关于flutter:Flutter-如何处理401-未授权的-Dio-拦截器

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原文

https://medium.com/@wmnkrisha…

参考

• https://pub.dev/packages/dio/…
• https://pub.dev/packages/flut…
• https://pub.dev/packages/shar…

注释

在本文中，我将解释如何应用 flutter dio (4.0.0) 进行网络调用，以及如何在您的 flutter 应用程序中应用刷新令牌和拜访令牌来解决受权时解决 401。

在浏览这篇文章之前，我心愿你们对颤动挪动利用程序开发有一个根本的理解。

Basic Authentication flow with refresh and access tokens

正如您在下面的图中所看到的，很显著，在身份验证流中应用刷新和拜访令牌时的流程是什么。登录后，您将取得两个称为刷新和拜访的标记。此拜访令牌疾速过期 (刷新令牌也过期，然而它将比拜访令牌破费更多的工夫)。当您应用过期的拜访令牌发出请求时，响应中会呈现状态码 401(未经受权)。在这种状况下，您必须从服务器申请一个新的令牌，并应用无效的拜访令牌再次收回上一个申请。如果刷新令牌也已过期，您必须批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
    }
  }
}

以上是残缺的课程，我将解释其中最重要的局部。

次要是，正如您在 createDioInstance 办法中看到的，您必须增加一个拦截器来捕捉 401。当 401 产生在 error: (DioError e，handler) async {} 被调用时。所以你的心田

1. Check the error code(401), 查看错误代码 (401) ,
2. Get new access token 获取新的拜访令牌

await refreshToken();

下面的代码将调用 refreshToken 办法并在存储库中存储新的刷新和拜访令牌。(对于存储库，您能够应用 secure storage or shared preferences)

3. 复制前一个申请并设置新的拜访令牌

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"] = "*/*";

4. 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);

而后响应将被发送到您调用 api 的地位，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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