淺談Android指紋解鎖技術(shù)

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

FingerprintManagerCompat fingerprint = FingerprintManagerCompat.from(this);  //v4包下的API，包裝內(nèi)部已經(jīng)判斷Android系統(tǒng)版本是否大于6.0，這也是官方推薦的方式
FingerprintManager fingerprint2 = (FingerprintManager) getSystemService(Context.FINGERPRINT_SERVICE); //Android 6.0包下的API

/**
   * Determine if fingerprint hardware is present and functional.
   * @return true if hardware is present and functional, false otherwise.
   */
  fingerprint.isHardwareDetected(); // 判斷設(shè)備是否支持指紋解鎖

/**
   * Determine if there is at least one fingerprint enrolled.
   * @return true if at least one fingerprint is enrolled, false otherwise
   */
  fingerprint.hasEnrolledFingerprints(); //判斷設(shè)備是否以保存過(guò)指紋信息，至少需要保存過(guò)一個(gè)

/**
   * @param crypto object associated with the call or null if none required.  //不太理解，加密指紋特征還是什么，可以不加密置為null
   * @param flags optional flags; should be 0 //設(shè)置標(biāo)記，暫時(shí)無(wú)用
   * @param cancel an object that can be used to cancel authentication   //取消驗(yàn)證
   * @param callback an object to receive authentication events  //系統(tǒng)認(rèn)證完成之后，回調(diào)該接口
   * @param handler an optional handler for events //處理callback接口后，界面的處理，默認(rèn)是主線程handler
   */
  fingerprint.authenticate(crypto, flags,cancel,callback,handler) //驗(yàn)證指紋

再來(lái)說(shuō)明各個(gè)參數(shù)的實(shí)現(xiàn)

  crypto = null; //可以置為null，愿意了解的人可以參考底部博客和源碼
  flags = 0;
  cancel = new CancellationSignal();
  callback = new FingerprintManagerCompat.AuthenticationCallback() {
      @Override
      public void onAuthenticationError(int errMsgId, CharSequence errString) {
        super.onAuthenticationError(errMsgId, errString);
        //驗(yàn)證錯(cuò)誤時(shí)，回調(diào)該方法。當(dāng)連續(xù)驗(yàn)證5次錯(cuò)誤時(shí)，將會(huì)走onAuthenticationFailed()方法
        handler.obtainMessage(1,errMsgId,0).sendToTarget();
      }

      @Override
      public void onAuthenticationSucceeded(FingerprintManagerCompat.AuthenticationResult result) {
        super.onAuthenticationSucceeded(result);
        //驗(yàn)證成功時(shí)，回調(diào)該方法。fingerprint對(duì)象不能再驗(yàn)證
        handler.obtainMessage(2).sendToTarget();
      }

      @Override
      public void onAuthenticationFailed() {
        super.onAuthenticationFailed();
        //驗(yàn)證失敗時(shí)，回調(diào)該方法。fingerprint對(duì)象不能再驗(yàn)證并且需要等待一段時(shí)間才能重新創(chuàng)建指紋管理對(duì)象進(jìn)行驗(yàn)證
        handler.obtainMessage(3).sendToTarget();
      }
    };
   handler = new Handler(getMainLooper()) {  //也可以置為null,系統(tǒng)自動(dòng)處理
      @Override
      public void handleMessage(Message msg) {
      switch (msg.what) {
        case 1:  //驗(yàn)證錯(cuò)誤
           //todo 界面處理
          handleErrorCode(msg.arg1);
          break;
        case 2:  //驗(yàn)證成功
           //todo 界面處理
           cancel = null;
           break;
        case 3:  //驗(yàn)證失敗
           //todo 界面處理
           cancel = null;
           break;
        default:
          super.handleMessage(msg);
     }
     
   };
  //對(duì)應(yīng)不同的錯(cuò)誤，可以有不同的操作
  private void handleErrorCode(int code) {
    switch (code) {
      case FingerprintManager.FINGERPRINT_ERROR_CANCELED:
        //todo 指紋傳感器不可用，該操作被取消
        break;
      case FingerprintManager.FINGERPRINT_ERROR_HW_UNAVAILABLE:
        //todo 當(dāng)前設(shè)備不可用，請(qǐng)稍后再試
        break;
      case FingerprintManager.FINGERPRINT_ERROR_LOCKOUT:
        //todo 由于太多次嘗試失敗導(dǎo)致被鎖，該操作被取消
        break;
      case FingerprintManager.FINGERPRINT_ERROR_NO_SPACE:
        //todo 沒有足夠的存儲(chǔ)空間保存這次操作，該操作不能完成
        break;
      case FingerprintManager.FINGERPRINT_ERROR_TIMEOUT:
        //todo 操作時(shí)間太長(zhǎng)，一般為30秒
        break;
      case FingerprintManager.FINGERPRINT_ERROR_UNABLE_TO_PROCESS:
        //todo 傳感器不能處理當(dāng)前指紋圖片
        break;
  }
}