Google登录-onActivityResult-resultCode始终等于0（RESULT_CANCELED）

Question

我正在集成Android的Google登录，并且我希望返回id_token以便可以通过服务器进行身份验证。我遵循了https://developers.google.com/identity/sign-in/android/backend-auth

中的所有步骤

问题在于onActivityResult（）的结果代码为0

GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestEmail()
            .requestIdToken(getString(R.string.server_client_id))
            .build();

private void signIn() {
    Intent signInIntent = mGoogleSignInClient.getSignInIntent();
    startActivityForResult(signInIntent, RC_SIGN_IN);
}

onActivityResult：

    super.onActivityResult(requestCode, resultCode, data);
    Log.d(TAG, "data : " + resultCode + " | " + data  + " || " + RC_SIGN_IN + " ||| " + requestCode);

你知道为什么resultCode总是等于0（RESULT_CANCELED）吗？