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());
}

总之，这是Flutter 1.17的工作解决方案:

像这样包装你的Widget:

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

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'),
        ),
      ),
    );
  }
}

如果你使用CustomScrollView，只要放，

keyboardDismissBehavior: ScrollViewKeyboardDismissBehavior.onDrag,

注意:这个答案已经过时了。有关Flutter的新版本，请参阅答案。

你可以通过把TextFormField的焦点拿走，并把它给一个未使用的FocusNode来解散键盘:

FocusScope.of(context).requestFocus(FocusNode());

对于Flutter版本2或最新版本:

由于颤振2零安全，这是最好的方法:

FocusManager.instance.primaryFocus?.unfocus();

注意:使用旧的方法会导致一些问题，如保持重建状态;

对于颤动版本< 2:

自Flutter v1.7.8+热修复。2、要走的路是:

FocusScope.of(context).unfocus();

评论一下PR:

现在#31909 (be75fb3)已经着陆，您应该使用 FocusScope.of(context).unfocus()代替 FocusScope.of(context).requestFocus(FocusNode())，因为FocusNodes ChangeNotifiers，并且应该正确地处理。

- >不使用q r e̶̶̶̶̶u e̶s t F c o̶̶̶̶̶u s̶̶(F c o̶̶̶̶̶u s e N o d̶̶̶̶̶̶̶了。

 F̶o̶c̶u̶s̶S̶c̶o̶p̶e̶.̶o̶f̶(̶c̶o̶n̶t̶e̶x̶t̶)̶.̶r̶e̶q̶u̶e̶s̶t̶F̶o̶c̶u̶s̶(̶F̶o̶c̶u̶s̶N̶o̶d̶e̶(̶)̶)̶;̶

在flutter文档中阅读有关FocusScope类的更多信息。