获取授权令牌

什么是令牌？

对于来自低信任环境（智能手机和浏览器）的 API 方法调用，Fleet Engine 要求使用 JSON Web 令牌 (JWT)。

JWT 源自您的服务器，经过签名和加密后传递给客户端，以供后续服务器交互使用，直到过期或不再有效为止。

关键细节

如需详细了解 JSON Web 令牌，请参阅 Fleet Engine 基础知识中的 JSON Web 令牌。

客户如何获取令牌？

司机或消费者使用相应的身份验证凭据登录您的应用后，从该设备发出的任何更新都必须使用相应的授权令牌，以便向 Fleet Engine 传达应用的权限。

作为开发者，您的客户端实现应能够执行以下操作：

  • 从服务器获取 JSON Web 令牌。
  • 重复使用令牌，直到其过期，以尽可能减少令牌刷新次数。
  • 在令牌过期时刷新令牌。

GMTDAuthorization 协议会在位置更新时根据 GMTD AuthorizationContext 对象提取 JSON Web 令牌。SDK 必须将令牌与更新信息打包在一起，然后发送到 Fleet Engine。 请确保您的服务器端实现可以在初始化 SDK 之前签发令牌。

如需详细了解 Fleet Engine 期望的令牌，请参阅为 Fleet Engine 签发 JSON Web 令牌。

providerID 与您的 Google Cloud 项目的项目 ID 相同。如需了解如何设置 Google Cloud 项目，请参阅创建 Fleet Engine 项目。

身份验证令牌提取器示例

以下示例展示了 GMTDAuthorization 协议的实现。

Swift

import GoogleRidesharingDriver

private let providerURL = "INSERT_YOUR_TOKEN_PROVIDER_URL"

class SampleAccessTokenProvider: NSObject, GMTDAuthorization {
  private struct AuthToken {
    // The cached vehicle token.
    let token: String
    // Keep track of when the token expires for caching.
    let expiration: TimeInterval
    // Keep track of the vehicle ID the cached token is for.
    let vehicleID: String
  }

  enum AccessTokenError: Error {
    case missingAuthorizationContext
    case missingData
  }

  private var authToken: AuthToken?

  func fetchToken(
    with authorizationContext: GMTDAuthorizationContext?,
    completion: @escaping GMTDAuthTokenFetchCompletionHandler
  ) {
    // Get the vehicle ID from the authorizationContext. This is set by the Driver SDK.
    guard let authorizationContext = authorizationContext else {
      completion(nil, AccessTokenError.missingAuthorizationContext)
      return
    }
    let vehicleID = authorizationContext.vehicleID

    // If appropriate, use the cached token.
    if let authToken = authToken,
      authToken.expiration > Date.now.timeIntervalSince1970 && authToken.vehicleID == vehicleID
    {
      completion(authToken.token, nil)
      return
    }

    // Otherwise, try to fetch a new token from your server.
    let request = URLRequest(url: URL(string: providerURL))
    let task = URLSession.shared.dataTask(with: request) { [weak self] data, _, error in
      guard let strongSelf = self else { return }
      guard error == nil else {
        completion(nil, error)
        return
      }

      // Replace the following key values with the appropriate keys based on your
      // server's expected response.
      let vehicleTokenKey = "VEHICLE_TOKEN_KEY"
      let tokenExpirationKey = "TOKEN_EXPIRATION"
      guard let data = data,
        let fetchData = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
        let token = fetchData[vehicleTokenKey] as? String,
        let expiration = fetchData[tokenExpirationKey] as? Double
      else {
        completion(nil, AccessTokenError.missingData)
        return
      }

      strongSelf.authToken = AuthToken(
        token: token, expiration: expiration, vehicleID: vehicleID)
      completion(token, nil)
    }
    task.resume()
  }
}

Objective-C

#import "SampleAccessTokenProvider.h"
#import <GoogleRidesharingDriver/GoogleRidesharingDriver.h>

