我是新来的。
我正在使用拦截器来捕获 API 可能响应的 401 http 代码。但我真的不明白如何让它在它发生时进入登录页面。我想使用 Navigator，但它需要我没有的上下文。
class AuthInterceptor implements InterceptorContract {
@override
Future<RequestData> interceptRequest({RequestData data}) async {
print(data);
return data;
}
@override
Future<ResponseData> interceptResponse({ResponseData data}) async {
if (data.statusCode == 401) {
// What to do to go to login page?
}
return data;
}
}
有人可以帮我吗？
您可以复制粘贴下面运行完整代码
我使用官方天气示例来模拟这种情况，因为OPEN_WEATHER_API_KEY无效将返回401
您可以将上下文传递给AuthInterceptor初始化时
代码片段
@override
void initState() {
repository = WeatherRepository(
HttpClientWithInterceptor.build(interceptors: [
AuthInterceptor(context: context),
]),
);
...
class AuthInterceptor implements InterceptorContract {
final BuildContext context;
AuthInterceptor({this.context});
@override
Future<ResponseData> interceptResponse({ResponseData data}) async {
print("status code ${data.statusCode}");
if (data.statusCode == 401) {
Future.delayed(Duration(seconds: 1), () {
Navigator.pushNamedAndRemoveUntil(
context, "/", (Route<dynamic> route) => false);
});
}
return data;
}
}
工作演示
完整代码
import 'dart:convert';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:http_interceptor/http_interceptor.dart';
const String OPEN_WEATHER_API_KEY = "YOUR-KEY-HERE";
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
initialRoute: '/',
routes: {
'/': (context) => Login(),
'/home': (context) => HomeScreen(),
},
);
}
}
class HomeScreen extends StatefulWidget {
@override
_HomeScreenState createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
WeatherRepository repository;
@override
void initState() {
repository = WeatherRepository(
HttpClientWithInterceptor.build(interceptors: [
AuthInterceptor(context: context),
]),
);
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
centerTitle: true,
title: const Text('Weather App'),
actions: <Widget>[
IconButton(
icon: Icon(Icons.search),
onPressed: () {
showSearch(
context: context,
delegate: WeatherSearch(repository),
);
},
)
],
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(
Icons.wb_sunny,
size: 64,
color: Colors.grey,
),
Container(
height: 16,
),
Text(
"Search for a city",
style: TextStyle(
fontSize: 24.0,
fontWeight: FontWeight.w300,
),
textAlign: TextAlign.center,
),
],
),
),
);
}
}
class WeatherSearch extends SearchDelegate<String> {
int selected = -1;
WeatherRepository repo;
WeatherSearch(this.repo);
@override
List<Widget> buildActions(BuildContext context) {
return [
IconButton(
icon: Icon(Icons.clear),
onPressed: () {
selected = -1;
query = "";
},
)
];
}
@override
Widget buildLeading(BuildContext context) {
return IconButton(
icon: AnimatedIcon(
icon: AnimatedIcons.menu_arrow,
progress: transitionAnimation,
),
onPressed: () {
close(context, null);
},
);
}
@override
Widget buildResults(BuildContext context) {
final city = selected == -1 ? null : cities[selected];
return city != null ? buildWeatherCard(city) : buildEmptyCard();
}
@override
Widget buildSuggestions(BuildContext context) {
final suggestionList = query.isEmpty
? cities
: cities.where((p) => p["name"].toString().startsWith(query)).toList();
return ListView.builder(
itemCount: suggestionList.length,
itemBuilder: (context, index) {
return ListTile(
onTap: () {
selected = index;
query = cities[selected]["name"];
showResults(context);
},
title: Text(suggestionList[index]['name']),
subtitle: Text(suggestionList[index]['country']),
);
},
);
}
Widget buildWeatherCard(final city) {
return FutureBuilder(
future: repo.fetchCityWeather(city["id"]),
builder: (context, snapshot) {
if (snapshot.hasError) {
return Center(
child: Text(snapshot.error),
);
}
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(),
);
}
final weather = snapshot.data;
final iconWeather = weather["weather"][0]["icon"];
final main = weather["main"];
final wind = weather["wind"];
