ex:
import 'package:flutter/material.dart';
void main() => runApp(LoginPage());
class LoginPage extends StatefulWidget {
@override
_LoginPageState createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
GlobalKey<FormState> _loginKey = GlobalKey<FormState>();
String _userName;
String _password;
void _login() {
var _loginForm = _loginKey.currentState;
if (_loginForm.validate()) {
_loginForm.save();
print('name: $_userName, password: $_password');
}
}
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(
padding: const EdgeInsets.all(10.0),
child: Form(
key: _loginKey,
child: Column(
children: <Widget>[
TextFormField(
decoration: InputDecoration(
labelText: '请输入用户名',
),
onSaved: (value) {
print('onSaved :$value');
_userName = value;
},
onFieldSubmitted: (value) {
print('onFieldSubmitted : $value');
},
),
TextFormField(
decoration: InputDecoration(
labelText: '请输入密码',
),
obscureText: true,
onSaved: (value) {
_password = value;
},
validator: (value) {
return value.length < 6 ? '密码长度不够6位' : null;
},
),
Container(
margin: const EdgeInsets.only(top: 20.0),
width: 400.0,
height: 40.0,
child: RaisedButton(
onPressed: () {
_login();
},
child: Text('登录'),
),
),
],
)),
)
],
),
),
),
);
}
}
输出: