如何使通知意图恢复而不是制定新的意图？

What i have here is a simple webview activity that when loaded it auto displays an ongoing notification. The idea is that people can navigate away from this activity and quickly access it again from any screen they want by pulling down the drop down menu and selecting it. Then when they want they can just close the notification by hitting the menu button and hitting exit and then the notification clears. This all works fine. However, when the notification is pressed it starts a new instance of the activity. What would i have to change to make it see if the activity has not already been destroyed and i can just call that instance back(resume it) and therefore not needing to load it again and won't need to add another activity to my stack. Any ideas? Any help would be greatly appreciated.What i have here is a simple webview activity t