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原文
参考
- https://pub.dev/packages/dio/versions/4.0.0
- https://pub.dev/packages/flutter_secure_storage
- https://pub.dev/packages/shared_preferences
正文
在本文中，我将解释如何使用 flutter dio (4.0.0)进行网络调用，以及如何在您的 flutter 应用程序中使用刷新令牌和访问令牌来处理授权时处理 401。
在阅读这篇文章之前，我希望你们对颤抖移动应用程序开发有一个基本的了解。
Basic Authentication flow with refresh and access tokens
正如您在上面的图中所看到的，很明显，在身份验证流中使用刷新和访问令牌时的流程是什么。登录后，您将获得两个称为刷新和访问的标记。此访问令牌快速过期(刷新令牌也过期，但是它将比访问令牌花费更多的时间)。当您使用过期的访问令牌发出请求时，响应中会出现状态码 401(未经授权)。在这种情况下，您必须从服务器请求一个新的令牌，并使用有效的访问令牌再次发出上一个请求。如果刷新令牌也已过期，您必须指示用户登录页面并强制再次登录。
Dio class
class DioUtil {
static Dio _instance;//method for getting dio instance Dio getInstance() {
if (_instance == null) {
_instance = createDioInstance();
}
return _instance;
}
Dio createDioInstance() {
var dio = Dio();// adding interceptor dio.interceptors.clear();
dio.interceptors.add(InterceptorsWrapper(onRequest: (options, handler) {
return handler.next(options);
}, onResponse: (response, handler) {
if (response != null) {
return handler.next(response);
} else {
return null;
}
}, onError: (DioError e, handler) async {
if (e.response != null) {
if (e.response.statusCode == 401) {//catch the 401 here
dio.interceptors.requestLock.lock();
dio.interceptors.responseLock.lock();
RequestOptions requestOptions = e.requestOptions;
await refreshToken();
Repository repository = Repository();
var accessToken = await repository.readData("accessToken");
final opts = new Options(method: requestOptions.method);
dio.options.headers["Authorization"] = "Bearer " + accessToken;
dio.options.headers["Accept"] = "*/*";
dio.interceptors.requestLock.unlock();
dio.interceptors.responseLock.unlock();
final response = await dio.request(requestOptions.path,
options: opts,
cancelToken: requestOptions.cancelToken,
onReceiveProgress: requestOptions.onReceiveProgress,
data: requestOptions.data,
queryParameters: requestOptions.queryParameters);
if (response != null) {
handler.resolve(response);
} else {
return null;
}
} else {
handler.next(e);
}
}
}));
return dio;
}
static refreshToken() async {
Response response;
Repository repository = Repository();
var dio = Dio();
final Uri apiUrl = Uri.parse(BASE_PATH + "auth/reIssueAccessToken");
var refreshToken = await repository.readData("refreshToken");
dio.options.headers["Authorization"] = "Bearer " + refreshToken;
try {
response = await dio.postUri(apiUrl);
if (response.statusCode == 200) {
LoginResponse loginResponse =
LoginResponse.fromJson(jsonDecode(response.toString()));
repository.addValue('accessToken', loginResponse.data.accessToken);
repository.addValue('refreshToken', loginResponse.data.refreshToken);
} else {
print(response.toString()); //TODO: logout
}
} catch (e) {
print(e.toString()); //TODO: logout
}
}
}
以上是完整的课程，我将解释其中最重要的部分。
主要是，正如您在 createDioInstance 方法中看到的，您必须添加一个拦截器来捕获 401。当 401 发生在 error: (DioError e，handler) async {}被调用时。所以你的内心
- Check the error code(401), 检查错误代码(401) ,
- Get new access token 获取新的访问令牌
await refreshToken();
上面的代码将调用 refreshToken 方法并在存储库中存储新的刷新和访问令牌。(对于存储库，您可以使用 secure storage or shared preferences)
- 复制前一个请求并设置新的访问令牌
RequestOptions requestOptions = e.requestOptions;
Repository repository = Repository();
var accessToken = await repository.readData("accessToken");
final opts = new Options(method: requestOptions.method);
dio.options.headers["Authorization"] = "Bearer " + accessToken;
dio.options.headers["Accept"] = "*/*";
- Make the previous call again
final response = await dio.request(requestOptions.path,
options: opts,
cancelToken: requestOptions.cancelToken,
onReceiveProgress: requestOptions.onReceiveProgress,
data: requestOptions.data,
queryParameters: requestOptions.queryParameters);
一旦收到回复，就 call
handler.resolve(response);
然后响应将被发送到您调用 api 的位置，如下所示。
var dio = DioUtil().getInstance();
final String apiUrl = (BASE_PATH + "payments/addNewPayment/");
var accessToken = await repository.readData("accessToken");
dio.options.headers["Authorization"] = "Bearer " + accessToken;
dio.options.headers["Accept"] = "*/*";//response will be assigned to response variable
response = await dio.post(apiUrl, data: event.paymentRequest.toJson());
Thats all. happy coding :)
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