Android指纹识别API讲解,一种更快更好的用户体验

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@TargetApi(23)
public class FingerprintDialogFragment extends DialogFragment {
  private FingerprintManager fingerprintManager;
  private CancellationSignal mCancellationSignal;
  private Cipher mCipher;
  private LoginActivity mActivity;
  private TextView errorMsg;
  /**
   * 标识是否是用户主动取消的认证。
   */
  private boolean isSelfCancelled;
  public void setCipher(Cipher cipher) {
    mCipher = cipher;
  }
  @Override
  public void onAttach(Context context) {
    super.onAttach(context);
    mActivity = (LoginActivity) getActivity();
  }
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    fingerprintManager = getContext().getSystemService(FingerprintManager.class);
    setStyle(DialogFragment.STYLE_NORMAL, android.R.style.Theme_Material_Light_Dialog);
  }
  @Nullable
  @Override
  public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fingerprint_dialog, container, false);
    errorMsg = v.findViewById(R.id.error_msg);
    TextView cancel = v.findViewById(R.id.cancel);
    cancel.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        dismiss();
        stopListening();
      }
    });
    return v;
  }
  @Override
  public void onResume() {
    super.onResume();
    // 开始指纹认证监听
    startListening(mCipher);
  }
  @Override
  public void onPause() {
    super.onPause();
    // 停止指纹认证监听
    stopListening();
  }
  private void startListening(Cipher cipher) {
    isSelfCancelled = false;
    mCancellatiOnSignal= new CancellationSignal();
    fingerprintManager.authenticate(new FingerprintManager.CryptoObject(cipher), mCancellationSignal, 0, new FingerprintManager.AuthenticationCallback() {
      @Override
      public void onAuthenticationError(int errorCode, CharSequence errString) {
        if (!isSelfCancelled) {
          errorMsg.setText(errString);
          if (errorCode == FingerprintManager.FINGERPRINT_ERROR_LOCKOUT) {
            Toast.makeText(mActivity, errString, Toast.LENGTH_SHORT).show();
            dismiss();
          }
        }
      }
      @Override
      public void onAuthenticationHelp(int helpCode, CharSequence helpString) {
        errorMsg.setText(helpString);
      }
      @Override
      public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {
        Toast.makeText(mActivity, "指纹认证成功", Toast.LENGTH_SHORT).show();
        mActivity.onAuthenticated();
      }
      @Override
      public void onAuthenticationFailed() {
        errorMsg.setText("指纹认证失败，请再试一次");
      }
    }, null);
  }
  private void stopListening() {
    if (mCancellationSignal != null) {
      mCancellationSignal.cancel();
      mCancellatiOnSignal= null;
      isSelfCancelled = true;
    }
  }
}

public class LoginActivity extends AppCompatActivity {
  private static final String DEFAULT_KEY_NAME = "default_key";
  KeyStore keyStore;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    if (supportFingerprint()) {
      initKey();
      initCipher();
    }
  }
  public boolean supportFingerprint() {
    if (Build.VERSION.SDK_INT <23) {
      Toast.makeText(this, "您的系统版本过低，不支持指纹功能", Toast.LENGTH_SHORT).show();
      return false;
    } else {
      KeyguardManager keyguardManager = getSystemService(KeyguardManager.class);
      FingerprintManager fingerprintManager = getSystemService(FingerprintManager.class);
      if (!fingerprintManager.isHardwareDetected()) {
        Toast.makeText(this, "您的手机不支持指纹功能", Toast.LENGTH_SHORT).show();
        return false;
      } else if (!keyguardManager.isKeyguardSecure()) {
        Toast.makeText(this, "您还未设置锁屏，请先设置锁屏并添加一个指纹", Toast.LENGTH_SHORT).show();
        return false;
      } else if (!fingerprintManager.hasEnrolledFingerprints()) {
        Toast.makeText(this, "您至少需要在系统设置中添加一个指纹", Toast.LENGTH_SHORT).show();
        return false;
      }
    }
    return true;
  }
  @TargetApi(23)
  private void initKey() {
    try {
      keyStore = KeyStore.getInstance("AndroidKeyStore");
      keyStore.load(null);
      KeyGenerator keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
      KeyGenParameterSpec.Builder builder = new KeyGenParameterSpec.Builder(DEFAULT_KEY_NAME,
          KeyProperties.PURPOSE_ENCRYPT |
              KeyProperties.PURPOSE_DECRYPT)
          .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
          .setUserAuthenticationRequired(true)
          .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7);
      keyGenerator.init(builder.build());
      keyGenerator.generateKey();
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  @TargetApi(23)
  private void initCipher() {
    try {
      SecretKey key = (SecretKey) keyStore.getKey(DEFAULT_KEY_NAME, null);
      Cipher cipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"
          + KeyProperties.BLOCK_MODE_CBC + "/"
          + KeyProperties.ENCRYPTION_PADDING_PKCS7);
      cipher.init(Cipher.ENCRYPT_MODE, key);
      showFingerPrintDialog(cipher);
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private void showFingerPrintDialog(Cipher cipher) {
    FingerprintDialogFragment fragment = new FingerprintDialogFragment();
    fragment.setCipher(cipher);
    fragment.show(getFragmentManager(), "fingerprint");
  }
  public void onAuthenticated() {
    Intent intent = new Intent(this, MainActivity.class);
    startActivity(intent);
    finish();
  }
}