从 Smart Lock（密码专用）迁移到凭据管理器

// Retrieves the user's saved password for your app from their
// password provider.
val getPasswordOption = GetPasswordOption()

val getCredRequest = GetCredentialRequest(
    listOf(getPasswordOption)
)

fun launchSignInFlow() {
    coroutineScope.launch {
        try {
            // Attempt to retrieve the credential from the Credential Manager.
            val result = credentialManager.getCredential(
                // Use an activity-based context to avoid undefined system UI
                // launching behavior.
                context = activityContext,
                request = getCredRequest
            )

            // Process the successfully retrieved credential.
            handleSignIn(result)
        } catch (e: GetCredentialException) {
            // Handle any errors that occur during the credential retrieval
            // process.
            handleFailure(e)
        }
    }
}

private fun handleSignIn(result: GetCredentialResponse) {
    // Extract the credential from the response.
    val credential = result.credential

    // Determine the type of credential and handle it accordingly.
    when (credential) {
        is PasswordCredential -> {
            val username = credential.id
            val password = credential.password

            // Use the extracted username and password to perform
            // authentication.
        }

        else -> {
            // Handle unrecognized credential types.
            Log.e(TAG, "Unexpected type of credential")
        }
    }
}

private fun handleFailure(e: GetCredentialException) {
    // Handle specific credential retrieval errors.
    when (e) {
        is GetCredentialCancellationException -> {
            /* This exception is thrown when the user intentionally cancels
                the credential retrieval operation. Update the application's state
                accordingly. */
        }

        is GetCredentialCustomException -> {
            /* This exception is thrown when a custom error occurs during the
                credential retrieval flow. Refer to the documentation of the
                third-party SDK used to create the GetCredentialRequest for
                handling this exception. */
        }

        is GetCredentialInterruptedException -> {
            /* This exception is thrown when an interruption occurs during the
                credential retrieval flow. Determine whether to retry the
                operation or proceed with an alternative authentication method. */
        }

        is GetCredentialProviderConfigurationException -> {
            /* This exception is thrown when there is a mismatch in
                configurations for the credential provider. Verify that the
                provider dependency is included in the manifest and that the
                required system services are enabled. */
        }

        is GetCredentialUnknownException -> {
            /* This exception is thrown when the credential retrieval
                operation fails without providing any additional details. Handle
                the error appropriately based on the application's context. */
        }

        is GetCredentialUnsupportedException -> {
            /* This exception is thrown when the device does not support the
                Credential Manager feature. Inform the user that credential-based
                authentication is unavailable and guide them to an alternative
                authentication method. */
        }

        is NoCredentialException -> {
            /* This exception is thrown when there are no viable credentials
                available for the user. Prompt the user to sign up for an account
                or provide an alternative authentication method. Upon successful
                authentication, store the login information using
                androidx.credentials.CredentialManager.createCredential to
                facilitate easier sign-in the next time. */
        }

        else -> {
            // Handle unexpected exceptions.
            Log.w(TAG, "Unexpected exception type: ${e::class.java.name}")
        }
    }
}