Getting Absolute Path of a Job

[Yarlee]

I am trying to develop a plugin wherein I will need access to the full path 
of a job .. For example if my http://example.com/job/test/2 is the absolute 
url of my job .. in perform I get access to (AbstractBuild ) build object 
and build.getUrl gives only test/2 how to get full url including the 
hostname 

Thanks