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关联帐号登录 (Android)

“关联的帐号登录”功能可为已将 Google 帐号与您的服务相关联的用户启用一键登录 Google。这改善了用户的体验，因为他们只需点击一下即可登录，而无需重新输入用户名和密码。这还可以降低用户在您的服务上创建重复帐号的可能性。

“关联的帐号登录”功能是适用于 Android 的一键登录流程的一部分。这意味着，如果您的应用已经启用一键快捷功能，则无需导入单独的库。

在本文档中，您将了解如何修改 Android 应用以支持关联的帐号登录。

运作方式

您可以在一键登录流程中选择显示关联的账号。
如果用户在 Google 上登录，并且已将其 Google 账号与其在您服务中的账号相关联，则系统将为关联的账号返回 ID 令牌。
系统会向用户显示一键登录提示，并提供使用其关联的帐号登录您的服务的选项。
如果用户选择继续使用关联的帐号，系统会将用户的 ID 令牌返回给您的应用。您需要将该令牌与在第 2 步中发送到服务器的令牌进行匹配，以识别已登录的用户。

初始设置

设置您的开发环境

在开发主机上获取最新的 Google Play 服务：

打开 Android SDK 管理器。

在 SDK Tools 下，找到 Google Play services。
如果这些软件包的状态均为“未安装”，请同时选中它们，然后点击 Install Packages（安装软件包）。

配置您的应用

在项目级 build.gradle 文件中，同时在 buildscript 和 allprojects 部分添加 Google 的 Maven 制品库。

buildscript {
    repositories {
        google()
    }
}

allprojects {
    repositories {
        google()
    }
}

将“Link with Google”API 的依赖项添加到您的模块的应用级 Gradle 文件（通常为 app/build.gradle）：
```
dependencies {
  implementation 'com.google.android.gms:play-services-auth:21.1.1'
}
```

修改您的 Android 应用以支持关联的账号登录功能

在关联的账号登录流程结束时，系统会向您的应用返回一个 ID 令牌。应先验证该 ID 令牌的完整性，然后再让用户登录。

以下代码示例详细介绍了检索、验证 ID 令牌以及随后让用户登录的步骤。

创建一个 activity 以接收登录 intent 的结果

Kotlin

  private val activityResultLauncher = registerForActivityResult(
    ActivityResultContracts.StartIntentSenderForResult()) { result ->
    if (result.resultCode == RESULT_OK) {
      try {
        val signInCredentials = Identity.signInClient(this)
                                .signInCredentialFromIntent(result.data)
        // Review the Verify the integrity of the ID token section for
        // details on how to verify the ID token
        verifyIdToken(signInCredential.googleIdToken)
      } catch (e: ApiException) {
        Log.e(TAG, "Sign-in failed with error code:", e)
      }
    } else {
      Log.e(TAG, "Sign-in failed")
    }
  }

Java

  private final ActivityResultLauncher<IntentSenderResult>
    activityResultLauncher = registerForActivityResult(
    new ActivityResultContracts.StartIntentSenderForResult(),
    result -> {
    If (result.getResultCode() == RESULT_OK) {
        try {
          SignInCredential signInCredential = Identity.getSignInClient(this)
                         .getSignInCredentialFromIntent(result.getData());
          verifyIdToken(signInCredential.getGoogleIdToken());
        } catch (e: ApiException ) {
          Log.e(TAG, "Sign-in failed with error:", e)
        }
    } else {
        Log.e(TAG, "Sign-in failed")
    }
});

构建登录请求

Kotlin

private val tokenRequestOptions =
GoogleIdTokenRequestOptions.Builder()
  .supported(true)
  // Your server's client ID, not your Android client ID.
  .serverClientId(getString("your-server-client-id")
  .filterByAuthorizedAccounts(true)
  .associateLinkedAccounts("service-id-of-and-defined-by-developer",
                           scopes)
  .build()

Java

 private final GoogleIdTokenRequestOptions tokenRequestOptions =
     GoogleIdTokenRequestOptions.Builder()
  .setSupported(true)
  .setServerClientId("your-service-client-id")
  .setFilterByAuthorizedAccounts(true)
  .associateLinkedAccounts("service-id-of-and-defined-by-developer",
                            scopes)
  .build()

启动“登录待处理”intent

Kotlin

 Identity.signInClient(this)
    .beginSignIn(
  BeginSignInRequest.Builder()
    .googleIdTokenRequestOptions(tokenRequestOptions)
  .build())
    .addOnSuccessListener{result ->
      activityResultLauncher.launch(result.pendingIntent.intentSender)
  }
  .addOnFailureListener {e ->
    Log.e(TAG, "Sign-in failed because:", e)
  }

Java

 Identity.getSignInClient(this)
  .beginSignIn(
    BeginSignInRequest.Builder()
      .setGoogleIdTokenRequestOptions(tokenRequestOptions)
      .build())
  .addOnSuccessListener(result -> {
    activityResultLauncher.launch(
        result.getPendingIntent().getIntentSender());
})
.addOnFailureListener(e -> {
  Log.e(TAG, "Sign-in failed because:", e);
});

