Flutter pageview :查找第一页和最后一页，并滑动方向

import 'package:flutter/material.dart';

class MyPage extends StatefulWidget {
  @override
  _MyPageState createState() => _MyPageState();
}

class _MyPageState extends State<MyPage> {
  final PageController _pageController = PageController();
  int _currentPage = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('PageView Demo'),
      ),
      body: PageView(
        controller: _pageController,
        onPageChanged: (index) {
          setState(() {
            _currentPage = index;
          });
          if (index == 0) {
            // 第一页的操作
          } else if (index == _pageController.pageCount - 1) {
            // 最后一页的操作
          }
        },
        children: <Widget>[
          // 页面列表
          Container(color: Colors.red),
          Container(color: Colors.green),
          Container(color: Colors.blue),
        ],
      ),
    );
  }
}