesn't seem to be working properly on here.  I've had other similar issues with a couple of Smack classes that use static loaders to attach themselves to the XMPPConnection class.

         

         

         

         

         

        I eventually got this working by manually configuring the providers in the provider manager.  Probably not the best solution but its working for me so far.

         

         

  • Bronze
    Mike Ryan
    12 posts since
    Feb 11, 2005
    Currently Being Moderated
    Apr 3, 2008 10:41 PM (in response to Mike Ryan)
    Re: Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

     

    Ok so I've gotten a few questions about this so I guess I should really answer my own question

     

     

     

     

     

    From what I can tell each provider has a static function that registers it with the provider manage this usually happens on class load but this isn't working with Android so none of the providers are getting registered with the provider manager.  However you can do that manually.  So I have a function like so:

     

     

    You can call it with configure(ProviderManager.getInstance())  I do this before calling new XMPPConnection()

     

     

     

     

     

        public void configure(ProviderManager pm) {

     

            //  Private Data Storage

            pm.addIQProvider("query","jabber:iq:private", new PrivateDataManager.PrivateDataIQProvider());

     

     

            //  Time

            try {

                pm.addIQProvider("query","jabber:iq:time", Class.forName("org.jivesoftware.smackx.packet.Time"));

            } catch (ClassNotFoundException e) {

                Log.w("TestClient", "Can't load class for org.jivesoftware.smackx.packet.Time");

            }

     

            //  Roster Exchange

            pm.addExtensionProvider("x","jabber:x:roster", new RosterExchangeProvider());

     

            //  Message Events

            pm.addExtensionProvider("x","jabber:x:event", new MessageEventProvider());

     

            //  Chat State

            pm.addExtensionProvider("active","http://jabber.org/protocol/chatstates", new ChatStateExtension.Provider());

     

            pm.addExtensionProvider("composing","http://jabber.org/protocol/chatstates", new ChatStateExtension.Provider());

     

            pm.addExtensionProvider("paused","http://jabber.org/protocol/chatstates", new ChatStateExtension.Provider());

     

            pm.addExtensionProvider("inactive","http://jabber.org/protocol/chatstates", new ChatStateExtension.Provider());

     

            pm.addExtensionProvider("gone","http://jabber.org/protocol/chatstates", new ChatStateExtension.Provider());

     

            //  XHTML

            pm.addExtensionProvider("html","http://jabber.org/protocol/xhtml-im", new XHTMLExtensionProvider());

     

            //  Group Chat Invitations

            pm.addExtensionProvider("x","jabber:x:conference", new GroupChatInvitation.Provider());

     

            //  Service Discovery # Items    

            pm.addIQProvider("query","http://jabber.org/protocol/disco#items", new DiscoverItemsProvider());

     

            //  Service Discovery # Info

            pm.addIQProvider("query","http://jabber.org/protocol/disco#info", new DiscoverInfoProvider());

     

            //  Data Forms

            pm.addExtensionProvider("x","jabber:x:data", new DataFormProvider());

     

            //  MUC User

            pm.addExtensionProvider("x","http://jabber.org/protocol/muc#user", new MUCUserProvider());

     

            //  MUC Admin    

            pm.addIQProvider("query","http://jabber.org/protocol/muc#admin", new MUCAdminProvider());

     

     

            //  MUC Owner    

            pm.addIQProvider("query","http://jabber.org/protocol/muc#owner", new MUCOwnerProvider());

     

            //  Delayed Delivery

            pm.addExtensionProvider("x","jabber:x:delay", new DelayInformationProvider());

     

            //  Version

            try {

                pm.addIQProvider("query","jabber:iq:version", Class.forName("org.jivesoftware.smackx.packet.Version"));

            } catch (ClassNotFoundException e) {

                //  Not sure what's happening here.

            }

     

            //  VCard

            pm.addIQProvider("vCard","vcard-temp", new VCardProvider());

     

            //  Offline Message Requests

            pm.addIQProvider("offline","http://jabber.org/protocol/offline", new OfflineMessageRequest.Provider());

     

            //  Offline Message Indicator

            pm.addExtensionProvider("offline","http://jabber.org/protocol/offline", new OfflineMessageInfo.Provider());

     

            //  Last Activity

            pm.addIQProvider("query","jabber:iq:last", new LastActivity.Provider());

     

            //  User Search

            pm.addIQProvider("query","jabber:iq:search", new UserSearch.Provider());

     

            //  SharedGroupsInfo

            pm.addIQProvider("sharedgroup","http://www.jivesoftware.org/protocol/sharedgroup", new SharedGroupsInfo.Provider());

