如何在 Flutter 中制作 AlertDialog？

一键式

showAlertDialog(BuildContext context) {

  // set up the button
  Widget okButton = TextButton(
    child: Text("OK"),
    onPressed: () { },
  );

  // set up the AlertDialog
  AlertDialog alert = AlertDialog(
    title: Text("My title"),
    content: Text("This is my message."),
    actions: [
      okButton,
    ],
  );

  // show the dialog
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

两个按钮

showAlertDialog(BuildContext context) {

  // set up the buttons
  Widget cancelButton = TextButton(
    child: Text("Cancel"),
    onPressed:  () {},
  );
  Widget continueButton = TextButton(
    child: Text("Continue"),
    onPressed:  () {},
  );

  // set up the AlertDialog
  AlertDialog alert = AlertDialog(
    title: Text("AlertDialog"),
    content: Text("Would you like to continue learning how to use Flutter alerts?"),
    actions: [
      cancelButton,
      continueButton,
    ],
  );

  // show the dialog
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

三个按钮

showAlertDialog(BuildContext context) {

  // set up the buttons
  Widget remindButton = TextButton(
    child: Text("Remind me later"),
    onPressed:  () {},
  );
  Widget cancelButton = TextButton(
    child: Text("Cancel"),
    onPressed:  () {},
  );
  Widget launchButton = TextButton(
    child: Text("Launch missile"),
    onPressed:  () {},
  );

  // set up the AlertDialog
  AlertDialog alert = AlertDialog(
    title: Text("Notice"),
    content: Text("Launching this missile will destroy the entire universe. Is this what you intended to do?"),
    actions: [
      remindButton,
      cancelButton,
      launchButton,
    ],
  );

  // show the dialog
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

处理按钮按下

上述示例中按钮的 onPressed 回调为空，但您可以添加如下内容：

Widget launchButton = TextButton(
  child: Text("Launch missile"),
  onPressed:  () {
    Navigator.of(context).pop(); // dismiss dialog
    launchMissile();
  },
);

如果您进行回调 null，则该按钮将被禁用。

onPressed: null,

https://i.stack.imgur.com/QttPd.png

补充代码

以下是 main.dart 的代码，以防您无法运行上述函数。

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter',
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter'),
        ),
        body: MyLayout()),
    );
  }
}

class MyLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: ElevatedButton(
        child: Text('Show alert'),
        onPressed: () {
          showAlertDialog(context);
        },
      ),
    );
  }
}

// replace this function with the examples above
showAlertDialog(BuildContext context) { ... }

---

我使用了类似的方法，但我想

将对话框代码作为小部件保存在单独的文件中，以便我可以重复使用它。显示对话框时模糊背景。

https://i.stack.imgur.com/hHwUq.jpg

代码：1. alertDialog_widget.dart

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


class BlurryDialog extends StatelessWidget {

  String title;
  String content;
  VoidCallback continueCallBack;

  BlurryDialog(this.title, this.content, this.continueCallBack);
  TextStyle textStyle = TextStyle (color: Colors.black);

  @override
  Widget build(BuildContext context) {
    return BackdropFilter(
      filter: ImageFilter.blur(sigmaX: 6, sigmaY: 6),
      child:  AlertDialog(
      title: new Text(title,style: textStyle,),
      content: new Text(content, style: textStyle,),
      actions: <Widget>[
        new FlatButton(
          child: new Text("Continue"),
           onPressed: () {
            continueCallBack();
          },
        ),
        new FlatButton(
          child: Text("Cancel"),
          onPressed: () {
            Navigator.of(context).pop();
          },
        ),
      ],
      ));
  }
}

您可以通过创建一个新方法来在 main（或任何您想要的地方）中调用它，例如：

 _showDialog(BuildContext context)
{

  VoidCallback continueCallBack = () => {
 Navigator.of(context).pop(),
    // code on continue comes here

  };
  BlurryDialog  alert = BlurryDialog("Abort","Are you sure you want to abort this operation?",continueCallBack);


  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

---

您可以使用此代码片段来创建两个按钮的警报框，

import 'package:flutter/material.dart';

class BaseAlertDialog extends StatelessWidget {

  //When creating please recheck 'context' if there is an error!

