我是Android和蓝牙新手并且遇到了这个问题。
如果触摸了两个按钮，我想写一个特定的特征。 如果我触摸第一个按钮，0-9之间的数字应该计为+1。使用另一个按钮时，数字应减少为-1。 作为一个基础，我使用了谷歌的BluetootleGatt示例应用程序。 在DeviceControlActivity中，我更改了以下代码：
private final ExpandableListView.OnChildClickListener servicesListClickListner =
new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition,
int childPosition, long id) {
if (mGattCharacteristics != null) {
final BluetoothGattCharacteristic characteristic =
mGattCharacteristics.get(groupPosition).get(childPosition);
final int charaProp = characteristic.getProperties(); //The properties contain a bit mask of property flags indicating
//the features of this characteristic.
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_READ) > 0) {
// If there is an active notification on a characteristic, clear
// it first so it doesn't update the data field on the user interface.
if (mNotifyCharacteristic != null) {
mBluetoothLeService.setCharacteristicNotification(
mNotifyCharacteristic, false);
mNotifyCharacteristic = null;
}
mBluetoothLeService.readCharacteristic(characteristic);
}
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_NOTIFY ) > 0) {
mNotifyCharacteristic = characteristic;
mBluetoothLeService.setCharacteristicNotification(
characteristic, true);
}
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_WRITE) > 0) {
characteristic.setWriteType(BluetoothGattCharacteristic.PERMISSION_WRITE);
addListenerOnButton();
}
return true;
}
return false;
}
};
这是两个按钮的addListenerOnButton（）：
public void addListenerOnButton() {
mArrowUp = (ImageButton) findViewById(R.id.arrow_up);
mArrowUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
mBluetoothLeService.writeCharacteristicUp();
}
});
mArrowDown = (ImageButton) findViewById(R.id.arrow_down);
mArrowDown.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
mBluetoothLeService.writeCharacteristicDown();
}
});
}
他们将调用BluetoothLeService-Class中的两个writeCharacteristic方法。例如，我在这里只发布了writeCharacteristicUp（） - 方法：
public boolean writeCharacteristicUp() {
//check mBluetoothGatt is available
if (mBluetoothGatt == null) {
Log.e(TAG, "lost connection");
return false;
}
BluetoothGattService Service = mBluetoothGatt.getService(UUID_DO_LOGGER_TEST);
if (Service == null) {
Log.e(TAG, "service not found!");
return false;
}
BluetoothGattCharacteristic charac = Service
.getCharacteristic(UUID_TEST_NUMBER);
if (charac == null) {
Log.e(TAG, "char not found!");
return false;
}
byte[] value0 = new byte[1];
value0[0] = (byte) 0; //Constant of 0 for comparison later
byte[] value1 = new byte[1];
value1[0] = (byte) 1; //Constant of 1 for comparison later
byte[] value2 = new byte[1];
value2[0] = (byte) 2; //Constant of 1 for comparison later
byte[] value3 = new byte[1];
value3[0] = (byte) 3; //Constant of 1 for comparison later
byte[] value4 = new byte[1];
value4[0] = (byte) 4; //Constant of 1 for comparison later
byte[] value5 = new byte[1];
value5[0] = (byte) 5; //Constant of 1 for comparison later
byte[] value6 = new byte[1];
value6[0] = (byte) 6; //Constant of 1 for comparison later
byte[] value7 = new byte[1];
value7[0] = (byte) 7; //Constant of 1 for comparison later
byte[] value8 = new byte[1];
value8[0] = (byte) 8; //Constant of 1 for comparison later
byte[] value9 = new byte[1];
value9[0] = (byte) 9; //Constant of 1 for comparison later
byte[] actualvalue = charac.getValue();
if (actualvalue == value0) {
charac.setValue(value1);
}
if (actualvalue == value1) {
charac.setValue(value2);
}
if (actualvalue == value2) {
charac.setValue(value3);
}
if (actualvalue == value3) {
charac.setValue(value4);
}
if (actualvalue == value4) {
charac.setValue(value5);
}
if (actualvalue == value5) {
charac.setValue(value6);
}
if (actualvalue == value6) {
charac.setValue(value7);
}
if (actualvalue == value7) {
charac.setValue(value8);
}
if (actualvalue == value8) {
charac.setValue(value9);
}
if (actualvalue == value9) {
charac.setValue(value0);
}
// charac.setValue(value0);
// byte[] actualvaluenew1 = charac.getValue();
boolean status = mBluetoothGatt.writeCharacteristic(charac);
// byte[] actualvaluenew2 = charac.getValue();
return status;
}
问题在于
boolean status = mBluetoothGatt.writeCharacteristic(charac)
不起作用，状态为false。因此，实际值不会显示在相应TextView的屏幕上。为什么？ 另外我发现if-grinds没有工作，因为charac.setValue（value0）只在if-grinds之外工作？
答案 0 :(得分：0)
我建议您按住 control 键并单击代码中的BluetoothGatt#writeCharacteristic(ch)功能。然后Android Studio将查看BluetoothGatt#writeCharacteristic(BluetoothGattCharacteristic characteristic)功能：
public boolean writeCharacteristic(BluetoothGattCharacteristic characteristic) {
if ((characteristic.getProperties() & BluetoothGattCharacteristic.PROPERTY_WRITE) == 0
&& (characteristic.getProperties() &
BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE) == 0) return false;
if (VDBG) Log.d(TAG, "writeCharacteristic() - uuid: " + characteristic.getUuid());
if (mService == null || mClientIf == 0 || characteristic.getValue() == null) return false;
BluetoothGattService service = characteristic.getService();
if (service == null) return false;
BluetoothDevice device = service.getDevice();
if (device == null) return false;
synchronized(mDeviceBusy) {
if (mDeviceBusy) return false;
mDeviceBusy = true;
}
try {
mService.writeCharacteristic(mClientIf, device.getAddress(),
service.getType(), service.getInstanceId(),
new ParcelUuid(service.getUuid()), characteristic.getInstanceId(),
new ParcelUuid(characteristic.getUuid()),
characteristic.getWriteType(), AUTHENTICATION_NONE,
characteristic.getValue());
} catch (RemoteException e) {
Log.e(TAG,"",e);
mDeviceBusy = false;
return false;
}
return true;
}
在方法中放置一个断点并进行调试。以下是您根据源代码获取false的可能原因：
在我看来，最有可能的第二项是原因。