验证 ID 令牌的完整性

如需验证令牌是否有效，请确保满足以下条件：

ID 令牌由 Google 正确签名。使用 Google 的公钥（以 JWK 或 PEM 格式提供）来验证令牌的签名。这些密钥会定期轮替；请检查响应中的 Cache-Control 标头，以确定何时应再次检索它们。
ID 令牌中 aud 的值等于应用的某个客户端 ID。通过进行这项检查，可以防止向恶意应用颁发的 ID 令牌用于访问应用后端服务器上同一用户的数据。
ID 令牌中 iss 的值等于 accounts.google.com 或 https://accounts.google.com。
ID 令牌的过期时间 (exp) 尚未过去。
如果您需要验证该 ID 令牌代表的是 Google Workspace 或 Cloud 组织帐号，则可以检查 hd 声明，该声明指示用户的托管网域。仅允许特定网域的成员访问资源时，必须使用此方法。缺少此声明表示帐号不属于 Google 托管的网域。

我们强烈建议您使用适合您的平台的 Google API 客户端库或通用 JWT 库，而不是自行编写代码来执行这些验证步骤。对于开发和调试，您可以调用我们的 tokeninfo 验证端点。

使用 Google API 客户端库

建议使用 Java Google API 客户端库在生产环境中验证 Google ID 令牌。

Java

  import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
  import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken.Payload;
  import com.google.api.client.googleapis.auth.oauth2.GoogleIdTokenVerifier;

  ...

  GoogleIdTokenVerifier verifier = new GoogleIdTokenVerifier.Builder(transport, jsonFactory)
      // Specify the CLIENT_ID of the app that accesses the backend:
      .setAudience(Collections.singletonList(CLIENT_ID))
      // Or, if multiple clients access the backend:
      //.setAudience(Arrays.asList(CLIENT_ID_1, CLIENT_ID_2, CLIENT_ID_3))
      .build();

  // (Receive idTokenString by HTTPS POST)

  GoogleIdToken idToken = verifier.verify(idTokenString);
  if (idToken != null) {
    Payload payload = idToken.getPayload();

    // Print user identifier
    String userId = payload.getSubject();
    System.out.println("User ID: " + userId);

    // Get profile information from payload
    String email = payload.getEmail();
    boolean emailVerified = Boolean.valueOf(payload.getEmailVerified());
    String name = (String) payload.get("name");
    String pictureUrl = (String) payload.get("picture");
    String locale = (String) payload.get("locale");
    String familyName = (String) payload.get("family_name");
    String givenName = (String) payload.get("given_name");

    // Use or store profile information
    // ...

  } else {
    System.out.println("Invalid ID token.");
  }

GoogleIdTokenVerifier.verify() 方法可验证 JWT 签名、aud 声明、iss 声明和它们exp 声明。

如果您需要验证该 ID 令牌代表的是 Google Workspace 或 Cloud 组织帐号，则可以通过检查 Payload.getHostedDomain() 方法返回的域名来验证 hd 声明。

Calling the tokeninfo endpoint

An easy way to validate an ID token signature for debugging is to use the tokeninfo endpoint. Calling this endpoint involves an additional network request that does most of the validation for you while you test proper validation and payload extraction in your own code. It is not suitable for use in production code as requests may be throttled or otherwise subject to intermittent errors.

To validate an ID token using the tokeninfo endpoint, make an HTTPS POST or GET request to the endpoint, and pass your ID token in the id_token parameter. For example, to validate the token "XYZ123", make the following GET request:

https://oauth2.googleapis.com/tokeninfo?id_token=XYZ123

If the token is properly signed and the iss and exp claims have the expected values, you will get a HTTP 200 response, where the body contains the JSON-formatted ID token claims. Here's an example response:

{
 // These six fields are included in all Google ID Tokens.
 "iss": "https://accounts.google.com",
 "sub": "110169484474386276334",
 "azp": "1008719970978-hb24n2dstb40o45d4feuo2ukqmcc6381.apps.googleusercontent.com",
 "aud": "1008719970978-hb24n2dstb40o45d4feuo2ukqmcc6381.apps.googleusercontent.com",
 "iat": "1433978353",
 "exp": "1433981953",

 // These seven fields are only included when the user has granted the "profile" and
 // "email" OAuth scopes to the application.
 "email": "testuser@gmail.com",
 "email_verified": "true",
 "name" : "Test User",
 "picture": "https://lh4.googleusercontent.com/-kYgzyAWpZzJ/ABCDEFGHI/AAAJKLMNOP/tIXL9Ir44LE/s99-c/photo.jpg",
 "given_name": "Test",
 "family_name": "User",
 "locale": "en"
}

Warning: Once you get these claims, you still need to check that the aud claim contains one of your app's client IDs. If it does, then the token is both valid and intended for your client, and you can safely retrieve and use the user's unique Google ID from the sub claim.

If you need to validate that the ID token represents a Google Workspace account, you can check the hd claim, which indicates the hosted domain of the user. This must be used when restricting access to a resource to only members of certain domains. The absence of this claim indicates that the account does not belong to a Google Workspace hosted domain.