  Color _color = Color.fromARGB(220, 117, 218 ,255);

  String _title;
  String _content;
  String _yes;
  String _no;
  Function _yesOnPressed;
  Function _noOnPressed;

  BaseAlertDialog({String title, String content, Function yesOnPressed, Function noOnPressed, String yes = "Yes", String no = "No"}){
    this._title = title;
    this._content = content;
    this._yesOnPressed = yesOnPressed;
    this._noOnPressed = noOnPressed;
    this._yes = yes;
    this._no = no;
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: new Text(this._title),
      content: new Text(this._content),
      backgroundColor: this._color,
      shape:
          RoundedRectangleBorder(borderRadius: new BorderRadius.circular(15)),
      actions: <Widget>[
        new FlatButton(
          child: new Text(this._yes),
          textColor: Colors.greenAccent,
          onPressed: () {
            this._yesOnPressed();
          },
        ),
        new FlatButton(
          child: Text(this._no),
          textColor: Colors.redAccent,
          onPressed: () {
            this._noOnPressed();
          },
        ),
      ],
    );
  }
}

要显示对话框，您可以有一个在导入 BaseAlertDialog 类后调用它的方法 NB

_confirmRegister() {
var baseDialog = BaseAlertDialog(
    title: "Confirm Registration",
    content: "I Agree that the information provided is correct",
    yesOnPressed: () {},
    noOnPressed: () {},
    yes: "Agree",
    no: "Cancel");
showDialog(context: context, builder: (BuildContext context) => baseDialog);
}

输出将是这样的

https://i.stack.imgur.com/v4CzM.png

---

这是一个较短但完整的代码。

如果您需要一个只有一个按钮的对话框：

await showDialog(
      context: context,
      builder: (context) => new AlertDialog(
        title: new Text('Message'),
        content: Text(
                'Your file is saved.'),
        actions: <Widget>[
          new FlatButton(
            onPressed: () {
              Navigator.of(context, rootNavigator: true)
                  .pop(); // dismisses only the dialog and returns nothing
            },
            child: new Text('OK'),
          ),
        ],
      ),
    );

如果您需要带有是/否按钮的对话框：

onPressed: () async {
bool result = await showDialog(
  context: context,
  builder: (context) {
    return AlertDialog(
      title: Text('Confirmation'),
      content: Text('Do you want to save?'),
      actions: <Widget>[
        new FlatButton(
          onPressed: () {
            Navigator.of(context, rootNavigator: true)
                .pop(false); // dismisses only the dialog and returns false
          },
          child: Text('No'),
        ),
        FlatButton(
          onPressed: () {
            Navigator.of(context, rootNavigator: true)
                .pop(true); // dismisses only the dialog and returns true
          },
          child: Text('Yes'),
        ),
      ],
    );
  },
);

if (result) {
  if (missingvalue) {
    Scaffold.of(context).showSnackBar(new SnackBar(
      content: new Text('Missing Value'),
    ));
  } else {
    saveObject();
    Navigator.of(context).pop(_myObject); // dismisses the entire widget
  }
} else {
  Navigator.of(context).pop(_myObject); // dismisses the entire widget
}
}

---

只需使用此自定义对话框类，您不需要将其保留或使其为空，因此您可以轻松进行此自定义。

import 'package:flutter/material.dart';

class CustomAlertDialog extends StatelessWidget {
  final Color bgColor;
  final String title;
  final String message;
  final String positiveBtnText;
  final String negativeBtnText;
  final Function onPostivePressed;
  final Function onNegativePressed;
  final double circularBorderRadius;

  CustomAlertDialog({
    this.title,
    this.message,
    this.circularBorderRadius = 15.0,
    this.bgColor = Colors.white,
    this.positiveBtnText,
    this.negativeBtnText,
    this.onPostivePressed,
    this.onNegativePressed,
  })  : assert(bgColor != null),
        assert(circularBorderRadius != null);

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: title != null ? Text(title) : null,
      content: message != null ? Text(message) : null,
      backgroundColor: bgColor,
      shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(circularBorderRadius)),
      actions: <Widget>[
        negativeBtnText != null
            ? FlatButton(
                child: Text(negativeBtnText),
                textColor: Theme.of(context).accentColor,
                onPressed: () {
                  Navigator.of(context).pop();
                  if (onNegativePressed != null) {
                    onNegativePressed();
                  }
                },
              )
            : null,
        positiveBtnText != null
            ? FlatButton(
                child: Text(positiveBtnText),
                textColor: Theme.of(context).accentColor,
                onPressed: () {
                  if (onPostivePressed != null) {
                    onPostivePressed();
                  }
                },
              )
            : null,
      ],
    );
  }
}

用法：

var dialog = CustomAlertDialog(
  title: "Logout",
  message: "Are you sure, do you want to logout?",
  onPostivePressed: () {},
  positiveBtnText: 'Yes',
  negativeBtnText: 'No');
showDialog(
  context: context,
  builder: (BuildContext context) => dialog);

输出：

https://i.stack.imgur.com/ONs6z.png

---

或者您可以为此使用 RFlutter Alert 库。它易于定制且易于使用。它的默认样式包括圆角，您可以根据需要添加按钮。

基本警报：

Alert(context: context, title: "RFLUTTER", desc: "Flutter is awesome.").show();

按钮警报：

Alert(
    context: context,
    type: AlertType.error,
    title: "RFLUTTER ALERT",
    desc: "Flutter is more awesome with RFlutter Alert.",
    buttons: [
    DialogButton(
        child: Text(
        "COOL",
        style: TextStyle(color: Colors.white, fontSize: 20),
        ),
        onPressed: () => Navigator.pop(context),
        width: 120,
    )
    ],
).show();

您还可以定义 generic alert styles。

*我是 RFlutter Alert 的开发者之一。

---

如果您想要漂亮且响应迅速的警报对话框，那么您可以使用颤振包，例如

rflutter 警报，花式对话框，丰富的警报，甜蜜的警报对话框，简单的对话和简单的警报

这些警报外观漂亮且反应灵敏。其中 rflutter alert 是最好的。目前我正在为我的应用程序使用 rflutter alert。

---

showAlertDialog(BuildContext context, String message, String heading,
      String buttonAcceptTitle, String buttonCancelTitle) {
    // set up the buttons
    Widget cancelButton = FlatButton(
      child: Text(buttonCancelTitle),
      onPressed: () {},
    );
    Widget continueButton = FlatButton(
      child: Text(buttonAcceptTitle),
      onPressed: () {

      },
    );

    // set up the AlertDialog
    AlertDialog alert = AlertDialog(
      title: Text(heading),
      content: Text(message),
      actions: [
        cancelButton,
        continueButton,
      ],
    );

    // show the dialog
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return alert;
      },
    );
  }

称为：

showAlertDialog(context, 'Are you sure you want to delete?', "AppName" , "Ok", "Cancel");

---

警报对话框的最小代码

showDialog(
  context: context,
  builder: (_) => AlertDialog(
    title: Text('Title'),
    content: Text(
      'Content widget',
    ),
  ),
);

---

查看 Flutter Dropdown Banner 可轻松提醒用户注意事件并迅速采取行动，而无需管理呈现、延迟和关闭组件的复杂性。

要设置它：

import 'packages:dropdown_banner/dropdown_banner.dart';
...
class MainApp extends StatelessWidget {
  ...
  @override
  Widget build(BuildContext context) {
    final navigatorKey = GlobalKey<NavigatorState>();
    ...
    return MaterialApp(
        ...
        home: DropdownBanner(
          child: Scaffold(...),
          navigatorKey: navigatorKey,
        ),
    );
  }
}

要使用它：

import 'packages:dropdown_banner/dropdown_banner.dart';
...
class SomeClass {
  ...
  void doSomethingThenFail() {
    DropdownBanner.showBanner(
      text: 'Failed to complete network request',
      color: Colors.red,
      textStyle: TextStyle(color: Colors.white),
    );
  }
}

这里

---

显示对话框的另一个简单选项是使用 stacked_services 包

 _dialogService.showDialog(
      title: "Title",
      description: "Dialog message Tex",
         );
     });

---

此代码有效并演示了如何获取用户按下的按钮值：

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const Center(
          child: MyStatelessWidget(),
        ),
      ),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
  const MyStatelessWidget({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        // set up the buttons
        Widget cancelButton = TextButton(
          child: Text("Cancel"),
          onPressed: () => Navigator.pop(context, 'Cancel'),
        );
        Widget continueButton = TextButton(
          child: Text("Ok"),
          onPressed: () => Navigator.pop(context, 'Ok'),
        );
        showDialog<String>(
          context: context,
          builder: (BuildContext context) => AlertDialog(
            title: const Text('AlertDialog Title'),
            content: const Text('AlertDialog description'),
            actions: <Widget>[
              cancelButton,
              continueButton,
            ],
          ),
        ).then((value) => print(value));
      },
      child: const Text('Show Dialog'),
    );
  }
}

https://i.stack.imgur.com/psk0n.jpg

https://i.stack.imgur.com/WAst9l.jpg

---