强制启用

导入包：import package:flutter/services.dart;在main.dart文件

1.横向模式：

// Set landscape orientation
SystemChrome.setPreferredOrientations([
  DeviceOrientation.landscapeLeft,
  DeviceOrientation.landscapeRight,
]);

2.时尚肖像：

// Set portrait orientation
SystemChrome.setPreferredOrientations([
   DeviceOrientation.portraitDown,
   DeviceOrientation.portraitUp,
]);