在应用程序中检测指纹传感器抽头?

是的,这是真的。迈克尔·多德所说的。我们可以得到各种各样的事件,比如指纹成功、失败或快速移除之类的事件。轻触事件更有可能是指纹快速去除。我没有找到任何获取tap事件的直接api。而是使用身份验证来获取自定义活动中的tap。实现下面的代码并找到处理tap事件的各种适当事件。

@TargetApi(Build.VERSION_CODES.M)
public class FingerprintUiHelper extends FingerprintManager.AuthenticationCallback {

/**
 * The timeout for the error to be displayed. Returns to the normal UI after this.
 */
private static final long ERROR_TIMEOUT_MILLIS = 1600;
/**
 * The timeout for the success to be displayed. Calls {@link Callback#onAuthenticated()} after this.
 */
private static final long SUCCESS_DELAY_MILLIS = 1300;
/**
 * Alias for our key in the Android Key Store
 **/
private static final String KEY_NAME = "my_key";

/**
 * The {@link Cipher} used to init {@link FingerprintManager}
 */
private Cipher mCipher;
/**
 * The {@link KeyStore} used to initiliaze the key {@link #KEY_NAME}
 */
private KeyStore mKeyStore;
/**
 * The {@link KeyGenerator} used to generate the key {@link #KEY_NAME}
 */
private KeyGenerator mKeyGenerator;
/**
 * The {@link android.hardware.fingerprint.FingerprintManager.CryptoObject}
 */
private final FingerprintManager mFingerprintManager;
/**
 * The {@link ImageView} that is used to show the authent state
 */
private final ImageView mIcon;
/**
 * The {@link TextView} that is used to show the authent state
 */
private final TextView mErrorTextView;

private final Callback mCallback;
/**
 * The {@link CancellationSignal} used after an error happens
 */
private CancellationSignal mCancellationSignal;
/**
 * Used if the user cancelled the authentication by himself
 */
private boolean mSelfCancelled;

/**
 * Builder class for {@link FingerprintUiHelper} in which injected fields from Dagger
 * holds its fields and takes other arguments in the {@link #build} method.
 */
public static class FingerprintUiHelperBuilder {
    private final FingerprintManager mFingerPrintManager;

    public FingerprintUiHelperBuilder(FingerprintManager fingerprintManager) {
        mFingerPrintManager = fingerprintManager;
    }

    public FingerprintUiHelper build(ImageView icon, TextView errorTextView, Callback callback) {
        return new FingerprintUiHelper(mFingerPrintManager, icon, errorTextView,
                callback);
    }
}

/**
 * Constructor for {@link FingerprintUiHelper}. This method is expected to be called from
 * only the {@link FingerprintUiHelperBuilder} class.
 */
private FingerprintUiHelper(FingerprintManager fingerprintManager,
                            ImageView icon, TextView errorTextView, Callback callback) {
    mFingerprintManager = fingerprintManager;
    mIcon = icon;
    mErrorTextView = errorTextView;
    mCallback = callback;
}

/**
 * Starts listening to {@link FingerprintManager}
 *
 * @throws SecurityException If the hardware is not available, or the permission are not set
 */
public void startListening() throws SecurityException {
    if (initCipher()) {
        FingerprintManager.CryptoObject cryptoObject = new FingerprintManager.CryptoObject(mCipher);
        if (!isFingerprintAuthAvailable()) {
            return;
        }
        mCancellationSignal = new CancellationSignal();
        mSelfCancelled = false;
        mFingerprintManager.authenticate(cryptoObject, mCancellationSignal, 0 /* flags */, this, null);
        mIcon.setImageResource(R.drawable.ic_fp_40px);
    }
}

/**
 * Stops listening to {@link FingerprintManager}
 */
public void stopListening() {
    if (mCancellationSignal != null) {
        mSelfCancelled = true;
        mCancellationSignal.cancel();
        mCancellationSignal = null;
    }
}

/**
 * Called by {@link FingerprintManager} if the authentication threw an error.
 */
@Override
public void onAuthenticationError(int errMsgId, CharSequence errString) {
    if (!mSelfCancelled) {
        showError(errString);
        mIcon.postDelayed(new Runnable() {
            @Override
            public void run() {
                mCallback.onError();
            }
        }, ERROR_TIMEOUT_MILLIS);
    }
}

/**
 * Called by {@link FingerprintManager} if the user asked for help.
 */
@Override
public void onAuthenticationHelp(int helpMsgId, CharSequence helpString) {
    showError(helpString);
}

/**
 * Called by {@link FingerprintManager} if the authentication failed (bad finger etc...).
 */
@Override
public void onAuthenticationFailed() {
    showError(mIcon.getResources().getString(
            R.string.pin_code_fingerprint_not_recognized));
}