// SampleAccessTokenProvider.h
@interface SampleAccessTokenProvider : NSObject<GMTDAuthorization>
@end

static NSString *const PROVIDER_URL = @"INSERT_YOUR_TOKEN_PROVIDER_URL";

// SampleAccessTokenProvider.m
@implementation SampleAccessTokenProvider{
  // The cached vehicle token.
  NSString *_cachedVehicleToken;
  // Keep track of the vehicle ID the cached token is for.
  NSString *_lastKnownVehicleID;
  // Keep track of when tokens expire for caching.
  NSTimeInterval _tokenExpiration;
}

-   (void)fetchTokenWithContext:(nullable GMTDAuthorizationContext *)authorizationContext
                   completion:(nonnull GMTDAuthTokenFetchCompletionHandler)completion {

  if (!completion) {
   NSAssert(NO, @"%s encountered an unexpected nil completion.", __PRETTY_FUNCTION__);
   return;
  }

  // Get the vehicle ID from the authorizationContext. This is set by the Driver SDK.
  NSString *vehicleID = authorizationContext.vehicleID;
  if (!vehicleID) {
    NSAssert(NO, @"Vehicle ID is missing from authorizationContext.");
    return;
  }

  // Clear cached vehicle token if vehicle ID has changed.
  if (![_lastKnownVehicleID isEqual:vehicleID]) {
    _tokenExpiration = 0.0;
    _cachedVehicleToken = nil;
  }
  _lastKnownVehicleID = vehicleID;

  // Clear cached vehicletoken if it has expired.
  if ([[NSDate date] timeIntervalSince1970] > _tokenExpiration) {
    _cachedVehicleToken = nil;
  }

  // If appropriate, use the cached token.
  if (_cachedVehicleToken) {
    completion(_cachedVehicleToken, nil);
    return;
  }
  // Otherwise, try to fetch a new token from your server.
  NSURL *requestURL = [NSURL URLWithString:PROVIDER_URL];
  NSMutableURLRequest *request =
      [[NSMutableURLRequest alloc] initWithURL:requestURL];
  request.HTTPMethod = @"GET";
  // Replace the following key values with the appropriate keys based on your
  // server's expected response.
  NSString *vehicleTokenKey = @"VEHICLE_TOKEN_KEY";
  NSString *tokenExpirationKey = @"TOKEN_EXPIRATION";
  __weak typeof(self) weakSelf = self;
  void (^handler)(NSData *_Nullable data, NSURLResponse *_Nullable response,
                  NSError *_Nullable error) =
      ^(NSData *_Nullable data, NSURLResponse *_Nullable response, NSError *_Nullable error) {
        typeof(self) strongSelf = weakSelf;
        if (error) {
          completion(nil, error);
          return;
        }

        NSError *JSONError;
        NSMutableDictionary *JSONResponse =
            [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&JSONError];

        if (JSONError) {
          completion(nil, JSONError);
          return;
        } else {
          // Sample code only. No validation logic.
          id expirationData = JSONResponse[tokenExpirationKey];
          if ([expirationData isKindOfClass:[NSNumber class]]) {
            NSTimeInterval expirationTime = ((NSNumber *)expirationData).doubleValue;
            strongSelf->_tokenExpiration = [[NSDate date] timeIntervalSince1970] + expirationTime;
          }
          strongSelf->_cachedVehicleToken = JSONResponse[vehicleTokenKey];
          completion(JSONResponse[vehicleTokenKey], nil);
        }
      };
  NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
  NSURLSession *mainQueueURLSession =
      [NSURLSession sessionWithConfiguration:config delegate:nil
                               delegateQueue:[NSOperationQueue mainQueue]];
  NSURLSessionDataTask *task = [mainQueueURLSession dataTaskWithRequest:request completionHandler:handler];
  [task resume];
}

@end

后续步骤

初始化 Driver SDK