android - 使用 Flutter 从方法中获取一些变量值

Question

我的代码:

import 'package:flutter/material.dart';
//My backend file
import '...';

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

class _UserProfileState extends State<UserProfile> {

Future _getUserInfo() async {
var user = await GetUserInfo.getInfo(
    widget.userName, widget.password, widget.token);

final String _firstName = user.firstName;
final String _email = user.email;
final String _cpf = user.cpf;


}

//As it didn't was clear enough I will show what I want to do

print(_cpf); // <- But this wont work

那么我需要什么(但我不知道该怎么做)？

1 - 获取这些“全名”、“电子邮件”和“cpf”字符串；

2 - 将它们设置为一些文本小部件。

我的问题是什么？

未使用局部变量“blockchainId”的值。尝试删除变量，或使用它。dart(unused_local_variable)

我不知道如何从方法中获取这些值并让外部代码使用它们的值...我知道我需要某种返回，否则它们将无法访问，但我不知道如何建立这个返回。

所有内部字符串都有有效值，如果我尝试打印它们(到方法中)，我会正确地看到我需要什么。

Answer 1

您可以在下面复制粘贴运行完整代码
第 1 步:假设您的 getUserInfo() 返回一个 User 对象
第 2 步:使用 bool loading 控制加载状态，模拟延迟 5 秒
第 3 步:在文本小部件

中使用 User 对象的信息

工作演示

代码 fragment

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

      User({this.firstName, this.email, this.cpf});
    }
...
class _UserProfileState extends State<UserProfile> {
  User user;
  bool loading = false;

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

完整代码

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<User> 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<UserProfile> {
  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: <Widget>[
          Text(
            '$count',
            style: TextStyle(color: Colors.white),
          ),
          Text(type,
              style:
                  TextStyle(color: Colors.white, fontWeight: FontWeight.normal))
        ],
      ));
}