Flutter 实现下拉刷新上拉加载的示例代码

dependencies:
 pull_to_refresh: ^1.5.7

import 'package:pull_to_refresh/pull_to_refresh.dart';

class _MyHomePageState extends State<MyHomePage  {
 List<String  items = ["1", "2", "3", "4", "5", "6", "7", "8"];
 RefreshController _refreshController =
 RefreshController(initialRefresh: false);

 void _onRefresh() async {
  // monitor network fetch
  await Future.delayed(Duration(milliseconds: 1000));
  // if failed,use refreshFailed()
  _refreshController.refreshCompleted();
 }

 void _onLoading() async {
  // monitor network fetch
  await Future.delayed(Duration(milliseconds: 1000));
  // if failed,use loadFailed(),if no data return,use LoadNodata()
  items.add((items.length + 1).toString());
  if (mounted) setState(() {});
  _refreshController.loadComplete();
 }

 @override
 Widget build(BuildContext context) {
  return Scaffold(
   body: SmartRefresher(
    enablePullDown: true,
    enablePullUp: true,
    header: WaterDropHeader(),
    footer: CustomFooter(
     builder: (BuildContext context, LoadStatus mode) {
      Widget body;
      if (mode == LoadStatus.idle) {
       body = Text("pull up load");
      } else if (mode == LoadStatus.loading) {
       body = CircularProgressIndicator();
      } else if (mode == LoadStatus.failed) {
       body = Text("Load Failed!Click retry!");
      } else if (mode == LoadStatus.canLoading) {
       body = Text("release to load more");
      } else {
       body = Text("No more Data");
      }
      return Container(
       height: 55.0,
       child: Center(child: body),
      );
     },
    ),
    controller: _refreshController,
    onRefresh: _onRefresh,
    onLoading: _onLoading,
    child: ListView.builder(
     itemBuilder: (c, i) =  Card(child: Center(child: Text(items[i]))),
     itemExtent: 100.0,
     itemCount: items.length,
    ),
   ),
  );
 }
}