android指纹解锁

In this tutorial, we’ll be discussing the Android Fingerprint API and implement a Fingerprint Dialog in our android application.

在本教程中，我们将讨论Android Fingerprint API，并在android应用程序中实现Fingerprint Dialog。

Android指纹管理器 (Android Fingerprint Manager)

Fingerprint Manager is the class used to access the Fingerprint hardware from the device (if it exists).

指纹管理器是用于从设备（如果存在）访问指纹硬件的类。

Google recommends authenticating fingerprint in applications by displaying a DialogFragment with a Fingerprint icon to the user.

Google建议通过向用户显示带有指纹图标的DialogFragment来对应用程序中的指纹进行身份验证。

In order to implement Fingerprint Authentication, you need to add the following permission in the AndroidManifest.xml file:

为了实现指纹认证，您需要在AndroidManifest.xml文件中添加以下权限 ：

<uses-permission android:name="android.permission.USE_FINGERPRINT" />

Following are the steps to implement Fingerprint Authentication in your application:

以下是在您的应用程序中实现指纹认证的步骤：

• Check whether there is a secure lock on the lock screen检查锁屏上是否有安全锁
• Check whether the Fingerprint Hardware is available using the FingerprintManager class.使用FingerprintManager类检查指纹硬件是否可用。
• Check whether the user has enrolled at least one fingerprint.检查用户是否注册了至少一个指纹。
• Get access to Android keystore to store a key used to initiate a Cipher.获取对Android密钥库的访问权限，以存储用于启动密码的密钥。
• Start the Authentication Method and add the callback methods启动身份验证方法并添加回调方法

The Android Keystore system lets you store cryptographic keys in a container to make it more difficult to extract from the device.

Android Keystore系统可让您将加密密钥存储在容器中，以使其更难从设备中提取。

项目结构 (Project Structure)

码 (Code)

The code for the activity_main.xml layout is given below:

下面给出了activity_main.xml布局的代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="https://schemas.android.com/apk/res/android"xmlns:app="https://schemas.android.com/apk/res-auto"xmlns:tools="https://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".MainActivity"><Buttonandroid:id="@+id/button"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="START AUTHENTICATION"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toTopOf="parent" /></android.support.constraint.ConstraintLayout>

The code for the dialog_fingerprint.xml is given below:

下面给出了dialog_fingerprint.xml的代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="https://schemas.android.com/apk/res/android"xmlns:app="https://schemas.android.com/apk/res-auto"xmlns:tools="https://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="wrap_content"android:paddingLeft="24dp"android:paddingTop="24dp"android:paddingRight="24dp"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"><TextViewandroid:id="@+id/titleTextView"android:layout_width="0dp"android:layout_height="wrap_content"android:text="Fingerprint Dialog"android:textAppearance="?android:attr/textAppearanceLarge"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent" /><TextViewandroid:id="@+id/subtitleTextView"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginTop="20dp"android:text="Confirm fingerprint to continue."app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toBottomOf="@id/titleTextView" /><android.support.design.widget.FloatingActionButtonandroid:id="@+id/fab"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginTop="28dp"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintTop_toBottomOf="@id/subtitleTextView"app:srcCompat="@drawable/ic_fingerprint_white_24dp" /><TextViewandroid:id="@+id/errorTextView"android:layout_width="0dp"android:layout_height="0dp"android:layout_marginStart="16dp"android:gravity="center_vertical"android:text="Touch sensor"app:layout_constraintBottom_toBottomOf="@id/fab"app:layout_constraintLeft_toRightOf="@id/fab"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toTopOf="@id/fab" /><LinearLayoutandroid:id="@+id/buttons"style="?android:attr/buttonBarStyle"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginTop="16dp"android:gravity="end"android:orientation="horizontal"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toBottomOf="@id/fab"><Buttonandroid:id="@+id/btnCancel"style="?android:attr/buttonBarButtonStyle"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="Cancel" /></LinearLayout></android.support.constraint.ConstraintLayout>

The FingerprintHelper.java class is where we define the methods for authentication and initialization of Fingerprint and related class objects:

