Question

我正在FutureBuilder屏幕上使用BottomNavigationBar。但是，每当我单击其他选项卡并返回时，FutureBuilder都会重新加载所有内容。我已经在使用AutomaticKeepAliveClientMixin，在保存 getLessons（）时遇到了麻烦，所以我不必再次加载它。有人可以帮我吗？

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<List<Lesson>>(
        future: getLessons(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.none) {
          } else if (snapshot.connectionState == ConnectionState.waiting) {
          } else {
            return Container();
          }
        });
  }

这是我的getLessons（）：

  Future<List<Lesson>> getLessons() async {
    String url = "...";
    http.Response response = await http.get(url);
    var data = json.decode(response.body);
    (...)
    return lessons;
  }

如何维护状态以免更新？

Answer 1

// Create instance variable
Future myFuture;

@override
void initState() {
  super.initState();

  // assign this variable your Future
  myFuture = getLessons();
}


@override
  Widget build(BuildContext context) {
    return FutureBuilder<List<Lesson>>(
        future: future, // use your future here
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.none) {
          } else if (snapshot.connectionState == ConnectionState.waiting) {
          } else {
            return Container();
          }
        });
  }

贷记CopsOnRoad

Answer 2

问题是我没有使用PageView来调用屏幕。我在build()外部启动了4个屏幕，并在PageView内将它们全部调用，现在可以使用了。

body: PageView(
    controller: _pageController,
    onPageChanged: (index) {
      setState(() {
        _index = index;
      });
    },
    children: [_container1, _container2, _container3, _container4],
  ),

每当更改BottomNavigationBarItem时，FutureBuilder就会重新加载

2 个答案: