How to get standard parameter from URL

Now I have a requirement that I need to get the parameter from the URL.
For example:
http://localhost:8080/pluto/portal/__ws0x3pluto0x2AboutPortlet!
510736053|0_maximized?update=true

I want the get parameter 'update' and it's value 'true' in the pluto
container. I try to get it in the
PortletEnvironmentService->createRenderRequest, but the
request.getParameter() or request.getParameterValue() doesn't help.

Is there a way to doing this?