对于Flutter 1.17.3(截至2020年6月的稳定通道)，请使用

FocusManager.instance.primaryFocus.unfocus();

取消键盘(1.7.8+热修复。2和以上)只需调用下面的方法:

FocusScope.of(context).unfocus();

一旦FocusScope.of(context).unfocus()方法在解散键盘之前检查是否有焦点，就不需要检查它了。但如果你需要它，只需调用另一个上下文方法:FocusScope.of(context).hasPrimaryFocus

尝试使用TextEditingController。 一开始，

    final myController = TextEditingController();
     @override
  void dispose() {
    // Clean up the controller when the widget is disposed.
    myController.dispose();
    super.dispose();
  }

在新闻发布会上，

onPressed: () {
            myController.clear();}

这将取消键盘。

你可以用"GestureDetector"来包装你的小部件，然后将"FocusScope.of(context).unfocus()"赋值给它的onTap函数

GestureDetector(
 onTap: () => FocusScope.of(context).unfocus(),
 child: child,
);

您可以使用FocusNode类中的unfocus()方法。

import 'package:flutter/material.dart';

class MyHomePage extends StatefulWidget {
  MyHomePageState createState() => new MyHomePageState();
}

class MyHomePageState extends State<MyHomePage> {
  TextEditingController _controller = new TextEditingController();
  FocusNode _focusNode = new FocusNode(); //1 - declare and initialize variable

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(),
      floatingActionButton: new FloatingActionButton(
        child: new Icon(Icons.send),
        onPressed: () {
            _focusNode.unfocus(); //3 - call this method here
        },
      ),
      body: new Container(
        alignment: FractionalOffset.center,
        padding: new EdgeInsets.all(20.0),
        child: new TextFormField(
          controller: _controller,
          focusNode: _focusNode, //2 - assign it to your TextFormField
          decoration: new InputDecoration(labelText: 'Example Text'),
        ),
      ),
    );
  }
}

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

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

你也可以为你的文本域声明一个focusNode，当你完成时，你可以在那个focusNode上调用unfocus方法 然后处理它

class MyHomePage extends StatefulWidget {
  MyHomePageState createState() => new MyHomePageState();
}

class MyHomePageState extends State<MyHomePage> {
  TextEditingController _controller = new TextEditingController();

/// declare focus
  final FocusNode _titleFocus = FocusNode();

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

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(),
      floatingActionButton: new FloatingActionButton(
        child: new Icon(Icons.send),
        onPressed: () {
          setState(() {
            // send message
            // dismiss on screen keyboard here

            _titleFocus.unfocus();
            _controller.clear();
          });
        },
      ),
      body: new Container(
        alignment: FractionalOffset.center,
        padding: new EdgeInsets.all(20.0),
        child: new TextFormField(
          controller: _controller,
          focusNode: _titleFocus,
          decoration: new InputDecoration(labelText: 'Example Text'),
        ),
      ),
    );
  }
}