Flutter项目开发笔记一：Form表单使用

import 'package:flutter/material.dart';
// 适应屏幕插件
import 'package:flutter_screenutil/flutter_screenutil.dart';
class LoginFormWidget extends StatefulWidget {  
        LoginFormWidget({Key key}) : super(key: key); 
 @override  
_LoginFormWidgetState createState() => _LoginFormWidgetState();
}
class _LoginFormWidgetState extends State<LoginFormWidget> {  
String _name;  
String _pwd;  
//全局key用来获取From表单组件  
GlobalKey<FormState> _formKey = GlobalKey<FormState>();  
@override  
Widget build(BuildContext context) {    
ScreenUtil.init(context,designSize: Size(750, 1334), allowFontScaling: false);    
return Scaffold(      
body: GestureDetector(        
behavior: HitTestBehavior.translucent,        
onTap: () {          
// 触摸收起键盘          
FocusScope.of(context).requestFocus(FocusNode());        
},        
child: ListView(          
children: [ _loginForm() ],       
 ),      
),    
);  
}  
// 登录表单  
Widget _loginForm() {    
return Container(      
child: Form(        
key: _formKey,        
child: Column(          
children: <Widget>[            
Container( margin:EdgeInsets.only(left: 22, right: 22, top: 10, bottom: 10),
 child: TextFormField( style: TextStyle(fontSize: 20), 
decoration: InputDecoration( 
hintText: '输入用户名', 
 prefixIcon: Icon(                      
Icons.person,                      
color: Colors.blue,                      
size: 26,                    
),                    
enabledBorder: UnderlineInputBorder( 
borderSide: BorderSide(color: Colors.blue),                   
),                  
),                  
onSaved: (value) {                   
 _name = value;                  
},                  
validator: (String value) {
return value.length >= 6 ? null : '账号最少6个字符';                  
},                
)),            
Container(              
margin: EdgeInsets.only(left: 22, right: 22),              
child: TextFormField(                
obscureText: true,                
style: TextStyle(color: Colors.blue, fontSize: 20),                
decoration: InputDecoration(                  
hintText: '输入密码',                  
prefixIcon: Icon(                    
Icons.lock_outline,                    
color: Colors.blue,                    
size: 26,                  
),                  
enabledBorder: UnderlineInputBorder(                    
borderSide: BorderSide(color: Colors.blue),                  
),                
),                
onSaved: (value) {

_pwd = value;                
},                
validator: (String value) {

return value.length < 6 ? '密码长度不够六位' : null;               
 },              
),            
),            
Container(              
margin: EdgeInsets.only(top: 30),             
 width: ScreenUtil().setWidth(660),              
height: ScreenUtil().setHeight(84),             
 child: RaisedButton(               
 // 设置圆角     
           shape: RoundedRectangleBorder(            
      borderRadius: BorderRadius.circular(20),          
      ),                
textColor: Colors.white,                
child: Text(               
   '登录',                  
style: TextStyle(fontSize: 18),                ),                
onPressed: () {                  
var loginForm = _formKey.currentState;                  
print(loginForm);                  
if (loginForm.validate()) {                    
loginForm.save();                    
print("username:" + _name + 'password:' + _pwd);                 
 }                },              ),            )          ],        ),      ),    ); 
 }}