'javax.naming.directory.InitialDirContext'

想通过安卓应用连接openfire服务器，使用了smack的jar包。
但是出现Could not find class 'javax.naming.directory.InitialDirContext'错误。查了一下，stackoverflow上有人解释说：

Thats because jars use core libraries. Android does not support all J2SE packages, but rather a subset of it: http://developer.android.com/reference/packages.html

但我还是没解决，有人遇到过这个问题嘛

http://developer.classpath.org/doc/javax/naming/directory/InitialDirContext-source.html