I want to determine the website from which the request to the particular website has been called. For Example..I have a website www.ex.com. Now this website link has been there on three websites www.a.com, www.b.com, and www.c.com. Suppose one user has clicked the link from www.a.com to go to www.ex.com. Now I want to determine that the request has come from the www.a.com and then the page in www.ex.com will be displayed accordingly. Similarly if the user has clicked the www.ex.com link from www.b.com then the page will be displayed accordingly.
So how can I determine this request source, means from which website www.ex.com has been called? It is good if you will explain this using code in PHP and JAVA.