Android google登录问题12501-authenti

mGoogleApiClient.isConnected()
旧的代码中，这句代码报出异常状态错误。导致接下来的new GoogleApiClient.Builder(activity)报错GoogleApiClient.getContext()' on a null object reference

首先找了一个api，发现实现方式已经过时。
mSignInClient=GoogleSignIn.getClient(activity, mGoogleSignInOptions);
取代了GoogleApiClient

public class MyNewActivity extends AppCompatActivity {

    private static final int RC_SIGN_IN = 9001;

    private GoogleSignInClient mSignInClient;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        GoogleSignInOptions options =
               new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                        .requestScopes(Drive.SCOPE_FILE)
                        .build();

        mSignInClient = GoogleSignIn.getClient(this, options);
    }

    private void signIn() {
        // Launches the sign in flow, the result is returned in onActivityResult
        Intent intent = mSignInClient.getSignInIntent();
        startActivityForResult(intent, RC_SIGN_IN);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == RC_SIGN_IN) {
            Task<GoogleSignInAccount> task = 
                    GoogleSignIn.getSignedInAccountFromIntent(data);
            if (task.isSuccessful()) {
                // Sign in succeeded, proceed with account
                GoogleSignInAccount acct = task.getResult();
            } else {
                // Sign in failed, handle failure and update UI
                // ...
            }
        }
    }
}

然后就报错12501错误，其实这个码在api里是用户取消的意思
但是人家没爆出来给我们用。
没办法，只能用activityResult方法返回的resultCode字段来判断是否为取消行为了。投机取消的解决这个问题。