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我在新的nexus 7（4.3 JSS15R）上使用蓝牙示例（android-sdks/samples/android-18/legacy/BluetoothLeGatt/）来测试蓝牙。而且我发现 readCharacteristic 花费了太多时间（每次读取大约 1 ~ 3 秒）。

首先，我在单击服务项时触发 readCharacteristic。

    DeviceControlActivity.java
    ....
    private final ExpandableListView.OnChildClickListener servicesListClickListner = 
    ....
    public boolean onChildClick(ExpandableListView parent, View v, int groupPosition,
    ....
         mBluetoothLeService.readCharacteristic(characteristic);

然后我在读取特征时重复 readCharacteristic。

    BluetoothLeService.java
    ....
    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
    ....
    @Override
    public void onCharacteristicRead(BluetoothGatt gatt,
                                     BluetoothGattCharacteristic characteristic,
                                     int status) {
        if(TEST_COUNT < 20) {
            Log.d(TAG,"onCharacteristicRead");
            readCharacteristic(characteristic);
            TEST_COUNT ++; 
        } else {
            TEST_COUNT = 0;
        }   

        /*  
        if (status == BluetoothGatt.GATT_SUCCESS) {
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
        }
        */
    }

日志显示：

10-29 11:16:37.360: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:39.362: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:41.364: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:43.356: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:45.358: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:47.340: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:49.342: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:51.334: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:53.336: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:55.328: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:57.319: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:16:59.311: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:01.313: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:03.305: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:05.297: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:07.289: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:09.291: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:11.283: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:13.285: DEBUG/MyTest(9554): onCharacteristicRead
10-29 11:17:15.277: DEBUG/MyTest(9554): onCharacteristicRead

接收每个特征读取需要 2 秒，真的很奇怪。

我使用三星 ble sdk 和相同的 ble 设备在 Galaxy s4 上测试了相同的行为。但是日志显示它花费更少的时间阅读。

10-29 11:51:19.393  I/MyTest﹕  onCharacteristicRead
10-29 11:51:19.493  I/MyTest﹕  onCharacteristicRead
10-29 11:51:19.588  I/MyTest﹕  onCharacteristicRead
10-29 11:51:19.688  I/MyTest﹕  onCharacteristicRead
10-29 11:51:19.783  I/MyTest﹕  onCharacteristicRead
10-29 11:51:19.878  I/MyTest﹕  onCharacteristicRead
10-29 11:51:19.978  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.078  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.183  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.323  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.418  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.518  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.613  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.713  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.808  I/MyTest﹕  onCharacteristicRead
10-29 11:51:20.908  I/MyTest﹕  onCharacteristicRead
10-29 11:51:21.003  I/MyTest﹕  onCharacteristicRead
10-29 11:51:21.103  I/MyTest﹕  onCharacteristicRead
10-29 11:51:21.248  I/MyTest﹕  onCharacteristicRead
10-29 11:51:21.343  I/MyTest﹕  onCharacteristicRead
10-29 11:51:21.443  I/MyTest﹕  onCharacteristicRead

有人遇到同样的问题吗？它是由新的nexus 7硬件引起的吗？还是安卓 4.3 sdk？

我应该怎么做才能减少花在 readCharacteristic 上的时间？

4

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