When I click a URL in the application it opens a PDF file.

This PDF file contains a link. When I hit this link , it opens a new browser which displays the required contents. If I try to hit the URL which is displayed in the address in another browser, it agains open a new browser with the required contents.
As per my requirement, this should not happen (i.e it must not open again a new browser window) means the new url needs to be opened only when it is opened from a frame or only when it is opened from the specified source pdf file where the link is present.

We are using a java script within a servlet for opening a new browser and jsp to display the contents. Kindly help me in solving this issue asap.