问题
I have gone through
- Setting java.awt.headless=true programmatically
- http://www.oracle.com/technetwork/articles/javase/headless-136834.html and
- Some other links too.
Nowhere it is explained the benefit of using this flag.
Is it a performance benefit? If yes, is there even a rough quntization how much performance benefit there will be? (I know that answers to performance questions totally depend upon case to case, but it would be nice to know if someone reported a good benefit from doing this).
回答1:
Headless and non-headless modes are different, they have different set of features. If you only need to do some simple things like font rendering then yes, you will be able to do it in headless mode.
You can always check the guts of the JDK sources and see for yourself, what methods are dependent on non-headless mode. But in my opinion, even if the performance gain is negligible, it's best to pass java.awt.headless anyway (if you do not need "full" GUI mode).
Any vendor can use this property. You never know if they are going to do something if you have the full GUI. So, my rule of thumb is: always use java.awt.headless for the console apps and the servers. It won't harm.
回答2:
One possible benefit is that if you are invoking the application while trying to do something else in a window perhaps invoking the application multiple times, it will not disrupt your keyboard/mouse focus if the application runs in headless mode.
At least on a Mac I have had huge problems running a script which repeatedly runs a java app every few seconds while trying to edit in another window. Headless mode fixes that.
来源：https://stackoverflow.com/questions/41067235/what-is-the-benefit-of-setting-java-awt-headless-true