Android BLE- 如何在 ScanCallback 中调用 onScanResult 方法? [英] Android BLE- How is onScanResult method being called in ScanCallback?
问题描述
这是我第一次在 Android 项目中做低功耗蓝牙.我正在做的项目基本上是检测所有蓝牙 LE 设备并连接它们以发现它们的服务.
This is my first time doing Bluetooth Low Energy in Android project. The project that I am doing is basically to detect all Bluetooth LE devices and connect them to discover their services.
我想问有没有人知道在ScanCallback 中是如何调用onScanResult()、onBatchScanResults() 和onScanFailed() 方法的?
I would like to ask if anyone know how onScanResult(), onBatchScanResults() and onScanFailed() methods are being called in ScanCallback?
首先，运行 scanLeDevice() 方法.
At First, run scanLeDevice() method.
BluetoothLeScanner mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
ScanSettings settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
.setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
.build();
List<ScanFilter> filters = new ArrayList<ScanFilter>();
scanLeDevice(true);
<小时>
在这个方法中，它会开始扫描.所以我假设扫描结果是使用这些回调传递的.
In this method, it will startScan. So I assume that the scan results are delivered using these callback.
@TargetApi(21)
private void scanLeDevice(final boolean enable) {
if (enable) {
//stops scanning after a pre-defined scan period
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
System.out.println("BLE// mLEScanner.stopScan(mScanCallback) ");
mLEScanner.stopScan(mScanCallback);
}
}
}, SCAN_PERIOD);
System.out.println("BLE// mLEScanner.startScan(filters, settings, mScanCallback)");
mLEScanner.startScan(filters, settings, mScanCallback);
} else {
System.out.println("BLE// mLEScanner.stopScan(mScanCallback)");
mLEScanner.stopScan(mScanCallback);
}
}
<小时>
但是，在 ScanCallback 中，我不知道它如何触发 onScanResult 并使用回调传递扫描结果.在我的测试中(如下图所示)，既不调用 onScanResult() 也不调用 onBatchScanResults() 和 onScanFailed() .有人可以向我解释这个概念吗?对我很有帮助！
However, In ScanCallback, I have no idea how it triggers onScanResult and deliver the scan result using the callback. In my testing(as shown below), neither onScanResult() nor onBatchScanResults() and onScanFailed() be called. Can someone explain the concept to me? It will help me a lot!
/* Scan result for SDK >= 21 */
private ScanCallback mScanCallback = new ScanCallback() {
@Override
public void onScanResult(int callbackType, ScanResult result) {
System.out.println("BLE// onScanResult");
Log.i("callbackType", String.valueOf(callbackType));
Log.i("result", result.toString());
BluetoothDevice btDevice = result.getDevice();
connectToDevice(btDevice);
}
@Override
public void onBatchScanResults(List<ScanResult> results) {
System.out.println("BLE// onBatchScanResults");
for (ScanResult sr : results) {
Log.i("ScanResult - Results", sr.toString());
}
}
@Override
public void onScanFailed(int errorCode) {
System.out.println("BLE// onScanFailed");
Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
<小时>
02-17 10:38:38.513 878-895/? D/BluetoothManagerService: Added callback: android.bluetooth.IBluetoothManagerCallback$Stub$Proxy@8334cf4:true
02-17 10:38:38.520 782-782/? D/BluetoothAdapter: STATE_ON
02-17 10:38:38.529 21554-21590/? D/BtGatt.GattService: registerClient() - UUID=835342c6-81eb-4e09-9729-5bbe1c22bc86
02-17 10:38:38.529 21554-21570/? D/BtGatt.GattService: onClientRegistered() - UUID=835342c6-81eb-4e09-9729-5bbe1c22bc86, clientIf=5
02-17 10:38:38.530 782-793/? D/BluetoothLeScanner: onClientRegistered() - status=0 clientIf=5
02-17 10:38:38.530 21554-21599/? D/BtGatt.GattService: start scan with filters
02-17 10:38:38.532 782-782/? I/System.out: BLE// mLEScanner.startScan(filters, settings, mScanCallback)
02-17 10:38:38.532 21554-21573/? D/BtGatt.ScanManager: handling starting scan
02-17 10:38:38.534 21576-21577/? I/WCNSS_FILTER: ibs_msm_serial_clock_vote: vote UART CLK ON using UART driver's ioctl()
02-17 10:38:38.542 21554-21570/? D/BtGatt.GattService: onScanFilterEnableDisabled() - clientIf=5, status=0, action=1
