TextField(
  controller: _controller,
  keyboardType: TextInputType.number,
  inputFormatters: <TextInputFormatter>[
  FilteringTextInputFormatter.allow(RegExp(r'[0.0-9.9]')),
 ])

我需要en IntegerFormField与最小/最大的控制。最大的问题是当焦点改变时，oneditingcomplete没有被调用。以下是我的解决方案:

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:vs_dart/vs_dart.dart';

class IntegerFormField extends StatefulWidget {
  final int value, min, max;
  final InputDecoration decoration;
  final ValueChanged<TextEditingController> onEditingComplete;
  IntegerFormField({@required this.value, InputDecoration decoration, onEditingComplete, int min, int max})
      : min = min ?? 0,
        max = max ?? maxIntValue,
        onEditingComplete = onEditingComplete ?? ((_) {}),
        decoration = decoration ?? InputDecoration()
  ;

  @override
  _State createState() => _State();
}

class _State extends State<IntegerFormField> {
  final TextEditingController controller = TextEditingController();

  @override
  void initState() {
    super.initState();
    controller.text = widget.value.toString();
  }

  @override
  void dispose() {
    super.dispose();
  }

  void onEditingComplete() {
    {
      try {
        if (int.parse(controller.text) < widget.min)
          controller.text = widget.min.toString();
        else if (int.parse(controller.text) > widget.max)
          controller.text = widget.max.toString();
        else
          FocusScope.of(context).unfocus();
      } catch (e) {
        controller.text = widget.value.toString();
      }
      widget.onEditingComplete(controller);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Focus(
      child: TextFormField(
        controller: controller,
        inputFormatters: [FilteringTextInputFormatter.digitsOnly],
        keyboardType: TextInputType.number,
        decoration: widget.decoration,
      ),
      onFocusChange: (value) {
        if (value)
          controller.selection = TextSelection(baseOffset: 0, extentOffset: controller.value.text.length);
        else
          onEditingComplete();
      },
    );
  }
}

U可以安装intl_phone_number_input包

dependencies:
  intl_phone_number_input: ^0.5.2+2

试试下面的代码:

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    var darkTheme = ThemeData.dark().copyWith(primaryColor: Colors.blue);

    return MaterialApp(
      title: 'Demo',
      themeMode: ThemeMode.dark,
      darkTheme: darkTheme,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(title: Text('Demo')),
        body: MyHomePage(),
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final GlobalKey<FormState> formKey = GlobalKey<FormState>();

  final TextEditingController controller = TextEditingController();
  String initialCountry = 'NG';
  PhoneNumber number = PhoneNumber(isoCode: 'NG');

  @override
  Widget build(BuildContext context) {
    return Form(
      key: formKey,
      child: Container(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            InternationalPhoneNumberInput(
              onInputChanged: (PhoneNumber number) {
                print(number.phoneNumber);
              },
              onInputValidated: (bool value) {
                print(value);
              },
              selectorConfig: SelectorConfig(
                selectorType: PhoneInputSelectorType.BOTTOM_SHEET,
                backgroundColor: Colors.black,
              ),
              ignoreBlank: false,
              autoValidateMode: AutovalidateMode.disabled,
              selectorTextStyle: TextStyle(color: Colors.black),
              initialValue: number,
              textFieldController: controller,
              inputBorder: OutlineInputBorder(),
            ),
            RaisedButton(
              onPressed: () {
                formKey.currentState.validate();
              },
              child: Text('Validate'),
            ),
            RaisedButton(
              onPressed: () {
                getPhoneNumber('+15417543010');
              },
              child: Text('Update'),
            ),
          ],
        ),
      ),
    );
  }

  void getPhoneNumber(String phoneNumber) async {
    PhoneNumber number =
        await PhoneNumber.getRegionInfoFromPhoneNumber(phoneNumber, 'US');

    setState(() {
      this.number = number;
    });
  }

  @override
  void dispose() {
    controller?.dispose();
    super.dispose();
  }
}

你可以试试这个:

TextFormField(
     keyboardType: TextInputType.number,
     decoration: InputDecoration(
              prefixIcon: Text("Enter your number: ")
     ),
     initialValue: "5",
     onSaved: (input) => _value = num.tryParse(input),
),

下面是Android上实际的手机键盘代码:

按键部分:keyboardType: TextInputType.phone，

  TextFormField(
    style: TextStyle(
      fontSize: 24
    ),
    controller: _phoneNumberController,
    keyboardType: TextInputType.phone,
    decoration: InputDecoration(
      prefixText: "+1 ",
      labelText: 'Phone number'),
    validator: (String value) {
      if (value.isEmpty) {
        return 'Phone number (+x xxx-xxx-xxxx)';
      }
      return null;
    },
  ),

TextField(
  controller: _controller,
  keyboardType: TextInputType.number,
  inputFormatters: <TextInputFormatter>[
  FilteringTextInputFormatter.allow(RegExp(r'[0.0-9.9]')),
 ])