在FingerprintHelper.java类中，我们定义了指纹和相关类对象的身份验证和初始化方法：

package com.journaldev.androidfingerprintapi;import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.fingerprint.FingerprintManager;
import android.os.CancellationSignal;
import android.support.v4.app.ActivityCompat;public class FingerprintHelper extends FingerprintManager.AuthenticationCallback {private Context mContext;private FingerprintManager mFingerprintManager;private CancellationSignal mCancellationSignal;private Callback mCallback;public FingerprintHelper(FingerprintManager fingerprintManager, Context context, Callback callback) {mContext = context;mFingerprintManager = fingerprintManager;mCallback = callback;}public boolean isFingerprintAuthAvailable() {return mFingerprintManager.isHardwareDetected()&& mFingerprintManager.hasEnrolledFingerprints();}public void startAuthentication(FingerprintManager manager, FingerprintManager.CryptoObject cryptoObject) {if (!isFingerprintAuthAvailable())return;mCancellationSignal = new CancellationSignal();if (ActivityCompat.checkSelfPermission(mContext, Manifest.permission.USE_FINGERPRINT) != PackageManager.PERMISSION_GRANTED) {return;}manager.authenticate(cryptoObject, mCancellationSignal, 0, this, null);}public void stopListening() {if (mCancellationSignal != null) {mCancellationSignal.cancel();mCancellationSignal = null;}}@Overridepublic void onAuthenticationError(int errMsgId, CharSequence errString) {mCallback.onError(errString.toString());}@Overridepublic void onAuthenticationHelp(int helpMsgId, CharSequence helpString) {mCallback.onHelp(helpString.toString());}@Overridepublic void onAuthenticationFailed() {mCallback.onAuthenticated(false);}@Overridepublic void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {mCallback.onAuthenticated(true);}public interface Callback {void onAuthenticated(boolean b);void onError(String s);void onHelp(String s);}
}

manager.authenticate(cryptoObject, mCancellationSignal, 0, this, null); starts the authentication.

manager.authenticate(cryptoObject, mCancellationSignal, 0, this, null); 开始认证。

The Callback interface is used to pass the information to the UI which eventually gets displayed to the user.

回调接口用于将信息传递到UI，最终将其显示给用户。

The code for the MainActivity.java class is given below:

MainActivity.java类的代码如下：

package com.journaldev.androidfingerprintapi;import android.support.v4.hardware.fingerprint.FingerprintManagerCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;public class MainActivity extends AppCompatActivity implements View.OnClickListener {Button button;FingerprintManagerCompat managerCompat;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);button = findViewById(R.id.button);button.setOnClickListener(this);}private void showFingerPrintDialog() {FingerprintDialog fragment = new FingerprintDialog();fragment.setContext(this);fragment.show(getSupportFragmentManager(), "");}@Overridepublic void onClick(View v) {switch (v.getId()) {case R.id.button:managerCompat = FingerprintManagerCompat.from(MainActivity.this);if (managerCompat.isHardwareDetected() && managerCompat.hasEnrolledFingerprints()) {showFingerPrintDialog();} else {Toast.makeText(getApplicationContext(), "Fingerprint not supported", Toast.LENGTH_SHORT).show();}break;}}}

managerCompat = FingerprintManagerCompat.from(MainActivity.this); initialises the FingerprintCompat class object.

managerCompat = FingerprintManagerCompat.from(MainActivity.this); 初始化FingerprintCompat类对象。

isHardwareDetected() and hasEnrolledFingerprints() are used to check whether the fingerprint authentication is possible before showing the Dialog.

isHardwareDetected()和hasEnrolledFingerprints()用于在显示对话框之前检查指纹身份验证是否可行。

The code for the FingerprintDialog.java is given below:

