Flutter：我没有得到网站的回复

Question

我在网站上编写了一个程序，我在其中使用虚拟 API - https://reqres.in/

现在，我正在制作一个 Http 服务文件，我在其中使用 getRequest 函数从 json 文件中获取响应，但我无法得到它。

这是文件-

import 'package:dio/dio.dart';

class HttpService {
  Dio? _dio;
  final baseURL="https://reqres.in/";

  HttpService() {
    _dio=Dio(BaseOptions(
      baseUrl: baseURL,
    ));

    initializeInterceptors();
  }

  Future<Response> getRequest(String endPoint) async {
    Response response;
    try {
      print("Getting response");
      response = await _dio!.get(endPoint);
      print("Got response");
    } on DioError catch (e) {
      print("Getting endpoint request failed");
      print(e.message);
      throw Exception(e.message);
    }
    print("Returning Response");
    return response;
  }

  initializeInterceptors() {
    _dio?.interceptors.add(InterceptorsWrapper(
      onError: (dioError, errorInterceptorHandler) {
        print(dioError.message);
      },
      onRequest: (requestOptions, requestInterceptorHandler) {
        print("${requestOptions.method} | ${requestOptions.path}");
        print("No error, request is successful");
      },
      onResponse: (response, responseInterceptorHandler) {
        print(response.data);
        print("We have got the response");
      }
    ));
  }
}

我在这个文件中使用这个函数，第 26 行：

import 'package:dio/dio.dart';
import 'package:dio_basics/http_service.dart';
import 'package:dio_basics/model/single_user_response.dart';
import 'package:dio_basics/model/user.dart';
import 'package:flutter/material.dart';

class SingleUserScreen extends StatefulWidget {
  @override
  _SingleUserScreenState createState() => _SingleUserScreenState();
}

class _SingleUserScreenState extends State<SingleUserScreen> {
  HttpService? http;
  SingleUserResponse? singleUserResponse;
  User? user;

  bool isLoading = false;

  Future getUser() async {
    Response response;
    try {
      isLoading = true;

      print("into get user");

      response = await http!.getRequest("/api/users?page=2");

      isLoading = false;
      print("Got Response");

      if (response.statusCode == 200) {
        print("Response is ok");
        setState(() {
          singleUserResponse = SingleUserResponse.fromJson(
              response.data); //To convert into map of <string dynamic>
          user = singleUserResponse!.user;
          if (user == null) {
            print("User is null");
          }
        });
      } else {
        print("Problem with status Code");
      }
    } on Exception catch (e) {
      isLoading = false;
      print(e.toString());
    }
  }

  @override
  void initState() {
    http=HttpService();
    super.initState();
    getUser();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Single User'),
      ),
      body: isLoading
          ? const Center(
              child: CircularProgressIndicator(),
            )
          : user != null ? Container(
            width: double.infinity,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Image.network(user!.avatar??""),
                  const SizedBox(
                    height: 16.0,
                  ),
                  Text(
                    "Hello ${user!.firstName} ${user!.lastName}"
                  )
                ],
              ),
          ) : const Center(child: Text('User is null'),),
    );
  }
}

这是输出日志-

into get user
Getting response
GET | /api/users?page=2
No error, request is successful

谁能告诉我，我的代码有什么错误，或者我做错了什么？

Answer 1

拦截器可能有问题检查此代码我已修复它

    import 'package:flutter/material.dart';
    import 'package:dio/dio.dart';
    import 'dart:convert';

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

    class MyApp extends StatelessWidget {
      // This widget is the root of your application.
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter Location',
          theme: ThemeData(
            primarySwatch: Colors.amber,
          ),
          home: SingleUserScreen(
            httpService: HttpService(),
          ),
        );
      }
    }

    class SingleUserScreen extends StatefulWidget {
      final HttpService httpService;
      const SingleUserScreen({
        Key? key,
        required this.httpService,
      }) : super(key: key);

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

    class _SingleUserScreenState extends State<SingleUserScreen> {
      Future<Users?> getUsers() async {
        try {
          print("into get user");
          final result = await widget.httpService.getRequest("/api/users?page=2");
          print("Got Response");
          if (result.statusCode == 200) {
            print("Response is ok");
            return usersFromMap(result. data);
          } else {
            print("Problem with status Code");
          }
        } on Exception catch (e) {
          print(e.toString());
        }
        return null;
      }

      @override
      void initState() {
        super.initState();
      }

      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: const Text('Single User'),
          ),
          body: FutureBuilder<Users?>(
            future: getUsers(),
            builder: (context, snapshot) {
              if (snapshot.hasData) {
                User? user = snapshot.data?.data.first;
                return SizedBox(
                  width: double.infinity,
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Image.network(user?.avatar ?? ""),
                      const SizedBox(
                        height: 16.0,
                      ),
                      Text("Hello ${user?.firstName} ${user?.lastName}")
                    ],
                  ),
                );
              }
              return const Center(
                child: CircularProgressIndicator(),
              );
            },
          ),
        );
      }
    }

    class HttpService {
      Dio? _dio;
      final baseURL = "https://reqres.in";

      HttpService() {
        _dio = Dio(BaseOptions(
          baseUrl: baseURL,
        ));
      }

      Future<Response> getRequest(String endPoint) async {
        return _dio!.get(endPoint);
      }

      initializeInterceptors() {
        _dio?.interceptors
            .add(InterceptorsWrapper(onError: (dioError, errorInterceptorHandler) {
          print(dioError.message);
        }, onRequest: (requestOptions, requestInterceptorHandler) {
          print(
              "${requestOptions.method} | ${requestOptions.baseUrl}${requestOptions.path}");
          print("No error, request is successful");
        }, onResponse: (response, responseInterceptorHandler) {
          print(response.data);
          print("We have got the response");
        }));
      }
    }

    Users usersFromMap(dynamic str) => Users.fromMap(str);

    String usersToMap(Users data) => json.encode(data.toMap());

    class Users {
      Users({
        required this.page,
        required this.perPage,
        required this.total,
        required this.totalPages,
        required this.data,
        required this.support,
      });

      int page;
      int perPage;
      int total;
      int totalPages;
      List<User> data;
      Support support;

      factory Users.fromMap(Map<String, dynamic> json) => Users(
            page: json["page"],
            perPage: json["per_page"],
            total: json["total"],
            totalPages: json["total_pages"],
            data: List<User>.from(json["data"].map((x) => User.fromMap(x))),
            support: Support.fromMap(json["support"]),
          );

      Map<String, dynamic> toMap() => {
            "page": page,
            "per_page": perPage,
            "total": total,
            "total_pages": totalPages,
            "data": List<dynamic>.from(data.map((x) => x.toMap())),
            "support": support.toMap(),
          };
    }

    class User {
      User({
        required this.id,
        required this.email,
        required this.firstName,
        required this.lastName,
        required this.avatar,
      });

      int id;
      String email;
      String firstName;
      String lastName;
      String avatar;

      factory User.fromMap(Map<String, dynamic> json) => User(
            id: json["id"],
            email: json["email"],
            firstName: json["first_name"],
            lastName: json["last_name"],
            avatar: json["avatar"],
          );

      Map<String, dynamic> toMap() => {
            "id": id,
            "email": email,
            "first_name": firstName,
            "last_name": lastName,
            "avatar": avatar,
          };
    }

    class Support {
      Support({
        required this.url,
        required this.text,
      });

      String url;
      String text;

      factory Support.fromMap(Map<String, dynamic> json) => Support(
            url: json["url"],
            text: json["text"],
          );

      Map<String, dynamic> toMap() => {
            "url": url,
            "text": text,
          };
    }