return Card(
margin: EdgeInsets.all(16.0),
child: Container(
width: Size.infinite.width,
padding: EdgeInsets.all(16.0),
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
ListTile(
leading: Tooltip(
child: Image.network(
"https://openweathermap.org/img/w/$iconWeather.png"),
message: weather["weather"][0]["main"],
),
title: Text(city["name"]),
subtitle: Text(city["country"]),
),
ListTile(
title: Text("${main["temp"]} °C"),
subtitle: Text("Temperature"),
),
ListTile(
title: Text("${main["temp_min"]} °C"),
subtitle: Text("Min Temperature"),
),
ListTile(
title: Text("${main["temp_max"]} °C"),
subtitle: Text("Max Temperature"),
),
ListTile(
title: Text("${main["humidity"]} %"),
subtitle: Text("Humidity"),
),
ListTile(
title: Text("${main["pressure"]} hpa"),
subtitle: Text("Pressure"),
),
ListTile(
title: Text("${wind["speed"]} m/s"),
subtitle: Text("Wind Speed"),
),
],
),
),
);
},
);
}
Widget buildEmptyCard() {
return Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(
Icons.wb_sunny,
size: 64,
color: Colors.grey,
),
Container(
height: 16,
),
Text(
"Search for a city",
style: TextStyle(
fontSize: 24.0,
fontWeight: FontWeight.w300,
),
textAlign: TextAlign.center,
),
],
),
);
}
}
const baseUrl = "https://api.openweathermap.org/data/2.5";
class WeatherRepository {
HttpClientWithInterceptor client;
WeatherRepository(this.client);
// Alternatively you can forget about using the Client and just doing the HTTP request with
// the HttpWithInterceptor.build() call.
// Future<Map<String, dynamic>> fetchCityWeather(int id) async {
// var parsedWeather;
// try {
// var response = await HttpWithInterceptor.build(
// interceptors: [WeatherApiInterceptor()])
// .get("$baseUrl/weather", params: {'id': "$id"});
// if (response.statusCode == 200) {
// parsedWeather = json.decode(response.body);
// } else {
// throw Exception("Error while fetching. \n ${response.body}");
// }
// } catch (e) {
// print(e);
// }
// return parsedWeather;
// }
Future<Map<String, dynamic>> fetchCityWeather(int id) async {
var parsedWeather;
try {
final response =
await client.get("$baseUrl/weather", params: {'id': "$id"});
if (response.statusCode == 200) {
parsedWeather = json.decode(response.body);
} else {
return Future.error(
"Error while fetching.",
StackTrace.fromString("${response.body}"),
);
}
} on SocketException {
return Future.error('No Internet connection ');
} on FormatException {
return Future.error('Bad response format ');
} on Exception {
return Future.error('Unexpected error ');
}
return parsedWeather;
}
}
class AuthInterceptor implements InterceptorContract {
final BuildContext context;
AuthInterceptor({this.context});
@override
Future<RequestData> interceptRequest({RequestData data}) async {
try {
data.params['appid'] = OPEN_WEATHER_API_KEY;
data.params['units'] = 'metric';
data.headers[HttpHeaders.contentTypeHeader] = "application/json";
} catch (e) {
print(e);
}
print(data.params);
return data;
}
@override
Future<ResponseData> interceptResponse({ResponseData data}) async {
print("status code ${data.statusCode}");
if (data.statusCode == 401) {
Future.delayed(Duration(seconds: 1), () {
Navigator.pushNamedAndRemoveUntil(
context, "/", (Route<dynamic> route) => false);
});
}
return data;
}
}
class Login extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Login Page')),
body: Center(
child: Column(
children: [
Text("Login Page"),
RaisedButton(
child: Text('Login Success'),
onPressed: () {
Navigator.pushReplacementNamed(context, '/home');
},
),
],
)));
}
}
const cities = [
{
"id": 707860,
"name": "Hurzuf",
"country": "UA",
"coord": {"lon": 34.283333, "lat": 44.549999}
},
{
"id": 519188,
"name": "Novinki",
"country": "RU",
"coord": {"lon": 37.666668, "lat": 55.683334}
},
{
"id": 1283378,
"name": "Gorkhā",
"country": "NP",
"coord": {"lon": 84.633331, "lat": 28}
},
];