我正在尝试连接外围设备。当我在Scancallback中找到我想要的设备时，我将设备的消息发送给我的处理程序。
11-16 10:31:12.471 25907-25907/I/BleManager: START SCAN
11-16 10:31:12.471 25907-25907/ D/BluetoothAdapter: startLeScan(): null
11-16 10:31:12.481 25907-25918/ D/BluetoothAdapter: onClientRegistered() - status=0 clientIf=5
11-16 10:31:12.731 25907-25918/ W/BleOlderScanCallback: Try to connect device
11-16 10:31:12.731 25907-25907/ I/BleManager: STOP SCAN
11-16 10:31:12.731 25907-25907/ D/BluetoothAdapter: stopLeScan()
11-16 10:31:12.741 25907-25907/ I/BleManager: connect device
11-16 10:31:12.741 25907-25907/ I/Runnable: connectGatt
11-16 10:31:12.741 25907-25907/ D/BluetoothGatt: connect() - device: [hidden], auto: false
11-16 10:31:12.741 25907-25907/ D/BluetoothGatt: registerApp()
11-16 10:31:12.741 25907-25907/ D/BluetoothGatt: registerApp() - UUID=[hidden]
11-16 10:31:12.751 25907-25919/ D/BluetoothGatt: onClientRegistered() - status=0 clientIf=5
11-16 10:31:15.441 25907-25918/ D/BluetoothGatt: onClientConnectionState() - status=0 clientIf=5 device=[hidden]
11-16 10:31:15.441 25907-25918/ W/BluetoothGatt: Unhandled exception in callback java.lang.NullPointerException
at android.bluetooth.BluetoothGatt$1.onClientConnectionState(BluetoothGatt.java:168)
at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:71)
at android.os.Binder.execTransact(Binder.java:404)
at dalvik.system.NativeStart.run(Native Method)
这是我的代码：
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
public class BleOlderScanCallback implements BluetoothAdapter.LeScanCallback {
private static final String TAG = BleOlderScanCallback.class.getSimpleName();
private static final int START_BYTE_I = 2;
private static final int MAC_BYTE_I = 7;
private static final int MAC_SIZE = 6;
private Handler handler;
private String mac;
public BleOlderScanCallback(Handler handler, String mac) {
this.handler = handler;
this.mac = mac;
}
protected void onResult(BluetoothDevice device, byte[] scanRecord){
byte[] macBytes;
String mac;
if (device != null && scanRecord != null) {
macBytes = new byte[MAC_SIZE];
System.arraycopy(scanRecord, MAC_BYTE_I, macBytes, 0, MAC_SIZE); // copy MAC_SIZE positions (since index MAC_BYTE_I) of array scanRecord to array mac
mac = formatMAC(macBytes);
Logg.i(TAG, mac + " device: " + device.getName());
if (this.mac.equals(mac)) {
Logg.w(TAG, "Try to connect device");
handler.obtainMessage(BleHandler.SCANNED_DEVICE, device).sendToTarget();
}
else{
Logg.i(TAG, "Other mac ");
}
}
}
/**
* API lower Lollipop (21)
* @param device
* @param rssi
* @param scanRecord
*/
@Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
onResult(device, scanRecord);
}
}
这是我的经纪人。它调用我的经理类来连接BluetoothGatt
public class BleHandler extends Handler {
private static final String TAG = BleHandler.class.getSimpleName();
public static final int SCANNED_DEVICE = 1;
private BleManager bleManager; // should I use WeakReference?
public BleHandler (BleManager bleManager){
this.bleManager = bleManager;
}
@Override
public void handleMessage(Message message){
BluetoothDevice device;
switch (message.what){
case SCANNED_DEVICE:
bleManager.stopBtScan();
device = (BluetoothDevice) message.obj;
bleManager.connect(device);
break;
}
}
}
在我的经理类中，connect方法如下所示：
public void connect(final BluetoothDevice device){
Logg.i(TAG, "connect device");
if (device == null){
Logg.i(TAG, "device to connect is null");
return;
}
Handler handler = new Handler(context.getMainLooper());
handler.post(new Runnable() {
@Override
public void run() {
Logg.i("Runnable", "connectGatt");
bluetoothGatt = device.connectGatt(context, false, bluetoothGattCallback);
}
});
}
我覆盖了BluetoothGatt.onConnectionStateChange，但执行不会到达
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
public class BleGattCallback extends BluetoothGattCallback {
private static final String TAG = BleGattCallback.class.getSimpleName();
private int connectionState = STATE_DISCONNECTED;
protected static final int STATE_DISCONNECTED = 0;
protected static final int STATE_CONNECTING = 1;
protected static final int STATE_CONNECTED = 2;
// public static final String ACTION_GATT_CONNECTED = "com.example.bluetooth.le.ACTION_GATT_CONNECTED";
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status,
int newState) {
Logg.i(TAG, "onConnectionStateChange");
try {
super.onConnectionStateChange(gatt, status, newState);
if (newState == BluetoothProfile.STATE_CONNECTED) {
connectionState = STATE_CONNECTED;
Logg.w(TAG, "Connected to GATT server");
Logg.i(TAG, "Attempting to start service discovery:" + gatt.discoverServices());
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
connectionState = STATE_DISCONNECTED;
Logg.w(TAG, "Disconnected from GATT server.");
try {
gatt.close();
} catch (Exception e) {
Logg.d(TAG, "close ignoring: " + e);
}
}
}catch(NullPointerException e){
Logg.i(TAG, "NullPointerException onConnectionStateChange");
}
}
}
我在stackoverflow中看到这里尝试断开时出现了类似的错误，并且解决方案是在gatt.disconnect之后没有调用gatt.close（），但这是一个不同的问题，我无法解决它。我使用蓝牙LE进行了新的编程，并且陷入了这一部分。
答案 0 :(得分：0)
尝试像这样做回调：
// Various callback methods defined by the BLE API.
private final BluetoothGattCallback mGattCallback =
new BluetoothGattCallback() {
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status,
int newState) {
String intentAction;
if (newState == BluetoothProfile.STATE_CONNECTED) {
intentAction = ACTION_GATT_CONNECTED;
mConnectionState = STATE_CONNECTED;
broadcastUpdate(intentAction);
Log.i(TAG, "Connected to GATT server.");
Log.i(TAG, "Attempting to start service discovery:" +
mBluetoothGatt.discoverServices());
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
intentAction = ACTION_GATT_DISCONNECTED;
mConnectionState = STATE_DISCONNECTED;
Log.i(TAG, "Disconnected from GATT server.");
broadcastUpdate(intentAction);
}
}
}
来源：https://developer.android.com/guide/topics/connectivity/bluetooth-le.html
并确保保留BluetoothGatt bluetoothGatt。如果将null写入其中，则不再调用回调。也许这解决了你的问题。
答案 1 :(得分：0)
我刚发现了这个问题。这是一个愚蠢的事情，我使用null bluetoothGattCallback调用device.connect。写这个问题对我来说真的很有帮助，我在这个问题上是一个难忘的日子。