Handling HTTP request redirect in java

Handling HTTP request redirect in java

I'm writing a network android application that uses http requests to get
data. The data is HTML format. I use Apache HttpClient and JSoup.
When I'm out of traffic with my mobile internet provider, I am always
redirected to the providers' page saying that I should pay some money. Of
course, it is a bad idea to parse this page.
How to detect occured page substitution?