如果你的使用情况是添加多个TextFields内你Dialog让你的主Form不会显得很拥挤，我觉得这是更好，如果你建立的东西不是更加个性化AlertDialog，并SimpleDialog为它们用于简单的活动（确认，radios..etc）。

否则，为什么要对Dialog单个使用a TextField？

当我们添加多个TextFields时，我们应该谨慎选择设计，因为其他人将与该视图交互以填充数据，在这种情况下，我更喜欢使用class
fullscreenDialog属性PageRoute。我不确定SimpleDialogFlutter 是否适合。

这是一个有关如何使用的快速示例FullScreenDialog，希望此帮助，您应该能够按照自己的方式对其进行修改：

import 'package:flutter/material.dart';


void main() {
  runApp(new MaterialApp(home: new MyApp(),));
}

class MyApp extends StatefulWidget {
  @override
  MyAppState createState() => new MyAppState();
}

class MyAppState extends State<MyApp> {
  FullScreenDialog _myDialog = new FullScreenDialog();

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(
          title: new Text("Fill this form"),
        ),
        body: new Column(
          children: <Widget>[
            new TextField(controller: new TextEditingController(
                text: "Add a single text field"),),

            new Card(child: new ListTile(
              title: new Text("Click to add your top 3 amazing skills"),
              subtitle: new Text(
                  "${_myDialog._skillOne} ${_myDialog._skillTwo} ${_myDialog
                      ._skillThree}"),
              onTap: () {
                Navigator.push(context, new MaterialPageRoute(
                  builder: (BuildContext context) => _myDialog,
                  fullscreenDialog: true,
                ));
              },
            ),
            ),
          ],
        )
    );
  }

}


class FullScreenDialog extends StatefulWidget {
  String _skillOne = "You have";
  String _skillTwo = "not Added";
  String _skillThree = "any skills yet";

  @override
  FullScreenDialogState createState() => new FullScreenDialogState();
}

class FullScreenDialogState extends State<FullScreenDialog> {
  TextEditingController _skillOneController = new TextEditingController();
  TextEditingController _skillTwoController = new TextEditingController();

  TextEditingController _skillThreeController = new TextEditingController();

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(
          title: new Text("Add your top 3 skills"),
        ),
        body: new Padding(child: new ListView(
          children: <Widget>[
            new TextField(controller: _skillOneController,),
            new TextField(controller: _skillTwoController,),
            new TextField(controller: _skillThreeController,),
            new Row(
              children: <Widget>[
                new Expanded(child: new RaisedButton(onPressed: () {
                  widget._skillThree = _skillThreeController.text;
                  widget._skillTwo = _skillTwoController.text;
                  widget._skillOne = _skillOneController.text;
                  Navigator.pop(context);
                }, child: new Text("Save"),))
              ],
            )
          ],
        ), padding: const EdgeInsets.symmetric(horizontal: 20.0),)
    );
  }


}

编辑

经过研究后，看来这是当前Flutter版本中的错误，此问题中也记录了临时修复程序。

import 'package:flutter/material.dart';

void main() {
  runApp(new MaterialApp(home: new FocusVisibilityDemo()));
}

class FocusVisibilityDemo extends StatefulWidget {
  @override
  _FocusVisibilityDemoState createState() => new _FocusVisibilityDemoState();
}


class _FocusVisibilityDemoState extends State<FocusVisibilityDemo> {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(title: new Text('Text Dialog Demo')),
      body: new Center(
        child: new RaisedButton(
          onPressed: _showDialog,
          child: new Text("Push Me"),
        ),
      ),
    );
  }

  _showDialog() async {
    await showDialog<String>(
      context: context,
      child: new _SystemPadding(child: new AlertDialog(
        contentPadding: const EdgeInsets.all(16.0),
        content: new Row(
          children: <Widget>[
            new Expanded(
              child: new TextField(
                autofocus: true,
                decoration: new InputDecoration(
                    labelText: 'Full Name', hintText: 'eg. John Smith'),
              ),
            )
          ],
        ),
        actions: <Widget>[
          new FlatButton(
              child: const Text('CANCEL'),
              onPressed: () {
                Navigator.pop(context);
              }),
          new FlatButton(
              child: const Text('OPEN'),
              onPressed: () {
                Navigator.pop(context);
              })
        ],
      ),),
    );
  }
}


class _SystemPadding extends StatelessWidget {
  final Widget child;

  _SystemPadding({Key key, this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    var mediaQuery = MediaQuery.of(context);
    return new AnimatedContainer(
        padding: mediaQuery.viewInsets,
        duration: const Duration(milliseconds: 300),
        child: child);
  }
}