Android判断NavigationBar是否显示的方法（获取屏幕真实的高度）

public boolean isNavigationBarShow(){
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
    Display display = getWindowManager().getDefaultDisplay();
    Point size = new Point();
    Point realSize = new Point();
    display.getSize(size);
    display.getRealSize(realSize);
    return realSize.y!=size.y;
  }else {
    boolean menu = ViewConfiguration.get(this).hasPermanentMenuKey();
    boolean back = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);
    if(menu || back) {
      return false;
    }else {
      return true;
    }
  }
}
public static int getNavigationBarHeight(Activity activity) {
  if (!isNavigationBarShow(activity)){
    return 0;
  }
  Resources resources = activity.getResources();
  int resourceId = resources.getIdentifier("navigation_bar_height",
      "dimen", "android");
  //获取NavigationBar的高度
  int height = resources.getDimensionPixelSize(resourceId);
  return height;
}
public static int getSceenHeight(Activity activity) {
  return activity.getWindowManager().getDefaultDisplay().getHeight()+getNavigationBarHeight(activity);
}