     

            //  JEP-33: Extended Stanza Addressing

            pm.addExtensionProvider("addresses","http://jabber.org/protocol/address", new MultipleAddressesProvider());

     

            //   FileTransfer

            pm.addIQProvider("si","http://jabber.org/protocol/si", new StreamInitiationProvider());

     

            pm.addIQProvider("query","http://jabber.org/protocol/bytestreams", new BytestreamsProvider());

     

            pm.addIQProvider("open","http://jabber.org/protocol/ibb", new IBBProviders.Open());

     

            pm.addIQProvider("close","http://jabber.org/protocol/ibb", new IBBProviders.Close());

     

            pm.addExtensionProvider("data","http://jabber.org/protocol/ibb", new IBBProviders.Data());

     

            //  Privacy

            pm.addIQProvider("query","jabber:iq:privacy", new PrivacyProvider());

     

            pm.addIQProvider("command", "http://jabber.org/protocol/commands", new AdHocCommandDataProvider());

            pm.addExtensionProvider("malformed-action", "http://jabber.org/protocol/commands", new AdHocCommandDataProvider.MalformedActionError());

            pm.addExtensionProvider("bad-locale", "http://jabber.org/protocol/commands", new AdHocCommandDataProvider.BadLocaleError());

            pm.addExtensionProvider("bad-payload", "http://jabber.org/protocol/commands", new AdHocCommandDataProvider.BadPayloadError());

            pm.addExtensionProvider("bad-sessionid", "http://jabber.org/protocol/commands", new AdHocCommandDataProvider.BadSessionIDError());

            pm.addExtensionProvider("session-expired", "http://jabber.org/protocol/commands", new AdHocCommandDataProvider.SessionExpiredError());

        }

          

     

     

  • gperrot Bronze
    gperrot
    11 posts since
    Jul 1, 2008
    Currently Being Moderated
    Jul 1, 2008 12:53 AM (in response to Mike Ryan)
    Re: Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

     

    Hello, i have a problem with the vCard.load function that does nothing in an Android application but works well with a J2SE project.

     

     

    To fix that problem, I tried to add the following line before creating the connection : ProviderManager.getInstance().addIQProvider("vCard", "vcard-temp", new VCardProvider());

     

     

    Since i added this, i have my listener function connectionClosedOnError (from ConnectionListener) which is called just after the first call to vCard.load...

     

     

    I tried with the standard smack jars and also the ones provided by the bhoost project: same result with and without the code line above.

     

     

    • Vincent BARAT Bronze
      Vincent BARAT
      1 posts since
      Jul 2, 2008
      Currently Being Moderated
      Jul 2, 2008 5:56 AM (in response to gperrot)
      Re: Shot in the dark - Smack API, Android SDK and ClassCastExceptions.

      I faced the same issue and found a fix.

       

      Actually, on Android, smack don't take into account everything that is part of the smack.jar and smackx.jar meta data (basically, the content of the files "smack-config.xml and smack.provider is ignored) which explain why the various packet providers must be initialized by hand. I guess that the META-INF section is discarded when Android convert the .jar inot its private format.

       

      Then, regarding your precise problem, I manage to fix this by  applying the following patch:

       

      

Index: source/org/jivesoftware/smackx/provider/VCardProvider.java
===================================================================
--- source/org/jivesoftware/smackx/provider/VCardProvider.java  (revision 10629)
+++ source/org/jivesoftware/smackx/provider/VCardProvider.java  (working copy)
@@ -244,14 +244,16 @@
}

private void appendText(StringBuilder result, Node node) {
-            NodeList childNodes = node.getChildNodes();
-            for (int i = 0; i < childNodes.getLength(); i++) {
-                Node nd = childNodes.item(i);
-                String nodeValue = nd.getNodeValue();
-                if (nodeValue != null) {
-                    result.append(nodeValue);
+            if (node.hasChildNodes()) {
+                NodeList childNodes = node.getChildNodes();
+                for (int i = 0; i < childNodes.getLength(); i++) {
+                    Node nd = childNodes.item(i);
+                    String nodeValue = nd.getNodeValue();
+                    if (nodeValue != null) {
+                        result.append(nodeValue);
+                    }
+                    appendText(result, nd);
}
-                appendText(result, nd);
}
}
}

       

      I guess there is an error in the function that is visible only on Android because the org.w3c.dom package is not exactely the same then the one present in smack.jar but I'm not sure, since I'm not a Java expert. So, if somebody has information about this, he is welcome!

       

      Cheers,

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