DragonKeyboardFirmwareUpdater/dfu/src/no/nordicsemi/android/dfu/internal/scanner/BootloaderScannerLollipop.java

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package no.nordicsemi.android.dfu.internal.scanner;

import android.annotation.TargetApi;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.le.BluetoothLeScanner;
import android.bluetooth.le.ScanCallback;
import android.bluetooth.le.ScanResult;
import android.bluetooth.le.ScanSettings;
import android.os.Build;

/**
 * @see BootloaderScanner
 */
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public class BootloaderScannerLollipop extends ScanCallback implements BootloaderScanner {
	private final Object mLock = new Object();
	private String mDeviceAddress;
	private String mDeviceAddressIncremented;
	private String mBootloaderAddress;
	private boolean mFound;

	@Override
	public String searchFor(final String deviceAddress) {
		final String firstBytes = deviceAddress.substring(0, 15);
		final String lastByte = deviceAddress.substring(15); // assuming that the device address is correct
		final String lastByteIncremented = String.format("%02X", (Integer.valueOf(lastByte, 16) + ADDRESS_DIFF) & 0xFF);

		mDeviceAddress = deviceAddress;
		mDeviceAddressIncremented = firstBytes + lastByteIncremented;
		mBootloaderAddress = null;
		mFound = false;

		// Add timeout
		new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					Thread.sleep(BootloaderScanner.TIMEOUT);
				} catch (final InterruptedException e) {
					// do nothing
				}

				if (mFound)
					return;

				mBootloaderAddress = null;
				mFound = true;

				// Notify the waiting thread
				synchronized (mLock) {
					mLock.notifyAll();
				}
			}
		}, "Scanner timer").start();

		final BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
		final BluetoothLeScanner scanner = adapter.getBluetoothLeScanner();
		/*
		 * Scanning with filters does not work on Nexus 9 (Android 5.1). No devices are found and scanner terminates on timeout.
		 * We will match the device address in the callback method instead. It's not like it should be, but at least it works.
		 */
		//final List<ScanFilter> filters = new ArrayList<>();
		//filters.add(new ScanFilter.Builder().setDeviceAddress(mDeviceAddress).build());
		//filters.add(new ScanFilter.Builder().setDeviceAddress(mDeviceAddressIncremented).build());
		final ScanSettings settings = new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY).build();
		scanner.startScan(/*filters*/ null, settings, this);

		try {
			synchronized (mLock) {
				while (!mFound)
					mLock.wait();
			}
		} catch (final InterruptedException e) {
			// do nothing
		}

		scanner.stopScan(this);
		return mBootloaderAddress;
	}

	@Override
	public void onScanResult(final int callbackType, final ScanResult result) {
		final String address = result.getDevice().getAddress();

		if (mDeviceAddress.equals(address) || mDeviceAddressIncremented.equals(address)) {
			mBootloaderAddress = address;
			mFound = true;

			// Notify the waiting thread
			synchronized (mLock) {
				mLock.notifyAll();
			}
		}
	}
}