以编程方式确定Android设备是否具有菜单按钮的方法？

Question

I need to compensate for the lack of a physical (or even a "soft") menu button on Android 3 tablets. The app I'm working on generally hides the title bar for its activities, but I can't do that if I want the action bar to appear on a tablet. Is there something in the API that I can use to determine whether a device has a menu button?

If I can't find such a function, the only thing I can think of to do is to never hide the title bar on Android 3.0 and later, but that bothers me for two reasons:

1. I believe Android 3.0 (or a later API) will eventually support phones, which will probably have menu buttons
2. I would prefer not to hard code that SDK version (perhaps I could never hide the title bar for Android 3.0 and above, but then I run the risk of not hiding the title bar on phones)

Answer 1

LeffelMania has the right idea, but there is a caveat: If you target SDK 11 (3.0) and use a no-title-bar theme or override with a custom title of some sort, you will be just plain menu-less, because on Honeycomb devices with the target set to 11 the options-menu lives in the title bar itself instead of a fake menu button in the bottom status bar. So be careful there! (You can work around this by setting a lower target, or targeting style resources to v11 to use a one of the Holo themes with a titlebar in that case).

Answer 2

DEPRECATED: This answer is no longer accurate, given changes to the Android framework and design guidelines.

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Android phones are guaranteed to have a Menu button. All phones pre-Honeycomb have Menu buttons, and Honeycomb features an ever-present software button. If you use the proper callbacks that tie into the Menu button (onCreateOptionsMenu(), onOptionsItemSelected(), etc) you will be safe to receive those callbacks on any device running Android.

Answer 3

从API级别14开始， ViewConfiguration.hasPermanentMenuKey（）可用于指示是否存在永久菜单键。