Flutter在键盘的上方加一个完成按钮

有些情况下，输入框在输入键盘弹出后， 需要在键盘的上方显示一个toolbar ， 然后 toolbar 上面一个完成按钮，点完成按钮把键盘关闭。 

如图： 

直接上代码，这样写的好处是，把 TextField 给封装了， 这样使用起来更方便一些，

更多的属性，自己可以在上面扩展。 

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class KeyboardDoneInput extends StatefulWidget {final TextEditingController controller;final ValueChanged<String>? onSubmitted;const KeyboardDoneInput({Key? key,required this.controller,this.onSubmitted,}) : super(key: key);@overrideState<KeyboardDoneInput> createState() => _KeyboardDoneInputState();
}class _KeyboardDoneInputState extends State<KeyboardDoneInput> {late final FocusNode _focusNode = FocusNode();OverlayEntry? _overlayEntry;@overridevoid initState() {super.initState();_focusNode.addListener(_handleFocusChange);}void _handleFocusChange() {if (_focusNode.hasFocus) {_insertOverlay();} else {_removeOverlay();}}void _insertOverlay() {if (_overlayEntry != null) return;final overlay = Overlay.of(context);_overlayEntry = OverlayEntry(builder: (context) => Positioned(left: 0,right: 0,bottom: MediaQuery.of(context).viewInsets.bottom,child: Material(color: Colors.transparent,child: Container(padding: const EdgeInsets.symmetric(horizontal: 20),color: Colors.grey[100],child: Row(children: [const Spacer(),CupertinoButton(padding: EdgeInsets.zero,child: const Text("完成",style: TextStyle(fontSize: 16, color: Colors.black),),onPressed: () {_focusNode.unfocus();widget.onSubmitted?.call(widget.controller.text);},),],),),),),);overlay.insert(_overlayEntry!);}void _removeOverlay() {_overlayEntry?.remove();_overlayEntry = null;}@overridevoid dispose() {_focusNode.dispose();_removeOverlay();super.dispose();}@overrideWidget build(BuildContext context) {return TextField(controller: widget.controller,focusNode: _focusNode,keyboardType: TextInputType.number,textAlign: TextAlign.center,inputFormatters: [FilteringTextInputFormatter.digitsOnly],decoration: const InputDecoration(border: OutlineInputBorder(),contentPadding: EdgeInsets.symmetric(horizontal: 8, vertical: 4),),onSubmitted: widget.onSubmitted,);}
}

调用如下， 

KeyboardDoneInput(controller: _controller, onSubmitted: (value) {},
)