jar中的AWS开发工具包NoClassDefFoundError用作smartfox的扩展

Question

I'm exporting a project to a jar that is used as a server extension in SmartFox, my project uses Amazon AWS SDK to upload some files to the cloud. The problem is that when I run the SmartFox it throws this exception:

Exception in thread "Thread-22" java.lang.NoClassDefFoundError: com/amazonaws/auth/AWSCredentials at...
Caused by: java.lang.ClassNotFoundException: com.amazonaws.auth.AWSCredentials
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 1 more

The AWSCredentials class is in the classpath, when I downloaded the SDK files I notice that there was a "third-party" folder with jars that the AWS may need, I wasn't sure if I had to add them to the classpath, so I did it, but nothing changed.. also my project is a regular java project, not a web project, could that be the problem? If that's the case I'm screwed cause I'm not allowed to change the project type.. Thanks for any help in advance...

Answer 1

The answer was pretty easy, SmartFox has a /SmartFoxServer_2X/SFS2X/extensions/__ lib __ directory where you are supposed to put all the jars that your extension jar may need.

I pasted all the "third-party" jars and the SDK jar itself inside this directory and it almost worked. The problem that I faced after that was an incompatibility between two jars from the same library (http-client from apache), one residing at __ lib __ and the other residing at /SmartFoxServer_2X/SFS2X/lib that contains all the jars that SmartFox uses.

I think the problem was that the SmartFox classloader was loading the http-client .class files from the jar located at /SmartFoxServer_2X/SFS2X/lib whose version was a bit older than the one I pasted from the Amazon third party libraries and didn't have a couple of methods that AWS needed. Anyway, I updated SmartFox to the lastest version and that did the trick. Of course I also could have pasted the jar from the __ lib __ folder to lib to have the same version.