Warning, this is a workaround and I give absolutely no warranty as to the results of trying this. Only use this if you really need a particular extension in order to move forward. It might may your JDeveloper to become unstable and cause your pets to come out in a rash. Right health and safety over.....
Those of you how are moving up to JDeveloper from 10.1.3 will notice that some of the extensions you know and love are not yet available in 11. This is mostly likely because the extension developer has been conservative in there bundle definition to restrict the usage in future versions. The good news is that that APIs for JDeveloper were frozen in 10.1.3 and for most part well written extensions should work. (You will note that the ones I have worked on will turn up in the center already as I tend to be more pragmatic about such things.)
You can work around this though with a little bit of work. First of all we need to capture the traffic between JDeveloper and the update center. To do this start the the HTTP Analyzer in JDeveloper. (View->HTTP Analyzer, Then press the green start start button) Then run the update tool Help->Check for Updates and proceed to the page you would normally see you extensions on. You can press cancel now as we have captured all the important information.
In my build the most important request goes to "http://www.oracle.com/technology/products/jdev/101/update/exchange.xml". So do a quick search of the response text, and yes you do have to copy the text to another editor to do this I have logged a bug for this, to find the extension you want. In my case I needed the spring extension and found this:
<u:update id="oracle.jdeveloper.spring2"> <u:name>JDeveloper Spring 2.5 Support</u:name> <u:version>08.01.09.01</u:version> <u:author>Oracle</u:author> <u:author-url>http://www.oracle.com/technology/products/jdev/htdocs/partners/addins/exchange/spring/spring-extension.html</u:author-url> <u:description> Adds support for creating and editing Spring 2.5 bean defintions. This addin will create the Spring 2.5.1 library and register the relevant XSDs and DTDs with the IDE to provide a productive editing experience for Spring definitions. </u:description> <!--u:post-startup-hook>oracle.jdevimpl.spring.addin.SpringAddinInstaller</u:post-startup-hook--> <u:requirements> <u:requires-extension id="oracle.jdeveloper" minVersion="10.1.3.36.73" maxVersion="10.1.3.9999" /> </u:requirements> <u:bundle-url>http://download.oracle.com/otn/java/jdeveloper/10131/extensions/JDeveloperSpring2.zip</u:bundle-url> </u:update>
Note the "requires" entry is the one that is causing problem. So we ignore this and just download the related zip file and place the contents in .../jdeveloper/jdev/extensions/ directory. This will not run any installer that comes with the extension; but should work in most cases.
In the spring case though you need to modify the name of the install directories. It appears that the long version numbers aren't liked by the more recent build of JDeveloper. You can discover this by looking at the libraries defined by the extension, Tools->Manage Libraries->Spring 2.5, and seeing where they are trying to find the jar files. In this case it seems we have to rename the extension jar and directory from "oracle.jdeveloper.spring2.08.01.09.01" to "oracle.jdeveloper.spring2.8". Now in theory you shouldn't need the version numbers at all; but but removing them didn't work in this case.
Next time you start JDeveloper you should find that in most cases the extension will work without problems. Even if you have an issue this should tide you over until the extension developer gets time to put another release out. When they do you may have to manually delete the extension before trying to install the new true extension from the update center. Also please disable this extension before reporting bugs on the forum to work out whether they are causing problems.
Right now I need to go back and figure out what I was working on and try to remember why I wanted the spring extension!