log4j:ERROR A "org.apache.log4j.ConsoleAppender" object is not assignable to a "org.apache.log4j.Appender" variable.
启动参数中增加 -Dlog4j.ignoreTCL=true
这样就可以让common logging 跟log4j同时使用
http://stackoverflow.com/questions/11719218/classloading-issue-with-osgi