一：首先判断机型是属于那种：

//小米和华为做了两种兼容判断：需要权限的情况下，无法读取配置，只能用反射
public final class OSHelper {
 public static final String SYS_EMUI = "sys_emui";
 public static final String SYS_MIUI = "sys_miui";
 public static final String SYS_FLYME = "sys_flyme";
 private static final String KEY_MIUI_VERSION_CODE = "ro.miui.ui.version.code";
 private static final String KEY_MIUI_VERSION_NAME = "ro.miui.ui.version.name";
 private static final String KEY_MIUI_INTERNAL_STORAGE = "ro.miui.internal.storage";
 private static final String KEY_EMUI_API_LEVEL = "ro.build.hw_emui_api_level";
 private static final String KEY_EMUI_VERSION = "ro.build.version.emui";
 private static final String KEY_EMUI_CONFIG_HW_SYS_VERSION = "ro.confg.hw_systemversion";

 public static boolean isFlyme() {
     try {
         final Method method = Build.class.getMethod("hasSmartBar");
         return method != null;
     } catch (final Exception e) {
         return false;
     }
 }

 public static boolean isEMUI() {
     return TextUtils.equals(getSystem(), SYS_EMUI);
 }

 public static boolean isMIUI() {
     return TextUtils.equals(getSystem(), SYS_MIUI);
 }

 private static String getSystem() {
     String SYS = "";
     if (Build.VERSION.SDK_INT > Build.VERSION_CODES.N_MR1) {
         if (!TextUtils.isEmpty(getSystemProperty(KEY_MIUI_VERSION_CODE, ""))
                 || !TextUtils.isEmpty(getSystemProperty(KEY_MIUI_VERSION_NAME, ""))
                 || !TextUtils.isEmpty(getSystemProperty(KEY_MIUI_INTERNAL_STORAGE, ""))) {
             SYS = SYS_MIUI;//小米
         } else if (!TextUtils.isEmpty(getSystemProperty(KEY_EMUI_API_LEVEL, ""))
                 || !TextUtils.isEmpty(getSystemProperty(KEY_EMUI_VERSION, ""))
                 || !TextUtils.isEmpty(getSystemProperty(KEY_EMUI_CONFIG_HW_SYS_VERSION, ""))) {
             SYS = SYS_EMUI;//华为
         }
         return SYS;
     } else {
         try {
             Properties prop = new Properties();
             prop.load(new FileInputStream(new File(Environment.getRootDirectory(), "build.prop")));
             if (prop.getProperty(KEY_MIUI_VERSION_CODE, null) != null
                     || prop.getProperty(KEY_MIUI_VERSION_NAME, null) != null
                     || prop.getProperty(KEY_MIUI_INTERNAL_STORAGE, null) != null) {
                 SYS = SYS_MIUI;//小米
             } else if (prop.getProperty(KEY_EMUI_API_LEVEL, null) != null
                     || prop.getProperty(KEY_EMUI_VERSION, null) != null
                     || prop.getProperty(KEY_EMUI_CONFIG_HW_SYS_VERSION, null) != null) {
                 SYS = SYS_EMUI;//华为
             }
         } catch (IOException e) {
             e.printStackTrace();
             return SYS;
         } finally {
             return SYS;
         }
     }
 }

 private static String getSystemProperty(String key, String defaultValue) {
     try {
         Class<?> clz = Class.forName("android.os.SystemProperties");
         Method get = clz.getMethod("get", String.class, String.class);
         return (String) get.invoke(clz, key, defaultValue);
     } catch (Exception e) {
     }
     return defaultValue;
 }

}

二:根据不同类型获取是否有Navigator

MIUI版本是根据小米提供的方法获取判断，已测可以
其它版本的根据app屏幕和实际屏幕进行对比判断是否存在，华为的，模拟器已测是可以

    //判断是否存在NavigationBar
    public static boolean checkDeviceHasNavigationBar(Context context) {

        if (context != null) {
            if (context instanceof Activity) {

                if (OSHelper.isMIUI()) {
                    boolean force_fsg_nav_bar = Settings.Global.getInt(context.getContentResolver(), "force_fsg_nav_bar", 0) != 0;
                    //true 是手势，默认是 false
                    return !force_fsg_nav_bar;//是否 有虚拟键盘
                }

                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
                    Display display = ((Activity) context).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(context).hasPermanentMenuKey();
                    boolean back = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);
                    return !menu && !back;
                }
            } else {
                return false;
            }

        } else {
            return false;
        }
    }