02-17 10:38:38.543 21554-21570/? D/BtGatt.ScanManager: callback done for clientIf - 5 status - 0
02-17 10:38:38.543 21554-21573/? D/BtGatt.ScanManager: configureFilterParamter 500 10000 1 0
02-17 10:38:38.547 21554-21570/? D/BtGatt.GattService: onScanFilterParamsConfigured() - clientIf=5, status=0, action=0, availableSpace=15
02-17 10:38:38.547 21554-21570/? D/BtGatt.ScanManager: callback done for clientIf - 5 status - 0
02-17 10:38:38.548 21554-21573/? D/BtGatt.ScanManager: configureRegularScanParams() - queue=1
02-17 10:38:38.548 487-2827/? I/ACDB-LOADER: ACDB AFE returned = -19
02-17 10:38:38.549 21554-21573/? D/BtGatt.ScanManager: configureRegularScanParams() - ScanSetting Scan mode=0 mLastConfiguredScanSetting=-2147483648
02-17 10:38:38.549 21554-21573/? D/BtGatt.ScanManager: configureRegularScanParams - scanInterval = 8000configureRegularScanParams - scanWindow = 800
02-17 10:38:38.549 21554-21570/? D/BtGatt.GattService: onScanParamSetupCompleted : 0
02-17 10:38:38.568 21554-21574/? W/bt_hci: filter_incoming_event command complete event with no matching command. opcode: 0x0.
02-17 10:38:38.603 21554-21570/? D/bt_btif_gattc: btif_gattc_update_properties BLE device name=Polar HR Sensor len=15 dev_type=2
02-17 10:38:39.571 21576-21585/? I/WCNSS_FILTER: ibs_msm_serial_clock_vote: vote UART CLK OFF using UART driver's ioctl()
02-17 10:38:43.526 782-782/? I/System.out: BLE// mLEScanner.stopScan(mScanCallback)
02-17 10:38:43.599 21576-21576/? I/WCNSS_FILTER: ibs_msm_serial_clock_vote: vote UART CLK ON using UART driver's ioctl()
02-17 10:38:43.967 21576-21576/? I/WCNSS_FILTER: ibs_msm_serial_clock_vote: vote UART CLK OFF using UART driver's ioctl()
使用带有 API 23 的 Android 手机
Using Android Phone with API 23
我这里写的代码参考了:http://www.truiton.com/2015/04/android-bluetooth-low-energy-ble-example/
The code I have written here is referred to: http://www.truiton.com/2015/04/android-bluetooth-low-energy-ble-example/
[更新的代码 V1]- 不工作
[Updated Code V1]- Not working
这是我所有的代码我创建了一个虚拟外设，它处于广告模式.虚拟外设是通过名为 LightBlue 的应用程序创建的:https://itunes.apple.com/us/app/lightblue-explorer-bluetooth/id557428110?mt=8请帮我检查我的代码:)
Here is all my code I've created a virtual Peripheral and it is in advertising mode. The virtual Peripheral is created through an app called LightBlue: https://itunes.apple.com/us/app/lightblue-explorer-bluetooth/id557428110?mt=8 Please help me to check my code :)
@TargetApi(21)
public class BluetoothLE extends Fragment {
View view;
private BluetoothAdapter mBluetoothAdapter;
private int REQUEST_ENABLE_BT = 1;
private Handler mHandler;
private static final long SCAN_PERIOD = 5000; // Stops scanning after 5 seconds
private BluetoothLeScanner mLEScanner;
private BluetoothGatt mGatt; //To provide bluetooth communication
private static final int PERMISSION_REQUEST_COARSE_LOCATION = 1;
private int permissionCheck;
public BluetoothLE(){
//empty constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
view = inflater.inflate(R.layout.fragment_bluetooth, container, false);
mHandler = new Handler();
/* check if BLE is supported in this phone */
if (!getActivity().getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(getActivity(), "BLE Not Supported", Toast.LENGTH_SHORT).show();
getActivity().finish();
}
/* Enable bluetooth without leaving app */
final BluetoothManager bluetoothManager =
(BluetoothManager) getActivity().getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
/* Build ScanSetting */
ScanSettings.Builder scanSetting = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
.setReportDelay(5000);
settings = scanSetting.build();
return view;
}
@TargetApi(Build.VERSION_CODES.M)
@Override
public void onResume() {
super.onResume();
/* Ensures Bluetooth is available on the device and it is enabled. If not, displays a dialog requesting user permission to enable Bluetooth. */
