我在经过编辑的android应用上有此代码，但在获取特征值以在mHumidity（TextView）上设置时遇到问题。显示的值类似于android.bluetooth.BluetoothGatt@4780c之类的东西。但是从BLE设备上按下按钮后，我的期望值为0或1
/**
* Created by Dave Smith
* Double Encore, Inc.
* MainActivity
*/
public class MainActivity extends Activity implements BluetoothAdapter.LeScanCallback {
private static final String TAG = "BluetoothGattActivity";
private static final String DEVICE_NAME = "Light";
/* Humidity Service */
private static final UUID HUMIDITY_SERVICE = UUID.fromString("29e70001-9227-e097-3473-09a5cc69a43a");
private static final UUID HUMIDITY_DATA_CHAR = UUID.fromString("29e70002-9227-e097-3473-09a5cc69a43a");
private static final UUID HUMIDITY_CONFIG_CHAR = UUID.fromString("29e70003-9227-e097-3473-09a5cc69a43a");
/* Client Configuration Descriptor */
private static final UUID CONFIG_DESCRIPTOR = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
private BluetoothAdapter mBluetoothAdapter;
private SparseArray<BluetoothDevice> mDevices;
private BluetoothGatt mConnectedGatt;
private TextView mTemperature, mHumidity, mPressure;
private ProgressDialog mProgress;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setContentView(R.layout.activity_main);
setProgressBarIndeterminate(true);
/*
* We are going to display the results in some text fields
*/
// mTemperature = (TextView) findViewById(R.id.text_temperature);
mHumidity = (TextView) findViewById(R.id.text_humidity);
// mPressure = (TextView) findViewById(R.id.text_pressure);
/*
* Bluetooth in Android 4.3 is accessed via the BluetoothManager, rather than
* the old static BluetoothAdapter.getInstance()
*/
BluetoothManager manager = (BluetoothManager) getSystemService(BLUETOOTH_SERVICE);
mBluetoothAdapter = manager.getAdapter();
mDevices = new SparseArray<BluetoothDevice>();
/*
* A progress dialog will be needed while the connection process is
* taking place
*/
mProgress = new ProgressDialog(this);
mProgress.setIndeterminate(true);
mProgress.setCancelable(false);
}
@Override
protected void onResume() {
super.onResume();
/*
* We need to enforce that Bluetooth is first enabled, and take the
* user to settings to enable it if they have not done so.
*/
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
//Bluetooth is disabled
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBtIntent);
finish();
return;
}
/*
* Check for Bluetooth LE Support. In production, our manifest entry will keep this
* from installing on these devices, but this will allow test devices or other
* sideloads to report whether or not the feature exists.
*/
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "No LE Support.", Toast.LENGTH_SHORT).show();
finish();
return;
}
clearDisplayValues();
}
@Override
protected void onPause() {
super.onPause();
//Make sure dialog is hidden
mProgress.dismiss();
//Cancel any scans in progress
mHandler.removeCallbacks(mStopRunnable);
mHandler.removeCallbacks(mStartRunnable);
mBluetoothAdapter.stopLeScan(this);
}
@Override
protected void onStop() {
super.onStop();
//Disconnect from any active tag connection
if (mConnectedGatt != null) {
mConnectedGatt.disconnect();
mConnectedGatt = null;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Add the "scan" option to the menu
getMenuInflater().inflate(R.menu.main, menu);
//Add any device elements we've discovered to the overflow menu
for (int i=0; i < mDevices.size(); i++) {
BluetoothDevice device = mDevices.valueAt(i);
menu.add(0, mDevices.keyAt(i), 0, device.getName());
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_scan:
mDevices.clear();
startScan();
return true;
default:
//Obtain the discovered device to connect with
BluetoothDevice device = mDevices.get(item.getItemId());
Log.i(TAG, "Connecting to "+device.getName());
/*
* Make a connection with the device using the special LE-specific
* connectGatt() method, passing in a callback for GATT events
*/
mConnectedGatt = device.connectGatt(this, false, mGattCallback);
//Display progress UI
mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS, "Connecting to "+device.getName()+"..."));
return super.onOptionsItemSelected(item);
}
}
private void clearDisplayValues() {
//mTemperature.setText("---");
mHumidity.setText("---");
}
private Runnable mStopRunnable = new Runnable() {
@Override
public void run() {
stopScan();
}
};
private Runnable mStartRunnable = new Runnable() {
@Override
public void run() {
startScan();
}
};
private void startScan() {
mBluetoothAdapter.startLeScan(this);
setProgressBarIndeterminateVisibility(true);
mHandler.postDelayed(mStopRunnable, 2500);
}
private void stopScan() {
mBluetoothAdapter.stopLeScan(this);
setProgressBarIndeterminateVisibility(false);
}
/* BluetoothAdapter.LeScanCallback */
@Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
Log.i(TAG, "New LE Device: " + device.getName() + " @ " + rssi);
/*
* We are looking for SensorTag devices only, so validate the name
* that each device reports before adding it to our collection
*/
if (DEVICE_NAME.equals(device.getName())) {
mDevices.put(device.hashCode(), device);
//Update the overflow menu
invalidateOptionsMenu();
}
}
/*
* In this callback, we've created a bit of a state machine to enforce that only
* one characteristic be read or written at a time until all of our sensors
* are enabled and we are registered to get notifications.
