Android设备指纹认证

介绍一个最简单的方式进行认证指纹，老规矩文章最后附上DEMO

现在很多设备都还没有真正的将指纹使用起来，用得最多就是屏幕解锁，和微信支付宝的支付时使用，其他应用发现很少使用，其实指纹认证目前已经很成熟。

这里用代码来介绍：登录界面（指纹认证）->指纹认证成功主界面

1、登录界面

/**
 * https://blog.csdn.net/generallizhong
 */

public class LoginActivity extends Activity {

    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();
        }
    }
//检测设备
    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();
    }

首先在onCreate()方法中，调用了supportFingerprint()方法来判断当前设备是否支持指纹认证功能。这一点是非常重要的，因为当设备不支持指纹认证的时候，还需要及时切换到如图案、密码等其他的认证方式。

当设备支持指纹认证的时候，再分为两步，第一步生成一个对称加密的Key，第二步生成一个Cipher对象，这都是Android指纹认证API要求的标准用法。得到了Cipher对象之后，我们创建FingerprintDialogFragment的实例，并将Cipher对象传入，再将FingerprintDialogFragment显示出来就可以了。

2、指纹认证的相关逻辑在这里完成

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();
    }

    //监听认证成功与失败
    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();//认证成功后就可以写成功后的代码逻辑
            }

            @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;
        }
    }

最后的最后，当指纹认证成功之后，会在FingerprintDialogFragment的回调当中调用LoginActivity的onAuthenticated()方法，然后界面会跳转到MainActivity

在使用中可能会出现很多开发或厂商自行使用指纹认证图片，这样就造成五花八门的指纹认证如，建议统一使用官方提供图标图标下载，

文中的指纹认证Demo实现过程很简单，但是切记它是不能单独使用的，必须要配合着图案或其他认证方式一起来使用，因为一定要提供一个在设备不支持指纹情况下的其他认证方式

DEMO下载：

CSDN:下载

百度网盘：下载提取码： 447q

Android设备指纹认证

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