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) { //Unable to obtain a BluetoothAdapter
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT); //trigger onActivityResult
} else {
if (Build.VERSION.SDK_INT >= 21) {
mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
.setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
.build();
filters = new ArrayList<ScanFilter>();
}
if(Build.VERSION.SDK_INT >= 23){
checkLocationPermission();
}
scanLeDevice(true);
}
}
@Override
public void onPause() {
super.onPause();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
scanLeDevice(false);
}
}
@Override
public void onDestroy() {
if (mGatt == null) {
return;
}
mGatt.close();
mGatt = null;
super.onDestroy();
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
System.out.println("BLE// onActivityResult");
if (requestCode == REQUEST_ENABLE_BT) {
if (resultCode == Activity.RESULT_CANCELED) {
//Bluetooth not enabled.
getActivity().finish();
return;
}
}
super.onActivityResult(requestCode, resultCode, data);
}
private void scanLeDevice(final boolean enable) {
if (enable) {
//stops scanning after a pre-defined scan period
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
if (Build.VERSION.SDK_INT < 21) {
System.out.println("BLE// mBluetoothAdapter.stopLeScan(mLeScanCallback) ");
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
System.out.println("BLE// mLEScanner.stopScan(mScanCallback) ");
}
}
}, SCAN_PERIOD);
if (Build.VERSION.SDK_INT < 21) {
System.out.println("BLE// mBluetoothAdapter.startLeScan(mLeScanCallback)");
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mLEScanner.startScan(mScanCallback);
//mLEScanner.startScan(filters, settings, mScanCallback);
System.out.println("BLE// mLEScanner.startScan(mScanCallback) ");
}
} else {
if (Build.VERSION.SDK_INT < 21) {
System.out.println("BLE// mBluetoothAdapter.stopLeScan(mLeScanCallback)");
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
System.out.println("BLE// mLEScanner.stopScan(mScanCallback)");
mLEScanner.stopScan(mScanCallback);
}
}
}
/* Scan result for SDK >= 21 */
private ScanCallback mScanCallback = new ScanCallback() {
@Override
public void onScanResult(int callbackType, ScanResult result) {
System.out.println("BLE// onScanResult");
super.onScanResult(callbackType, result);
Log.i("callbackType", String.valueOf(callbackType));
Log.i("result", result.toString());
Log.i("Device Name: ", result.getDevice().getName());
System.out.println("Signal: " + result.getRssi());
BluetoothDevice btDevice = result.getDevice();
connectToDevice(btDevice);
}
@Override
public void onBatchScanResults(List<ScanResult> results) {
System.out.println("BLE// onBatchScanResults");
for (ScanResult sr : results) {
Log.i("ScanResult - Results", sr.toString());
}
}
@Override
public void onScanFailed(int errorCode) {
System.out.println("BLE// onScanFailed");
Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
// scan results are returned here SDK < 21
private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {
@Override
public void onLeScan(final BluetoothDevice device, int rssi,
byte[] scanRecord) {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
System.out.println("BLE// DEVICDE FOUND");
Log.i("onLeScan", device.toString());
connectToDevice(device);
}
});
}
};
public void connectToDevice(BluetoothDevice device) {
System.out.println("BLE// connectToDevice()");
if (mGatt == null) {
mGatt = device.connectGatt(getActivity(), false, gattCallback); //Connect to a GATT Server
//scanLeDevice(false);// will stop after first device detection
}
}
private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
System.out.println("BLE// BluetoothGattCallback");
Log.i("onConnectionStateChange", "Status: " + status);
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
Log.i("gattCallback", "STATE_CONNECTED");
gatt.discoverServices();
break;
case BluetoothProfile.STATE_CONNECTING:
