private void initGesture() {
	final GestureLibrary gestureLibrary = GestureLibraries.fromRawResource(
			context, R.raw.gestures);
	gestureLibrary.load();

	gestureOverlayView
			.addOnGesturePerformedListener(new OnGesturePerformedListener() {

				@Override
				public void onGesturePerformed(GestureOverlayView overlay,
						Gesture gesture) {
					ArrayList<Prediction> arrayList = gestureLibrary
							.recognize(gesture);

					Prediction prediction = arrayList.get(0);
					if (prediction.score >= 3.0) {
						if (prediction.name.equals("back")) {
							Toast.makeText(context, "退出",
									Toast.LENGTH_SHORT).show();
							finish();
						}

					} else {
						Toast.makeText(context, "手势不存在", Toast.LENGTH_SHORT)
								.show();
					}

				}
			});

}