后台Android中的指纹扫描仪

Question

我只是想问。 我见过许多应用程序，它们可以让您输入密码，或者您只需触摸扫描仪即可，而无需专门打开指纹对话框。 有谁知道这是如何实现的？

这是来自react-native-biometrics的片段，该片段在react native中提供了此功能：

    Signature signature = Signature.getInstance("SHA256withRSA");
    KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
            keyStore.load(null);

    PrivateKey privateKey = (PrivateKey) keyStore.getKey(biometricKeyAlias, null);
    signature.initSign(privateKey);

    FingerprintManager.CryptoObject cryptoObject = new FingerprintManager.CryptoObject(signature);

    ReactNativeBiometricsDialog dialog = new ReactNativeBiometricsDialog();
    dialog.init(title, cryptoObject, getSignatureCallback(payload, promise));

    Activity activity = getCurrentActivity();
    dialog.show(activity.getFragmentManager(), "fingerprint_dialog");