FingerprintDialog.java的代码如下：

package com.journaldev.androidfingerprintapi;import android.app.KeyguardManager;
import android.content.Context;
import android.content.Intent;
import android.hardware.fingerprint.FingerprintManager;
import android.os.Bundle;
import android.security.keystore.KeyGenParameterSpec;
import android.security.keystore.KeyPermanentlyInvalidatedException;
import android.security.keystore.KeyProperties;
import android.support.v4.app.DialogFragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;public class FingerprintDialog extends DialogFragmentimplements FingerprintHelper.Callback {Button mCancelButton;public static final String DEFAULT_KEY_NAME = "default_key";FingerprintManager mFingerprintManager;private FingerprintManager.CryptoObject mCryptoObject;private FingerprintHelper mFingerprintHelper;KeyStore mKeyStore = null;KeyGenerator mKeyGenerator = null;KeyguardManager mKeyguardManager;private Context mContext;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setRetainInstance(true);setStyle(DialogFragment.STYLE_NORMAL, android.R.style.Theme_Material_Light_Dialog);try {mKeyStore = KeyStore.getInstance("AndroidKeyStore");} catch (KeyStoreException e) {e.printStackTrace();}try {mKeyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (NoSuchProviderException e) {e.printStackTrace();}Cipher defaultCipher;try {defaultCipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"+ KeyProperties.BLOCK_MODE_CBC + "/"+ KeyProperties.ENCRYPTION_PADDING_PKCS7);} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {throw new RuntimeException("Failed to get an instance of Cipher", e);}mKeyguardManager = getContext().getSystemService(KeyguardManager.class);mFingerprintManager = getContext().getSystemService(FingerprintManager.class);mFingerprintHelper = new FingerprintHelper(mFingerprintManager, getContext(), this);if (!mKeyguardManager.isKeyguardSecure()) {Toast.makeText(getContext(),"Lock screen not set up.\n"+ "Go to 'Settings -> Security -> Fingerprint' to set up a fingerprint",Toast.LENGTH_LONG).show();return;}createKey(DEFAULT_KEY_NAME);if (initCipher(defaultCipher, DEFAULT_KEY_NAME)) {mCryptoObject = new FingerprintManager.CryptoObject(defaultCipher);}}private boolean initCipher(Cipher cipher, String keyName) {try {mKeyStore.load(null);SecretKey key = (SecretKey) mKeyStore.getKey(keyName, null);cipher.init(Cipher.ENCRYPT_MODE, key);return true;} catch (KeyPermanentlyInvalidatedException e) {Toast.makeText(mContext, "Keys are invalidated after created. Retry the purchase\n"+ e.getMessage(),Toast.LENGTH_LONG).show();return false;} catch (KeyStoreException | CertificateException | UnrecoverableKeyException | IOException| NoSuchAlgorithmException | InvalidKeyException e) {Toast.makeText(mContext, "Failed to init cipher", Toast.LENGTH_LONG).show();return false;}}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View v = inflater.inflate(R.layout.dialog_fingerprint, container, false);mCancelButton = v.findViewById(R.id.btnCancel);mCancelButton.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {dismiss();}});return v;}@Overridepublic void onResume() {super.onResume();if (mCryptoObject != null) {mFingerprintHelper.startAuthentication(mFingerprintManager, mCryptoObject);}}@Overridepublic void onPause() {super.onPause();mFingerprintHelper.stopListening();}public void setContext(Context context) {mContext = context;}public void createKey(String keyName) {try {mKeyStore.load(null);KeyGenParameterSpec.Builder builder = new KeyGenParameterSpec.Builder(keyName,KeyProperties.PURPOSE_ENCRYPT |KeyProperties.PURPOSE_DECRYPT).setBlockModes(KeyProperties.BLOCK_MODE_CBC).setUserAuthenticationRequired(true).setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7);mKeyGenerator.init(builder.build());mKeyGenerator.generateKey();} catch (NoSuchAlgorithmException | InvalidAlgorithmParameterException| CertificateException | IOException e) {throw new RuntimeException(e);}}@Overridepublic void onAuthenticated(boolean b) {if (b) {Toast.makeText(mContext.getApplicationContext(), "Auth success", Toast.LENGTH_LONG).show();dismiss();} elseToast.makeText(mContext.getApplicationContext(), "Auth failed", Toast.LENGTH_LONG).show();}@Overridepublic void onError(String s) {Toast.makeText(mContext.getApplicationContext(), s, Toast.LENGTH_LONG).show();}@Overridepublic void onHelp(String s) {Toast.makeText(mContext.getApplicationContext(), "Auth help message:" + s, Toast.LENGTH_LONG).show();}
}

setRetainInstance(true); is used to prevent multiple instances of the DialogFragment from getting created when the config changes.

setRetainInstance(true); 用于防止在配置更改时创建DialogFragment的多个实例。

The output of the above application in action is given below:

上面应用程序的输出如下：

So on my phone when I authenticated with the correct fingerprint, it showed the appropriate Toast message.

因此，当我使用正确的指纹进行身份验证时，手机上会显示相应的Toast消息。

That brings an end to this tutorial. You can download the project from the link below:

这样就结束了本教程。 您可以从下面的链接下载项目：

翻译自: https://www.journaldev.com/23881/android-fingerprint-lock

android指纹解锁