QuickTime for Java: A Developer's Notebook

Opening and Closing the QuickTime Session

All QTJ applications are responsible for managing the QuickTime “session.” The call to QTSession.open( ) gives QuickTime an opportunity to initialize itself, and it must be made before any other QTJ call, or you’ll get an exception. Similarly, you must call QTSession.close( ) when you’re done with QuickTime to give it a chance to clean up.

In general, this means you might want to call QTSession.open( ) as early as possible and QTSession.close( ) as late as possible. The former is easy enough to do: just put it in your application’s entry point or even in a static initializer so that it precedes main( ). On the other hand, ensuring that you call QTSession.close( ) gracefully is trickier, because your user could quit your application with a menu item you provide, a Ctrl-C, a Cmd-Q (on Mac), or (heaven forbid) a kill -9 your-pid from the command line. Ideally, you’d like to have a fighting chance of properly closing QuickTime in as many cases as possible.

How do I do that?

One way to close QuickTime late is to put QTSession.close() in a Java shutdown hook, which will get called as the JVM goes away. There are no guarantees, but it’s better than nothing.

Note

You can also run this example with the provided ant run-ch01-qtversioncheck task.

You can use the class in Example 1-4 as a general-purpose session handler for QTJ. It is presented here so that none of the other examples in the book will need to explicitly handle opening or closing the QTSession ...