안드로이드 지문 체크 하기

체크 리스트앱에 비밀번호를 설정해서 쓰는데, 매번 숫자 쳐넣기가 귀찮아서 OS에 등록한 지문을 체크하도록 개선 했다. 

지문은 안드로이드 6.0 Api 23(마시멜로) 부터 사용가능하다. 

https://github.com/googlesamples/android-FingerprintDialog/blob/master/Application/src/main/java/com/example/android/fingerprintdialog/FingerprintUiHelper.java 참고해서 

FingerprintUiHelper.kt를 구현

typealias FingerprintUiHelperCallback = () -> Unit

@TargetApi(Build.VERSION_CODES.M)
class FingerprintUiHelper(
    private val fingerprintManager: FingerprintManager?,
    private val icon: ImageView,
    private val errorTextView: TextView
) : FingerprintManager.AuthenticationCallback() {

    companion object {
        private const val ERROR_TIMEOUT_MILLIS: Long = 1600
    }

    private var cancellationSignal: CancellationSignal? = null
    private var selfCancelled: Boolean = false
    private val isFingerprintAuthAvailable: Boolean
        get() = fingerprintManager?.isHardwareDetected == true && fingerprintManager.hasEnrolledFingerprints()

    private var resetErrorTextRunnable: Runnable = Runnable {
        errorTextView.text = errorTextView.resources.getString(R.string.fingerprint_hint)
        icon.setImageResource(R.drawable.ic_fp_40px)
    }

    var onAuthenticatedCallback: FingerprintUiHelperCallback = {}
    var onErrorCallback: FingerprintUiHelperCallback = {}

    fun startListening(): Boolean {
        if (!isFingerprintAuthAvailable) {
            return false
        }
        cancellationSignal = CancellationSignal()
        selfCancelled = false
        fingerprintManager
            ?.authenticate(null, cancellationSignal, 0 /* flags */, this, null)
        icon.setImageResource(R.drawable.ic_fp_40px)

        return true
    }

    fun stopListening() {
        if (cancellationSignal != null) {
            selfCancelled = true
            cancellationSignal!!.cancel()
            cancellationSignal = null
        }
    }

    override fun onAuthenticationError(errMsgId: Int, errString: CharSequence) {
        if (!selfCancelled) {
            showError(errString)
            icon.postDelayed({ onErrorCallback() }, ERROR_TIMEOUT_MILLIS)
        }
    }

    override fun onAuthenticationHelp(helpMsgId: Int, helpString: CharSequence) {
        showError(helpString)
    }

    override fun onAuthenticationFailed() {
        showError(
            icon.resources.getString(
                R.string.fingerprint_not_recognized
            )
        )
    }

    override fun onAuthenticationSucceeded(result: FingerprintManager.AuthenticationResult) {
        errorTextView.removeCallbacks(resetErrorTextRunnable)
        icon.setImageResource(R.drawable.ic_fingerprint_success)
        errorTextView.text = errorTextView.resources.getString(R.string.fingerprint_success)
        onAuthenticatedCallback()
    }

    private fun showError(error: CharSequence) {
        icon.setImageResource(R.drawable.ic_fingerprint_error)
        errorTextView.text = error
        errorTextView.removeCallbacks(resetErrorTextRunnable)
        errorTextView.postDelayed(resetErrorTextRunnable, ERROR_TIMEOUT_MILLIS)
    }
}

리소스나 스트링은 github을 참고하면 되기에 생략한다.

지문을 체크하는 View를 하나 만든다. 지문 체크 페이지의 특정 viewGroup에 addView하여 지문 기능을 Injection한다.

FingerprintAuthView.kt

@TargetApi(Build.VERSION_CODES.M)
class FingerprintAuthView @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0,
    defStyleRes: Int = 0
) : LinearLayout(context, attrs, defStyleAttr, defStyleRes) {

    private var fingerprintUiHelper: FingerprintUiHelper
    private var layout: View = LayoutInflater.from(context).inflate(R.layout.fingerprint_auth_view, null)

    init {
        fingerprintUiHelper = FingerprintUiHelper(
            context.getSystemService(FingerprintManager::class.java),
            layout.findViewById(R.id.passcode_fingerprint_image),
            layout.findViewById(R.id.passcode_fingerprint_status)
        )
        addView(
            layout,
            LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT)
        )
        layout.visibility = View.GONE
    }

    override fun onAttachedToWindow() {
        super.onAttachedToWindow()
        val isStarted = fingerprintUiHelper.startListening()
        layout.visibility = if (isStarted) View.VISIBLE else View.GONE
    }

    override fun onDetachedFromWindow() {
        super.onDetachedFromWindow()
        fingerprintUiHelper.stopListening()
    }

    fun setOnAuthenticated(callback: FingerprintUiHelperCallback) {
        fingerprintUiHelper.onAuthenticatedCallback = callback;
    }

    fun setOnError(callback: FingerprintUiHelperCallback) {
        fingerprintUiHelper.onErrorCallback = callback
    }
}

AuthView를 injection해보자. 

PassCodeActivity.java

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M
        && mMode == PassCodeMode.Confirm) {
    LinearLayout linearLayout = findViewById(R.id.linearLayout1);
    FingerprintAuthView authView = new FingerprintAuthView(this);
    authView.setOnAuthenticated(new Function0<Unit>() {
        @Override
        public Unit invoke() {
            finish();
            return null;
        }
    });
    linearLayout.addView(authView);
}

권한 추가도 잊지말것

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