flutter列表页面模板：支持下拉刷新、分页加载、加载中、数据为空

import 'package:flutter/material.dart';

class Test1Page extends StatefulWidget {
  @override
  _Test1PageState createState() {
    return _Test1PageState();
  }
}

class _Test1PageState extends State {
  ScrollController _scrollController = ScrollController();
  bool isLoading = true;//是否加载中
  bool isLoadOk = false;//是否加载完成
  var list = List