TextField

TextFiled 是一个输入Widget，属性如下：

this.controller,//这个是传输数据用的
this.focusNode,
this.decoration = const InputDecoration(),这个是UI设置用的
TextInputType keyboardType,这个可以设置输入键盘是数字还是字符；
this.textInputAction,
this.textCapitalization = TextCapitalization.none,
this.style,
this.strutStyle,
this.textAlign = TextAlign.start,
this.textDirection,
this.autofocus = false,
this.obscureText = false,
this.autocorrect = true,
this.maxLines = 1,
this.minLines,
this.expands = false,
this.maxLength,
this.maxLengthEnforced = true,
this.onChanged, 这个是回调函数
this.onEditingComplete,
this.onSubmitted,
this.inputFormatters,
this.enabled,
this.cursorWidth = 2.0,
this.cursorRadius,
this.cursorColor,
this.keyboardAppearance,
this.scrollPadding = const EdgeInsets.all(20.0),
this.dragStartBehavior = DragStartBehavior.start,
this.enableInteractiveSelection,
this.onTap,
this.buildCounter,

下面是一个完整的示例：
import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: ExampleWidget(),
      ),
    );
  }
}
/// Opens an [AlertDialog] showing what the user typed.
class ExampleWidget extends StatefulWidget {
  @override
  _ExampleWidgetState createState() => new _ExampleWidgetState();
}

class _ExampleWidgetState extends State<ExampleWidget> {
  final TextEditingController _controller = TextEditingController();
  @override
  Widget build(BuildContext context) {
    return  Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        new TextField(
          controller: _controller,
          decoration: InputDecoration(
            contentPadding: EdgeInsets.all(10.0),
            labelText:'Be noticed to write something down',
            hintText: 'Type something',
          ),
          onChanged: (text){setState(() {
            print(text);
          });},
        ),
        new RaisedButton(
          onPressed: () {
            showDialog(
              context: context,
              builder: (context){
                return AlertDialog(
                  title:Text('What you typed'),
                  content:Text(_controller.text),
                );
              }
            );
          },
          child: new Text('DONE'),
        ),
      ],
    );
  }
}