*/
private BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
private void readNextSensor(BluetoothGatt gatt) {
BluetoothGattCharacteristic characteristic;
Log.d(TAG, "Reading humidity");
characteristic = gatt.getService(HUMIDITY_SERVICE).getCharacteristic(HUMIDITY_DATA_CHAR);
mHandler.sendEmptyMessage(MSG_DISMISS);
Log.i(TAG, "All Sensors Enabled");
gatt.readCharacteristic(characteristic);
}
/*
* Enable notification of changes on the data characteristic for each sensor
* by writing the ENABLE_NOTIFICATION_VALUE flag to that characteristic's
* configuration descriptor.
*/
private void setNotifyNextSensor(BluetoothGatt gatt) {
BluetoothGattCharacteristic characteristic;
Log.d(TAG, "Set notify humidity");
characteristic = gatt.getService(HUMIDITY_SERVICE).getCharacteristic(HUMIDITY_DATA_CHAR);
mHandler.sendEmptyMessage(MSG_DISMISS);
Log.i(TAG, "All Sensors Enabled");
//Enable local notifications
gatt.setCharacteristicNotification(characteristic, true);
//Enabled remote notifications
BluetoothGattDescriptor desc = characteristic.getDescriptor(CONFIG_DESCRIPTOR);
desc.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(desc);
}
/* OK */
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
Log.d(TAG, "Connection State Change: "+status+" -> "+connectionState(newState));
if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_CONNECTED) {
/*
* Once successfully connected, we must next discover all the services on the
* device before we can read and write their characteristics.
*/
gatt.discoverServices();
mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS, "Discovering Services..."));
} else if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_DISCONNECTED) {
/*
* If at any point we disconnect, send a message to clear the weather values
* out of the UI
*/
mHandler.sendEmptyMessage(MSG_CLEAR);
} else if (status != BluetoothGatt.GATT_SUCCESS) {
/*
* If there is a failure at any stage, simply disconnect
*/
gatt.disconnect();
}
}
@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
Log.d(TAG, "Services Discovered: "+status);
mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS, "Enabling Sensors..."));
/*
* With services discovered, we are going to reset our state machine and start
* working through the sensors we need to enable
*/
// enableNextSensor(gatt);
readNextSensor(gatt);
}
@Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
//For each read, pass the data up to the UI thread to update the display
if (HUMIDITY_DATA_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_HUMIDITY, characteristic));
}
//After reading the initial value, next we enable notifications
setNotifyNextSensor(gatt);
}
@Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
//After writing the enable flag, next we read the initial value
readNextSensor(gatt);
}
@Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
/*
* After notifications are enabled, all updates from the device on characteristic
* value changes will be posted here. Similar to read, we hand these up to the
* UI thread to update the display.
*/
if (HUMIDITY_DATA_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_HUMIDITY, characteristic));
}
}
@Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
//Once notifications are enabled, we move to the next sensor and start over with enable
readNextSensor(gatt);
}
@Override
public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status) {
Log.d(TAG, "Remote RSSI: "+rssi);
}
private String connectionState(int status) {
switch (status) {
case BluetoothProfile.STATE_CONNECTED:
return "Connected";
case BluetoothProfile.STATE_DISCONNECTED:
return "Disconnected";
case BluetoothProfile.STATE_CONNECTING:
return "Connecting";
case BluetoothProfile.STATE_DISCONNECTING:
return "Disconnecting";
default:
return String.valueOf(status);
}
}
};
/*
* We have a Handler to process event results on the main thread
*/
private static final int MSG_HUMIDITY = 101;
private static final int MSG_PROGRESS = 201;
private static final int MSG_DISMISS = 202;
private static final int MSG_CLEAR = 301;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
BluetoothGattCharacteristic characteristic;
switch (msg.what) {
case MSG_HUMIDITY:
characteristic = (BluetoothGattCharacteristic) msg.obj;
if (characteristic.getValue() == null) {
Log.w(TAG, "Error obtaining humidity value");
return;
}
updateHumidityValues(characteristic);
break;
case MSG_PROGRESS:
mProgress.setMessage((String) msg.obj);
if (!mProgress.isShowing()) {
mProgress.show();
}
break;
case MSG_DISMISS:
mProgress.hide();
break;
case MSG_CLEAR:
clearDisplayValues();
break;
}
}
};
/* Methods to extract sensor data and update the UI */
private void updateHumidityValues(BluetoothGattCharacteristic characteristic) {
mHumidity.setText(String.valueOf(characteristic));
}
}
// double humidity = SensorTagData.extractHumidity(characteristic);
// mHumidity.setText(String.format("%.0f%%", humidity));
最佳答案
特征的值是byte[]而不是字符串。当您执行String.valueOf（characteristicistic）时，将在堆上打印对象名称和引用，而不是实际值。
您要做的是将数组字节转换为有用的东西。这非常取决于BLE服务及其随附的特性。但是可以说，它只是一个带有值的字节。
/* Methods to extract sensor data and update the UI */
private void updateHumidityValues(BluetoothGattCharacteristic characteristic) {
short lsb = characteristic.getValue()[0] & 0xff;
mHumidity.setText(String.valueOf(lsb));
}