//获取虚拟按键的高度
    public static int getNavigationBarHeight(Context context) {
        int result = 0;
        if (hasNavBar(context)) {
            Resources res = context.getResources();
            int resourceId = res.getIdentifier("navigation_bar_height", "dimen", "android");
            if (resourceId > 0) {
                result = res.getDimensionPixelSize(resourceId);
            }
        }
        return result;
    }

    /**
     * 检查是否存在虚拟按键栏
*
     * @param context
* @return
*/
@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    public static boolean hasNavBar(Context context) {
        Resources res = context.getResources();
        int resourceId = res.getIdentifier("config_showNavigationBar", "bool", "android");
        if (resourceId != 0) {
            boolean hasNav = res.getBoolean(resourceId);
            // check override flag
String sNavBarOverride = getNavBarOverride();
            if ("1".equals(sNavBarOverride)) {
                hasNav = false;
            } else if ("0".equals(sNavBarOverride)) {
                hasNav = true;
            }
            return hasNav;
        } else { // fallback
return !ViewConfiguration.get(context).hasPermanentMenuKey();
        }
    }

    /**
     * 判断虚拟按键栏是否重写
*
     * @return
*/
private static String getNavBarOverride() {
        String sNavBarOverride = null;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            try {
                Class c = Class.forName("android.os.SystemProperties");
                Method m = c.getDeclaredMethod("get", String.class);
                m.setAccessible(true);
                sNavBarOverride = (String) m.invoke(null, "qemu.hw.mainkeys");
            } catch (Throwable e) {
            }
        }
        return sNavBarOverride;
    }

}