Android13重置锁屏（2）

        锁屏凭证包括图案、PIN、密码，系统开机默认无锁屏，重置锁屏的想法是在每次设置新锁屏凭证成功后，保存新锁屏凭证到文件，当再次设置时，用保存的锁屏凭证作为验证。

        回到LockSettingsService的setLockCredential方法，代码最后增加代码：

 @Overridepublic boolean setLockCredential(LockscreenCredential credential,LockscreenCredential savedCredential, int userId) {........................................final long identity = Binder.clearCallingIdentity();try {...............................notifySeparateProfileChallengeChanged(userId);onPostPasswordChanged(credential, userId);scheduleGc();//add codeSettings.Global.putString(mContext.getContentResolver(),"lockscreen_password", byteToHexString(credential.getCredential()));//add endreturn true;} finally {Binder.restoreCallingIdentity(identity);}}private String byteToHexString(byte [] byteHex){String strHex="";if(byteHex==null)return "";for(int i=0;i<byteHex.length;i++){strHex=strHex+String.format("%02X", byteHex[i]);}return strHex;}

将凭证的byte数组转成HEX码，保存到Settings，通过系统设置修改的锁屏凭证也会经过这里保存。

在定制化system service里面增加一个setPassword方法：

 @Overridepublic boolean setPassword(String pwd) throws RemoteException {long id = Binder.clearCallingIdentity();mContext.enforceCallingOrSelfPermission(Manifest.permission.ACCESS_KEYGUARD_SECURE_STORAGE,"YourService");mContext.enforceCallingOrSelfPermission(Manifest.permission.SET_AND_VERIFY_LOCKSCREEN_CREDENTIALS,"YourService");mContext.enforceCallingOrSelfPermission(Manifest.permission.SET_INITIAL_LOCK,YourService");LockPatternUtils lockPatternUtils = new LockPatternUtils(mContext); LockscreenCredential newCredential;String savePwd=Settings.Global.getString(mContext.getContentResolver(),"lockscreen_password");      int type=lockPatternUtils.getCredentialTypeForUser(UserHandle.USER_SYSTEM);    newCredential = LockscreenCredential.createPasswordOrNone(pwd);boolean iset=false;byte data[]= hexStringToByte(savePwd);switch (type){case LockPatternUtils.CREDENTIAL_TYPE_NONE:iset=lockPatternUtils.setLockCredential(newCredential,LockscreenCredential.createNone(), UserHandle.USER_SYSTEM);break;case LockPatternUtils.CREDENTIAL_TYPE_PATTERN:iset=lockPatternUtils.setLockCredential(newCredential,LockscreenCredential.createPattern(LockPatternUtils.byteArrayToPattern(data)), UserHandle.USER_SYSTEM);break;case LockPatternUtils.CREDENTIAL_TYPE_PIN:iset=lockPatternUtils.setLockCredential(newCredential,LockscreenCredential.createPinOrNone(new String(data)), UserHandle.USER_SYSTEM);break;case LockPatternUtils.CREDENTIAL_TYPE_PASSWORD:iset=lockPatternUtils.setLockCredential(newCredential,LockscreenCredential.createPasswordOrNone(new String(data)), UserHandle.USER_SYSTEM);break;default:break;}       Binder.restoreCallingIdentity(id);return iset;}private byte[] hexStringToByte(String str) {if(str==null) return null;if(str.length()%2!=0) str="0"+str;int len = (str.length()/2);byte[] result = new byte[len];char[] achar = str.toCharArray();for (int i = 0; i < len; i++) {int pos = i * 2;result[i] = (byte) (toByte(achar[pos]) << 4 | toByte(achar[pos + 1]));}return result;}private byte toByte(char c) {byte b = (byte) "0123456789ABCDEF".indexOf(c);if(b==-1)b = (byte) "0123456789abcdef".indexOf(c);return b;}

代码从保存的锁屏凭证获取值，并根据当前的锁屏方式，创建还原保存的锁屏作为验证，同时创建一个新的以pwd为密码的锁屏凭证，通过lockPatternUtils.setLockCredential设置。