什么是令牌？
Fleet Engine 要求使用 JSON Web 令牌 (JWT)， 适当的服务账号，用于低信任度 API 方法调用 环境。低信任的环境包括智能手机和浏览器。JWT 来自您的服务器，这是一个完全可信的环境。JWT 经过签名和加密，并传递给客户端，以供后续服务器使用 直至过期或失效。
您的后端应使用 标准的应用默认凭据机制。制造商 请务必使用由相应服务账号签名的 JWT。对于 服务账号角色的列表，请参阅 Fleet Engine 服务账号角色 Fleet Engine 基础知识。
如需详细了解 JSON 网络令牌，请参阅 JSON 网络令牌 Fleet Engine 基础知识。
客户端如何获取令牌？
驾驶员或消费者使用相应的 身份验证凭据，那么通过该设备发布的任何更新都必须使用 相应的授权令牌，用于向 Fleet Engine 传达 应用权限。
作为开发者，您的客户端实现应该能够 执行以下操作：
- 从您的服务器提取 JSON 网络令牌。
- 在令牌过期之前重复使用，以最大限度地减少令牌刷新。
- 在令牌过期时刷新。
GMTDAuthorization 协议在位置信息更新时提取 JSON Web 令牌
根据 GMTD AuthorizationContext 对象指定。SDK
必须将令牌与更新信息打包在一起，以发送到 Fleet Engine。
请确保您的服务器端实现可以提前
初始化 SDK。
如需详细了解 Fleet Engine 预期的令牌，请参阅 为 Fleet Engine 颁发 JSON Web 令牌。
providerID 与 Google Cloud 的项目 ID 相同 项目。如需了解如何设置 Google Cloud 项目，请参阅 创建 Fleet Engine 项目。
身份验证令牌提取程序示例
以下示例展示了 GMTDAuthorization 的实现
协议。
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