Thanks Sachin for the suggessions.
What we have done for now is as follow,
[1] Local WebLogic Server for development, we changed command script file C:\bea\weblogic700\server\bin\startWLS.cmd to include "-DInstance=Canada"
in the variable "MEM_ARGS=" then use the code System.getProperty("Instance").toLowerCase() for the instance name. Then to do dev
test we have to change the value of "-DInstance=Canada" for particular instance.
[2] For actual server QAT, UAT and PRD we have setup, we defined the attribute on console ex. Managed Server-->serverName-->configuartion-->Remote Start-->Arguments:-->-DInstance=Canada
Then code works same.
Thanks
Rakesh