高通平台 android7.1 蓝牙的可见性设置

1、情景

        本机设备只打开蓝牙开关，但不停留在设置里面蓝牙页面时，其他设备扫描不到本机设备。

2、Android7.1中，默认的行为是，只有在设置里面的蓝牙页面，才会开启蓝牙的可见性；如果只是打开下拉栏的蓝牙快捷开关，是不会开启蓝牙可见性的。

3、需求：

        （1）打开蓝牙时，直接打开蓝牙可见性

        （2）不停留在设置里面蓝牙页面时，要扫描到本机设备

4、需求一的解决方案：

        打开蓝牙时，直接打开蓝牙可见性。如下：

路径：****/packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterProperties.java

void onBluetoothReady() {
        Log.d(TAG, "ScanMode =  " + mScanMode );
        Log.d(TAG, "State =  " + getState() );

        // When BT is being turned on, all adapter properties will be sent in 1
        // callback. At this stage, set the scan mode.
        synchronized (mObject) {
            if (getState() == BluetoothAdapter.STATE_TURNING_ON &&
                    mScanMode == BluetoothAdapter.SCAN_MODE_NONE) {
                    /* mDiscoverableTimeout is part of the
                       adapterPropertyChangedCallback received before
                       onBluetoothReady */
                    if (mDiscoverableTimeout != 0)
					  //setScanMode(AbstractionLayer.BT_SCAN_MODE_CONNECTABLE);
                      setScanMode(AbstractionLayer.BT_SCAN_MODE_CONNECTABLE_DISCOVERABLE);
                    else /* if timeout == never (0) at startup */
                      setScanMode(AbstractionLayer.BT_SCAN_MODE_CONNECTABLE_DISCOVERABLE);
                    /* though not always required, this keeps NV up-to date on first-boot after flash */
                    setDiscoverableTimeout(mDiscoverableTimeout);
            }
        }
    }

    如上图：    将  setScanMode(AbstractionLayer.BT_SCAN_MODE_CONNECTABLE);  改为

        setScanMode(AbstractionLayer.BT_SCAN_MODE_CONNECTABLE_DISCOVERABLE);即可。

5、需求二的解决方案，如下：

路径：******/packages/apps/Settings/src/com/android/settings/bluetooth/BluetoothSettings.java

@Override
    public void onPause() {
        super.onPause();
        if (mBluetoothEnabler != null) {
            mBluetoothEnabler.pause();
        }

        // Make the device only visible to connected devices.
        //mLocalAdapter.setScanMode(BluetoothAdapter.SCAN_MODE_CONNECTABLE);

        if (isUiRestricted()) {
            return;
        }

        getActivity().unregisterReceiver(mReceiver);
    }

如上图，在onPause()方法中将mLocalAdapter.setScanMode(BluetoothAdapter.SCAN_MODE_CONNECTABLE);注释掉即可。