问题是，当您的应用程序进入后台时， MainActivity 将调用 onPause ，并且该方法中的代码将调用 mBeaconManager.unbind（this）; 方法，可以有效地停止信标的测距。

The problem is that when your app goes to the background, the MainActivity will call onPause, and the code inside that method calls the mBeaconManager.unbind(this); method, which effectively stops beacon ranging.

如果要继续测距在后台，最简单的操作是移动以下两行：

If you want ranging to continue in the background, the easiest thing to do is move the following two lines:

mBeaconManager.startRangingBeaconsInRegion(new Region("treewalker", null, null, null));
mBeaconManager.addRangeNotifier(this);

到 BeaconApp 类' didDetermineStateForRegion 方法。您还需要将 didRangeBeaconsInRegion 和 showNotification 方法也移到那里。

to the BeaconApp class' didDetermineStateForRegion method. You'll also need to move the didRangeBeaconsInRegion and showNotification methods there, too.