/**
 * Called by {@link FingerprintManager} if the authentication succeeded.
 */
@Override
public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {
    mErrorTextView.removeCallbacks(mResetErrorTextRunnable);
    mIcon.setImageResource(R.drawable.ic_fingerprint_success);
    mErrorTextView.setTextColor(
            mErrorTextView.getResources().getColor(R.color.success_color, null));
    mErrorTextView.setText(
            mErrorTextView.getResources().getString(R.string.pin_code_fingerprint_success));
    mIcon.postDelayed(new Runnable() {
        @Override
        public void run() {
            mCallback.onAuthenticated();
        }
    }, SUCCESS_DELAY_MILLIS);
}

/**
 * Tells if the {@link FingerprintManager#isHardwareDetected()}, {@link FingerprintManager#hasEnrolledFingerprints()},
 * and {@link KeyguardManager#isDeviceSecure()}
 * 
 * @return true if yes, false otherwise
 * @throws SecurityException If the hardware is not available, or the permission are not set
 */
public boolean isFingerprintAuthAvailable() throws SecurityException {
    return mFingerprintManager.isHardwareDetected()
            && mFingerprintManager.hasEnrolledFingerprints()
            && ((KeyguardManager) mIcon.getContext().getSystemService(Context.KEYGUARD_SERVICE)).isDeviceSecure();
}

/**
 * Initialize the {@link Cipher} instance with the created key in the {@link #createKey()}
 * method.
 *
 * @return {@code true} if initialization is successful, {@code false} if the lock screen has
 * been disabled or reset after the key was generated, or if a fingerprint got enrolled after
 * the key was generated.
 */
private boolean initCipher() {
    try {
        if (mKeyStore == null) {
            mKeyStore = KeyStore.getInstance("AndroidKeyStore");
        }
        createKey();
        mKeyStore.load(null);
        SecretKey key = (SecretKey) mKeyStore.getKey(KEY_NAME, null);
        mCipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
        mCipher.init(Cipher.ENCRYPT_MODE, key);
        return true;
    } catch (NoSuchPaddingException | KeyStoreException | CertificateException | UnrecoverableKeyException | IOException
            | NoSuchAlgorithmException | InvalidKeyException e) {
        return false;
    }
}

/**
 * Creates a symmetric key in the Android Key Store which can only be used after the user has
 * authenticated with fingerprint.
 */
public void createKey() {
    // The enrolling flow for fingerprint. This is where you ask the user to set up fingerprint
    // for your flow. Use of keys is necessary if you need to know if the set of
    // enrolled fingerprints has changed.
    try {
        // Set the alias of the entry in Android KeyStore where the key will appear
        // and the constrains (purposes) in the constructor of the Builder
        mKeyGenerator = KeyGenerator.getInstance(
                KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
        mKeyGenerator.init(new KeyGenParameterSpec.Builder(KEY_NAME,
                KeyProperties.PURPOSE_ENCRYPT |
                        KeyProperties.PURPOSE_DECRYPT)
                .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
                        // Require the user to authenticate with a fingerprint to authorize every use
                        // of the key
                .setUserAuthenticationRequired(true)
                .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
                .build());
        mKeyGenerator.generateKey();
    } catch (NoSuchProviderException | NoSuchAlgorithmException | InvalidAlgorithmParameterException e) {
        throw new RuntimeException(e);
    }
}

/**
 * Show an error on the UI using {@link #mIcon} and {@link #mErrorTextView}
 */
private void showError(CharSequence error) {
    mIcon.setImageResource(R.drawable.ic_fingerprint_error);
    mErrorTextView.setText(error);
    mErrorTextView.setTextColor(
            mErrorTextView.getResources().getColor(R.color.warning_color, null));
    mErrorTextView.removeCallbacks(mResetErrorTextRunnable);
    mErrorTextView.postDelayed(mResetErrorTextRunnable, ERROR_TIMEOUT_MILLIS);
}

/**
 * Run by {@link #showError(CharSequence)} with delay to reset the original UI after an error.
 */
Runnable mResetErrorTextRunnable = new Runnable() {
    @Override
    public void run() {
        mErrorTextView.setTextColor(
                mErrorTextView.getResources().getColor(R.color.hint_color, null));
        mErrorTextView.setText(
                mErrorTextView.getResources().getString(R.string.pin_code_fingerprint_text));
        mIcon.setImageResource(R.drawable.ic_fp_40px);
    }
};

/**
 * The interface used to call the original Activity/Fragment... that uses this helper.
 */
public interface Callback {
    void onAuthenticated();

    void onError();
}