Java tutorial
/* * Copyright (C) 2015 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.android.bleserver; import android.bluetooth.BluetoothAdapter; import android.bluetooth.le.BluetoothLeScanner; import android.bluetooth.le.ScanCallback; import android.bluetooth.le.ScanFilter; import android.bluetooth.le.ScanResult; import android.bluetooth.le.ScanSettings; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.ListFragment; import android.util.Log; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.Toast; import java.util.ArrayList; import java.util.List; import java.util.concurrent.TimeUnit; /** * Scans for Bluetooth Low Energy Advertisements matching a filter and displays them to the user. */ public class ScannerFragment extends ListFragment { private static final String TAG = ScannerFragment.class.getSimpleName(); /** * Stops scanning after 5 seconds. */ private static final long SCAN_PERIOD = 5000; private BluetoothAdapter mBluetoothAdapter; private BluetoothLeScanner mBluetoothLeScanner; private ScanCallback mScanCallback; private ScanResultAdapter mAdapter; private Handler mHandler; /** * Must be called after object creation by MainActivity. * * @param btAdapter the local BluetoothAdapter */ public void setBluetoothAdapter(BluetoothAdapter btAdapter) { this.mBluetoothAdapter = btAdapter; mBluetoothLeScanner = mBluetoothAdapter.getBluetoothLeScanner(); } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); setRetainInstance(true); // Use getActivity().getApplicationContext() instead of just getActivity() because this // object lives in a fragment and needs to be kept separate from the Activity lifecycle. // // We could get a LayoutInflater from the ApplicationContext but it messes with the // default theme, so generate it from getActivity() and pass it in separately. mAdapter = new ScanResultAdapter(getActivity().getApplicationContext(), LayoutInflater.from(getActivity())); mHandler = new Handler(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { final View view = super.onCreateView(inflater, container, savedInstanceState); setListAdapter(mAdapter); return view; } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); getListView().setDivider(null); getListView().setDividerHeight(0); setEmptyText(getString(R.string.empty_list)); // Trigger refresh on app's 1st load startScanning(); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { super.onCreateOptionsMenu(menu, inflater); inflater.inflate(R.menu.scanner_menu, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.refresh: startScanning(); return true; default: return super.onOptionsItemSelected(item); } } /** * Start scanning for BLE Advertisements (& set it up to stop after a set period of time). */ public void startScanning() { if (mScanCallback == null) { Log.d(TAG, "Starting Scanning"); // Will stop the scanning after a set time. mHandler.postDelayed(new Runnable() { @Override public void run() { stopScanning(); } }, SCAN_PERIOD); // Kick off a new scan. mScanCallback = new SampleScanCallback(); mBluetoothLeScanner.startScan(buildScanFilters(), buildScanSettings(), mScanCallback); String toastText = getString(R.string.scan_start_toast) + " " + TimeUnit.SECONDS.convert(SCAN_PERIOD, TimeUnit.MILLISECONDS) + " " + getString(R.string.seconds); Toast.makeText(getActivity(), toastText, Toast.LENGTH_LONG).show(); } else { Toast.makeText(getActivity(), R.string.already_scanning, Toast.LENGTH_SHORT); } } /** * Stop scanning for BLE Advertisements. */ public void stopScanning() { Log.d(TAG, "Stopping Scanning"); // Stop the scan, wipe the callback. mBluetoothLeScanner.stopScan(mScanCallback); mScanCallback = null; // Even if no new results, update 'last seen' times. mAdapter.notifyDataSetChanged(); } /** * Return a List of {@link ScanFilter} objects to filter by Service UUID. */ private List<ScanFilter> buildScanFilters() { List<ScanFilter> scanFilters = new ArrayList<>(); ScanFilter.Builder builder = new ScanFilter.Builder(); // Comment out the below line to see all BLE devices around you builder.setServiceUuid(Constants.Service_UUID); scanFilters.add(builder.build()); return scanFilters; } /** * Return a {@link ScanSettings} object set to use low power (to preserve battery life). */ private ScanSettings buildScanSettings() { ScanSettings.Builder builder = new ScanSettings.Builder(); builder.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER); return builder.build(); } /** * Custom ScanCallback object - adds to adapter on success, displays error on failure. */ private class SampleScanCallback extends ScanCallback { @Override public void onBatchScanResults(List<ScanResult> results) { super.onBatchScanResults(results); for (ScanResult result : results) { mAdapter.add(result); } mAdapter.notifyDataSetChanged(); } @Override public void onScanResult(int callbackType, ScanResult result) { super.onScanResult(callbackType, result); mAdapter.add(result); mAdapter.notifyDataSetChanged(); } @Override public void onScanFailed(int errorCode) { super.onScanFailed(errorCode); Toast.makeText(getActivity(), "Scan failed with error: " + errorCode, Toast.LENGTH_LONG).show(); } } }