对于那些正在寻找能在路线变化中幸存下来的吐司的人来说，SnackBar可能不是最好的选择。

让我们来看看Overlay。

您可以使用飘动吐司包装。为此，将其添加到pubspec中。Yaml文件如下:

dependencies:
  fluttertoast: ^8.0.8

然后在需要吐司的.dart文件中导入这个包并编写代码。

例如，参考以下代码:

import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';

class ToastExample extends StatefulWidget {
    @override
    _ToastExampleState createState() {
      return _ToastExampleState();
    }
  }

  class _ToastExampleState extends State {
    void showToast() {
      Fluttertoast.showToast(
          msg: 'This is flutterToast example', // Message
          toastLength: Toast.LENGTH_SHORT,    // toast length
          gravity: ToastGravity.CENTER,      // position
          timeInSecForIos: 1,               // duaration
          backgroundColor: Colors.red,     // background color
          textColor: Colors.white         // text color
      );
    }

    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Toast Tutorial',
        home: Scaffold(
            appBar: AppBar(
              title: Text('Toast Tutorial'),
            ),
            body: Padding(
              padding: EdgeInsets.all(15.0),
              child: Center(
                child: RaisedButton(
                  child: Text('Show Toast'),
                  onPressed: showToast,
                ),
              ),
            )
        ),
      );
    }
  }

  void main() => runApp(ToastExample());

更新:Scaffold.of(上下文)。showSnackBar在Flutter 2.0.0中已弃用(稳定)

你可以使用ScaffoldMessenger.of(context)访问父类ScaffoldMessengerState。

然后做一些类似的事情

ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      content: Text("Sending Message"),
    ));

零食条是材料设计的官方“吐司”。看到间小吃店。

下面是一个完整的例子:

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: Home(),
    );
  }
}

class Home extends StatelessWidget {
  const Home({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Snack bar'),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: () => _showToast(context),
          child: const Text('Show toast'),
        ),
      ),
    );
  }

  void _showToast(BuildContext context) {
    final scaffold = ScaffoldMessenger.of(context);
    scaffold.showSnackBar(
      SnackBar(
        content: const Text('Added to favorite'),
        action: SnackBarAction(label: 'UNDO', onPressed: scaffold.hideCurrentSnackBar),
      ),
    );
  }
}

这很简单:

我们只需要安装颤动吐司包。 请参考以下文档: https://pub.dev/packages/fluttertoast

在安装选项卡，你会得到依赖，你必须把它粘贴到pubspec。Yaml文件然后安装。

在此之后，只需导入包:

import 'package:fluttertoast/fluttertoast.dart';

类似于上面的一行。

然后通过使用FlutterToast类你可以使用你的FlutterToast。

你做完了! !

在这里买颤振吐司包

将这个包添加到文件pubspec.yaml中的项目依赖项中。

然后当你想要吐司显示时，就像点击一个按钮:

Toast.show("Toast plugin app", context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM);

正如Darky指出的那样，SnackBar绝对是正确的类。

关于showSnackBar的一个棘手的事情是到达Scaffold state，如果你试图在构建方法中调用showSnackBar。

您可能会看到这样的错误，其中包括一些解释如何解决问题的文本。

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following assertion was thrown while handling a gesture:
Scaffold.of() called with a context that does not contain a Scaffold.
No Scaffold ancestor could be found starting from the context that was passed to Scaffold.of(). This
usually happens when the context provided is from the same StatefulWidget as that whose build
function actually creates the Scaffold widget being sought.
There are several ways to avoid this problem. The simplest is to use a Builder to get a context that
is "under" the Scaffold. For an example of this, please see the documentation for Scaffold.of():
  https://docs.flutter.io/flutter/material/Scaffold/of.html
A more efficient solution is to split your build function into several widgets. This introduces a
new context from which you can obtain the Scaffold. In this solution, you would have an outer widget
that creates the Scaffold populated by instances of your new inner widgets, and then in these inner
widgets you would use Scaffold.of().
A less elegant but more expedient solution is assign a GlobalKey to the Scaffold, then use the
key.currentState property to obtain the ScaffoldState rather than using the Scaffold.of() function.
The context used was:
  MyHomePage
When the exception was thrown, this was the stack:
#0      Scaffold.of (package:flutter/src/material/scaffold.dart:444:5)
#1      MyHomePage.build.<anonymous closure> (/Users/jackson/Library/Developer/CoreSimulator/Devices/7072C907-DBAD-44FE-8F40-0257442C51D9/data/Containers/Data/Application/77FEC1A4-1453-442C-8208-96E0323DEFB2/tmp/so_scratch2Tkq9Jb/so_scratch2/lib/main.dart:23:24)
#2      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:323:14)
#3      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:375:30)
#4      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
#5      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:149:9)
#6      TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:119:7)
#7      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
#8      BindingBase&SchedulerBinding&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:147:20)
#9      BindingBase&SchedulerBinding&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
#10     BindingBase&SchedulerBinding&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
#11     BindingBase&SchedulerBinding&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
#12     BindingBase&SchedulerBinding&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
#13     _invoke1 (file:///b/build/slave/Mac_Engine/build/src/flutter/lib/ui/hooks.dart:100)
#14     _dispatchPointerDataPacket (file:///b/build/slave/Mac_Engine/build/src/flutter/lib/ui/hooks.dart:58)
Handler: onTap
Recognizer:
  TapGestureRecognizer#69dbc(debugOwner: GestureDetector, state: ready)
════════════════════════════════════════════════════════════════════════════════════════════════════

你可以将GlobalKey传递给你的Scaffold构造函数:

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final key = new GlobalKey<ScaffoldState>();
    return new Scaffold(
      key: key,
      floatingActionButton: new Builder(
        builder: (BuildContext context) {
          return new FloatingActionButton(
            onPressed: () {
              key.currentState.showSnackBar(new SnackBar(
                content: new Text("Sending Message"),
              ));
            },
            tooltip: 'Increment',
            child: new Icon(Icons.add),
          );
        }
      ),
    );
  }
}

或者你可以使用一个Builder来创建一个BuildContext，它是Scaffold的子对象。

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      floatingActionButton: new Builder(
        builder: (BuildContext context) {
          return new FloatingActionButton(
            onPressed: () {
              Scaffold.of(context).showSnackBar(new SnackBar(
                content: new Text("Sending Message"),
              ));
            },
            tooltip: 'Increment',
            child: new Icon(Icons.add),
          );
        }
      ),
    );
  }
}

最后，您可以将小部件分成多个类，这是最佳的长期方法。