android - 如何通过蓝牙低功耗 (BLE) 链路发送数据？

Question

我能够发现，连接到蓝牙。

源代码---

通过蓝牙连接到远程设备:

//Get the device by its serial number
 bdDevice = mBluetoothAdapter.getRemoteDevice(blackBox);

 //for ble connection
 bdDevice.connectGatt(getApplicationContext(), true, mGattCallback);

Gatt 状态回调:

 private BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
    //Connection established
    if (status == BluetoothGatt.GATT_SUCCESS
        && newState == BluetoothProfile.STATE_CONNECTED) {

        //Discover services
        gatt.discoverServices();

    } else if (status == BluetoothGatt.GATT_SUCCESS
        && newState == BluetoothProfile.STATE_DISCONNECTED) {

        //Handle a disconnect event

    }
    }

    @Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status) {

    //Now we can start reading/writing characteristics

    }
};

现在我想向远程 BLE 设备发送命令，但不知道该怎么做。

一旦命令发送到 BLE 设备，BLE 设备将通过广播进行响应我的应用程序可以接收的数据。

Answer 1

当您连接到 BLE 设备并发现服务时，您需要将此过程分解为几个步骤:

1. 在 onServicesDiscovered 中为您的 callback 显示可用的 gattServices

2. 检查是否可以写一个特征
   检查 BluetoothGattCharacteristic PROPERTIES - 我没有意识到需要在 BLE 硬件上启用 PROPERTY_WRITE，这浪费了很多时间。

3. 当你编写一个特性时，硬件是否会执行任何操作来明确指示该操作(在我的情况下，我正在点亮一个 LED)

假设 mWriteCharacteristic 是 BluetoothGattCharacteristic检查属性的部分应该是这样的:

if (((characteristic.getProperties() & BluetoothGattCharacteristic.PROPERTY_WRITE) |
     (charaProp & BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE)) > 0) {
 // writing characteristic functions
 mWriteCharacteristic = characteristic;
  }

并且，写下你的特点:

// "str" is the string or character you want to write
byte[] strBytes = str.getBytes();
byte[] bytes = activity.mWriteCharacteristic.getValue();  
YourActivity.this.mWriteCharacteristic.setValue(bytes);
YourActivity.this.writeCharacteristic(YourActivity.this.mWriteCharacteristic);  

这些是您需要精确实现的代码中有用的部分。

请参阅 this github project仅包含基本演示的实现。