Log.i("gattCallback", "STATE_CONNECTING");
break;
case BluetoothProfile.STATE_DISCONNECTED:
Log.e("gattCallback", "STATE_DISCONNECTED");
break;
default:
Log.e("gattCallback", "STATE_OTHER");
}
}
@Override
//New services discovered
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
List<BluetoothGattService> services = gatt.getServices();
Log.i("onServicesDiscovered", services.toString());
gatt.readCharacteristic(services.get(1).getCharacteristics().get
(0));
}
@Override
//Result of a characteristic read operation
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic
characteristic, int status) {
Log.i("onCharacteristicRead", characteristic.toString());
gatt.disconnect();
}
};
public void checkLocationPermission(){
permissionCheck = ContextCompat.checkSelfPermission(getActivity(), android.Manifest.permission.ACCESS_COARSE_LOCATION);
switch(permissionCheck){
case PackageManager.PERMISSION_GRANTED:
break;
case PackageManager.PERMISSION_DENIED:
if(ActivityCompat.shouldShowRequestPermissionRationale(getActivity(), android.Manifest.permission.ACCESS_COARSE_LOCATION)){
//Show an explanation to user *asynchronouselly* -- don't block
//this thread waiting for the user's response! After user sees the explanation, try again to request the permission
Snackbar.make(view, "Location access is required to show Bluetooth devices nearby.",
Snackbar.LENGTH_LONG).setAction("Action", null).show();
}
else{
//No explanation needed, we can request the permission
ActivityCompat.requestPermissions(getActivity(), new String[]{android.Manifest.permission.ACCESS_COARSE_LOCATION}, PERMISSION_REQUEST_COARSE_LOCATION);
}
break;
}
}
}
推荐答案
我看到你在使用 public void startScan (List 方法startScan()，但您从未定义任何过滤器.相反，您传递一个空的 ScanFilters ArrayList.因此，您永远不会收到任何回调，因为您没有为过滤器提供任何匹配条件.
I see that you are using the public void startScan (List<ScanFilter> filters, ScanSettings settings, ScanCallback callback) method of startScan(), but you never define any filters. Instead, you pass an empty ArrayList of ScanFilters. So you aren't ever getting any callbacks because you aren't provided any criteria for the filters to match against.
既然您说要扫描所有 BLE 设备，则根本不需要使用任何过滤器.相反，使用更简单的 public void startScan (ScanCallback callback) 方法，该方法不使用任何过滤器或专门设置.
Since you said that you want to scan for all BLE devices, there is no need to use any filters at all. Instead, use the simpler public void startScan (ScanCallback callback) method, which doesn't use any filters or specialized settings.
关于您要求了解它是如何工作的 - 我认为根据您的代码和您对回调应该被触发的期望，您已经了解了这个概念.您开始扫描，系统关闭并在不阻止代码执行的情况下进行扫描(即它异步执行).当扫描发生时，它会在适当的时候调用回调对象中的三个方法之一(如 API 文档中所述).差不多就是这样.
Regarding your request to understand how it all works - I think you have the concept down based on your code and your expectation that the callbacks should get triggered. You start the scan, and the system goes off and does the scan without blocking your code execution (i.e. it does it asynchronously). While the scan is occurring, it will call one of the three methods in your callback object whenever appropriate (as described in the API documentation). That's pretty much it.
更新:确保您请求 BLUETOOTH、BLUETOOTH_ADMIN 权限以及 ACCESS_COARSE_LOCATION 或 ACCESS_FINE_LOCATION 权限.这些是从 startScan() 方法接收回调所必需的.不幸的是，如果您不请求这些权限，扫描只会默默地失败.我希望系统要么在日志中提供警告消息，要么触发对 onScanFailed() 方法的回调，并使用指示问题的错误代码.
UPDATE:
Make sure that you request the BLUETOOTH, BLUETOOTH_ADMIN permissions, as well as the ACCESS_COARSE_LOCATION or ACCESS_FINE_LOCATION permissions. These are required to receive callbacks from the startScan() method. Unfortunately, if you don't request those persmissions, the scan just silently fails. I would prefer if the system either provides a warning message in the logs or triggers a callback to the onScanFailed() method with the errorcode indicating the problem.
这篇关于Android BLE- 如何在 ScanCallback 中调用 onScanResult 方法?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
