GetX实现底部菜单切换

学习了Flutter两个月，看过无数大神的视频于文章，发现在状态管理与框架方面GetX的优势在于代码量少，书写逻辑利于我这样的小白用户理解。
目前在自己完成一个独立的项目，笔记将详细记录学习过程中遇到的问题与解决方法。

依赖

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.0

  #GetX
  get: ^3.24.0

  #底部菜单
  custom_navigation_bar: ^0.6.0

底部菜单交互使用了custom_navigation_bar，因为主要是理解GetX实现切换的逻辑，所以用已有的组件实现比较快。

controller

import 'package:get/get.dart';

class ApplicationController extends GetxController {
  ///当前Tap页码
  var selectedIndex = 0.obs;

  // 显示页面对应页码
  void onBottomNavigationBar(int index) {
    selectedIndex.value = index;
  }
}

view

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:get/get.dart';
import 'package:newspmbear_app/page/application/application_controller.dart';
import 'package:newspmbear_app/page/find/find_view.dart';
import 'package:newspmbear_app/page/home/home_view.dart';
import 'package:custom_navigation_bar/custom_navigation_bar.dart';
import 'package:newspmbear_app/page/my/my_view.dart';
import 'package:newspmbear_app/page/video/video_view.dart';

class ApplicationPage extends StatelessWidget {
  final ApplicationController applicationController =
      Get.put(ApplicationController());

  //底部菜单
  Widget _buildBottomNavigationBar() {
    return Obx(
      () => CustomNavigationBar(
        iconSize: 28.0,
        selectedColor: Color(0xff040307),
        strokeColor: Color(0x30040307),
        unSelectedColor: Color(0xffacacac),
        backgroundColor: Colors.white,
        items: [
          CustomNavigationBarItem(
            icon: Icon(Icons.home),
            title: Text("首页"),
          ),
          CustomNavigationBarItem(
            icon: Icon(Icons.shopping_cart),
            title: Text("视频"),
          ),
          CustomNavigationBarItem(
            icon: Icon(Icons.lightbulb_outline),
            title: Text("发现"),
          ),
          CustomNavigationBarItem(
            icon: Icon(Icons.account_circle),
            title: Text("我的"),
          ),
        ],
        //获取当前按钮数值
        currentIndex: applicationController.selectedIndex.value,
        //切换当前页面
        onTap: applicationController.onBottomNavigationBar,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    ScreenUtil.init(context,
        designSize: Size(375, 812), allowFontScaling: true);
    List<Widget> _getPageView = [
      HomePage(),
      VideoPage(),
      FindPage(),
      MyPage(),
    ];
    return Scaffold(
      // 显示对应的页面
      body: Obx(() =>
          _getPageView.elementAt(applicationController.selectedIndex.value)),
      bottomNavigationBar: _buildBottomNavigationBar(),
    );
  }
}