前天偶尔运行代码，一个段异常映入眼帘，我擦android10上反射机制监听不到指纹id等数据了，原因是android10彻底抛弃了之前指纹的api。所以反射不到了。

怎么解决这个问题？我们换个思路当然反射依然可以，不过你需要在android9之前和之后的版本写不同的反射代码，首先之前的反射代码都是我抄的别人的，android10现在还没大神奉献，我也写不出来！！！！(这是关键)

所以我想到了，

根据当前指纹库创建一个密钥 判断秘钥状态来判断指纹库是否发生了改变。是不是很神奇，不是原创的，我也是看见别人给了这样一个思路。

我们设计一个吧！

1.设计一个初始化秘钥的方法(这个方法要可以重新生成和重复利用之前秘钥的功能，为什么？你问我为啥？因为要监听改变就要能获取上次的秘钥所以要可以重复利用秘钥，因为一旦指纹变化了，用户可能需要重置指纹重新设置指纹密码，那么就要重新生成新的秘钥。)

2，需要一个判断指纹是否改变的方法，使用cipher去验证刚才的key，如果指纹改变了会抛异常，捕获和这个异常就可以了。

不说废话了上代码：

package cn.lkk.lkk.util;

import android.content.Context;

import android.content.SharedPreferences;

import android.os.Build;

import android.security.keystore.KeyGenParameterSpec;

import android.security.keystore.KeyPermanentlyInvalidatedException;

import android.security.keystore.KeyProperties;

import android.support.annotation.RequiresApi;

import android.text.TextUtils;

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;

/**

* @author lkk

* @date 2019/08/23 10:01

*/

@RequiresApi(api = Build.VERSION_CODES.M)

public class CipherHelper

{

private static CipherHelper instance;

private static final String DEFAULT_KEY_NAME = "defaultKey";

private static final String KEYSTORE_ALIAS = "keyStoreAlias";

private static final String HAS_FINGER_KEY = "hasFingerKey";

private KeyGenerator mKeyGenerator;

private KeyStore keyStore;

private CipherHelper()

{

try

{

keyStore = KeyStore.getInstance("AndroidKeyStore");

}

catch (KeyStoreException e)

{

e.printStackTrace();

}

try

{

mKeyGenerator = KeyGenerator

.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");

}

catch (NoSuchAlgorithmException | NoSuchProviderException e)

{

throw new RuntimeException("Failed to get an instance of KeyGenerator", e);

}

}

publicstatic CipherHelper getInstance()

{

if (instance == null)

{

synchronized (CipherHelper.class)

{

if (instance == null)

{

instance = new CipherHelper();

}

}

}

return instance;

}

/**

* @des 创建cipher

* @author lkk

* @date 2019/08/23 10:05

*/

publicCipher createCipher()

{

try

{

return Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"

+ KeyProperties.BLOCK_MODE_CBC + "/"

+ KeyProperties.ENCRYPTION_PADDING_PKCS7);

}

catch (NoSuchAlgorithmException | NoSuchPaddingException e)

{

e.printStackTrace();

}

return null;

}

/**

* @des 初始化Cipher ,并判断指纹库是否发生了变化

* @author lkk

* @date 2019/08/23 10:17

*/

publicboolean initCipher(Cipher cipher)

{

try

{

keyStore.load(null);

SecretKey key = (SecretKey) keyStore.getKey(KEYSTORE_ALIAS, null);

if (cipher == null)

{

cipher = createCipher();

}

cipher.init(Cipher.ENCRYPT_MODE, key);

return false;

}

catch (KeyPermanentlyInvalidatedException e)

{

return true;

}

catch (KeyStoreException | CertificateException | UnrecoverableKeyException | IOException

| NoSuchAlgorithmException | InvalidKeyException e)

{

return false;

//throw new RuntimeException("Failed to init Cipher", e);

}

}

/**

* @param context

* @param createNewKey 是否创建新的密钥

* @des 根据当前指纹库创建一个密钥

* @author lkk

* @date 2019/08/23 10:30

*/

publicvoid createKey(Context context, boolean createNewKey)

{

if (context == null)

{

throw new RuntimeException("context can not be null");

}

SharedPreferences sharedPreferences = context.getSharedPreferences(DEFAULT_KEY_NAME, Context.MODE_PRIVATE);

try

{

//首先通过标志位判断用户之前是否创建了密钥,如果已经创建过了并且不需要重新创建就跳过

if (TextUtils.isEmpty(sharedPreferences.getString(HAS_FINGER_KEY, "")) || createNewKey)

{

//创建新密钥

KeyGenParameterSpec.Builder builder = new KeyGenParameterSpec.Builder(KEYSTORE_ALIAS,

KeyProperties.PURPOSE_ENCRYPT |

KeyProperties.PURPOSE_DECRYPT)

.setBlockModes(KeyProperties.BLOCK_MODE_CBC)

.setUserAuthenticationRequired(true)

.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N)

{

builder.setInvalidatedByBiometricEnrollment(true);

}

mKeyGenerator.init(builder.build());

mKeyGenerator.generateKey();

sharedPreferences.edit().putString(HAS_FINGER_KEY, "KEY").apply();

}

}

catch (InvalidAlgorithmParameterException e)

{

//throw new RuntimeException(e);

}

}

}

怎么使用呢？

开始监听

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

mCipher = CipherHelper.getInstance().createCipher();

CipherHelper.getInstance().createKey(getActivity(), false);

}

监听判断

if (CipherHelper.getInstance().initCipher(mCipher)){

//关闭指纹登录

//弹窗告知用户

}

重置监听Key

CipherHelper.getInstance().createKey(getActivity(), true);