用颤振方法求取一些变量值

您可以复制粘贴，运行下面的完整代码 步骤1：假设您的getUserInfo()返回aUser对象 步骤2：使用bool loading若要控制加载状态，请在延迟5秒内进行模拟。 步骤3：使用User对象在文本小部件中的信息

工作演示

enter image description here

代码段

class User { String firstName; String email; String cpf;

  User({this.firstName, this.email, this.cpf});
}

... class _UserProfileState extends State { User user; bool loading = false;

Future _getUserInfo() async { setState(() { loading = true; }); ... @override void initState() {
_getUserInfo(); super.initState(); } ... return loading ? Center( child: CircularProgressIndicator(), ) : Stack( children: [ 全码

import 'package:flutter/material.dart'; import 'dart:ui' as ui;

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

class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Profile Demo', theme: ThemeData( primarySwatch: Colors.blue, ), home: UserProfile(title: 'Profile'), ); } }

class User { String firstName; String email; String cpf;

User({this.firstName, this.email, this.cpf}); }

class GetUserInfo { static Future getInfo( String userName, String password, String token) async { await Future.delayed(Duration(seconds: 5)); return User(firstName: "abc", email: "def", cpf: "123"); } }

class UserProfile extends StatefulWidget { UserProfile({Key key, this.title, this.userName, this.password, this.token}) : super(key: key); final String title; final String userName; final String password; final String token;

@override _UserProfileState createState() => _UserProfileState(); }

class _UserProfileState extends State { User user; bool loading = false;

Future _getUserInfo() async { setState(() { loading = true; });

user = await GetUserInfo.getInfo(
    widget.userName, widget.password, widget.token);

setState(() {
  loading = false;
});

}

@override void initState() { // TODO: implement initState _getUserInfo(); super.initState(); }

@override Widget build(BuildContext context) { final _width = MediaQuery.of(context).size.width; final _height = MediaQuery.of(context).size.height; final String imgUrl = 'https://pixel.nymag.com/imgs/daily/selectall/2017/12/26/26-eric-schmidt.w700.h700.jpg';

return loading
    ? Center(
        child: CircularProgressIndicator(),
      )
    : Stack(
        children: <Widget>[
          Container(
            color: Colors.blue,
          ),
          Image.network(
            imgUrl,
            fit: BoxFit.fill,
          ),
          BackdropFilter(
              filter: ui.ImageFilter.blur(
                sigmaX: 6.0,
                sigmaY: 6.0,
              ),
              child: Container(
                decoration: BoxDecoration(
                  color: Colors.blue.withOpacity(0.9),
                  borderRadius: BorderRadius.all(Radius.circular(50.0)),
                ),
              )),
          Scaffold(
              appBar: AppBar(
                title: Text(widget.title),
                centerTitle: false,
                elevation: 0.0,
                backgroundColor: Colors.transparent,
              ),
              drawer: Drawer(
                child: Container(),
              ),
              backgroundColor: Colors.transparent,
              body: Center(
                child: Column(
                  children: <Widget>[
                    SizedBox(
                      height: _height / 12,
                    ),
                    CircleAvatar(
                      radius: _width < _height ? _width / 4 : _height / 4,
                      backgroundImage: NetworkImage(imgUrl),
                    ),
                    SizedBox(
                      height: _height / 25.0,
                    ),
                    Text(
                      user.firstName,
                      style: TextStyle(
                          fontWeight: FontWeight.bold,
                          fontSize: _width / 15,
                          color: Colors.white),
                    ),
                    Padding(
                      padding: EdgeInsets.only(
                          top: _height / 30,
                          left: _width / 8,
                          right: _width / 8),
                      child: Text(
                        user.cpf,
                        style: TextStyle(
                            fontWeight: FontWeight.normal,
                            fontSize: _width / 25,
                            color: Colors.white),
                        textAlign: TextAlign.center,
                      ),
                    ),
                    Divider(
                      height: _height / 30,
                      color: Colors.white,
                    ),
                    Row(
                      children: <Widget>[
                        rowCell(343, 'POSTS'),
                        rowCell(673826, 'FOLLOWERS'),
                        rowCell(275, 'FOLLOWING'),
                      ],
                    ),
                    Divider(height: _height / 30, color: Colors.white),
                    Padding(
                      padding: EdgeInsets.only(
                          left: _width / 8, right: _width / 8),
                      child: FlatButton(
                        onPressed: () {},
                        child: Container(
                            child: Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Icon(Icons.person),
                            SizedBox(
                              width: _width / 30,
                            ),
                            Text('FOLLOW')
                          ],
                        )),
                        color: Colors.blue[50],
                      ),
                    ),
                  ],
                ),
              ))
        ],
      );

}

Widget rowCell(int count, String type) => Expanded( child: Column( children: [ Text( '$count', style: TextStyle(color: Colors.white), ), Text(type, style: TextStyle(color: Colors.white, fontWeight: FontWeight.normal)) ], ));