如何用C#在PC上查找连接蓝牙设备并实现数据传输

一、前言

本文将会详细介绍如何使用C#语言在PC上实现蓝牙设备的搜索与数据传输。在使用之前我们需要先安装对应的.net Framework和Win32 API支持库文件。

二、搜索蓝牙设备
1. 使用WMI查找
我们可以使用WMI对象获取当前计算机中的所有蓝牙设备并进行遍历。搜索蓝牙设备可以通过以下代码实现：

ManagementObjectSearcher searcher = new ManagementObjectSearcher("select * from Win32_PnPEntity where DeviceID like '%_VID_%%%' or DeviceID like '%_vid_%%%'");
foreach (ManagementObject device in searcher.Get())
{
    String HardwareID = (string[])device["HardwareID"] ?? new string[0];
    if (HardwareID.Length < 1)
        continue;

    if (HardwareID[0].ToLower().Contains("vid_0489")) //根据蓝牙设备的厂家VID判断是否为蓝牙设备
    {
        String id = (string)device["PNPDeviceID"];
    }
}

1. 使用API查找
   除了WMI，我们还可以通过Win32 API函数来进行查找蓝牙设备。其中主要的API有BluetoothFindFirstRadio和BluetoothFindNextRadio函数。搜索蓝牙设备可以通过以下代码实现：

public static Guid BLUETOOTH_DEVICE_GUID = new Guid("00001101-0000-1000-8000-00805F9B34FB");
public static Guid BLUETOOTH_SERVICE_BROWSE_GUID = new Guid("{00000000-0000-0000-0000-000000000000}");

[DllImport("BluetoothAPIs.dll", SetLastError = true)]
public static extern IntPtr BluetoothFindFirstRadio(ref BLUETOOTH_FIND_RADIO_PARAMS pbtfrp, ref IntPtr phRadio);

[DllImport("BluetoothAPIs.dll", SetLastError = true)]
public static extern bool BluetoothFindNextRadio(IntPtr hFind, ref IntPtr phRadio);

[DllImport("BluetoothAPIs.dll", SetLastError = true)]
public static extern bool BluetoothFindDeviceClose(IntPtr hFind);

[DllImport("BluetoothAPIs.dll", SetLastError = true)]
public static extern IntPtr BluetoothFindFirstDevice(ref BLUETOOTH_DEVICE_SEARCH_PARAMS pbtsp, ref BLUETOOTH_DEVICE_INFO pbtdi);

[DllImport("BluetoothAPIs.dll", SetLastError = true)]
public static extern bool BluetoothFindNextDevice(IntPtr hFind, ref BLUETOOTH_DEVICE_INFO pbtdi);

[DllImport("BluetoothAPIs.dll", SetLastError = true)]
public static extern bool BluetoothSetServiceState(IntPtr hRadio, ref BLUETOOTH_DEVICE_INFO pbtdi, ref Guid pGuidService, uint dwServiceFlags);

public static void SearchBluetoothDevices()
{
    BLUETOOTH_FIND_DEVICE_SEARCH_PARAMS searchParams = new BLUETOOTH_FIND_DEVICE_SEARCH_PARAMS();
    searchParams.fReturnAuthenticated = true;
    searchParams.fReturnRemembered = true;
    searchParams.fReturnUnknown = true;
    searchParams.fReturnConnected = true;
    searchParams.fIssueInquiry = true;
    searchParams.cTimeoutMultiplier = 4;
    searchParams.hRadio = IntPtr.Zero;

    BLUETOOTH_DEVICE_INFO deviceInfo = new BLUETOOTH_DEVICE_INFO();
    deviceInfo.dwSize = Marshal.SizeOf(deviceInfo);

    IntPtr hFind = BluetoothFindFirstDevice(ref searchParams, ref deviceInfo);

    while (hFind.ToInt64() != -1)
    {
        Debug.WriteLine(deviceInfo.szName);

        BluetoothFindNextDevice(hFind, ref deviceInfo);
    }
    BluetoothFindDeviceClose(hFind.ToInt64());
}

三、实现数据传输
当我们找到了需要连接的蓝牙设备之后，接下来便是实现数据的传输。蓝牙数据传输的方式一般有两种，采用RFCOMM协议或采用SPP协议。这里我们以RFCOMM协议为例，提供以下两个示例代码。

1. 基本数据传输
   在RFCOMM协议下，我们需要使用BluetoothSerialPort类来进行数据的发送和接收。这里提供一个基本的代码示例。

using System.IO.Ports;
using Windows.Devices.Bluetooth.Rfcomm;
using Windows.Devices.Enumeration;

//...

//创建蓝牙socket并连接蓝牙设备
private async Task<bool> ConnectAsync(string deviceId, Guid serviceUuid)
{
    var startupTask = StartupTask.GetAsync("MyStartupTaskId");

    RfcommDeviceService rfcommService;
    try
    {
        //建立设备
        DeviceInformation allPairedDevices =
            await DeviceInformation.CreateFromIdAsync(deviceId);

        rfcommService =
            await RfcommDeviceService.FromIdAsync(allPairedDevices.Id);

        if (rfcommService == null)
        {
            Debug.WriteLine("此设备无法进行无线通讯。");
            return false;
        }

        //创建蓝牙socket并连接蓝牙设备
        socket = new StreamSocket();
        await socket.ConnectAsync(
            rfcommService.ConnectionHostName,
            rfcommService.ConnectionServiceName,
            SocketProtectionLevel.BluetoothEncryptionAllowNullAuthentication);

        DataReader reader = new DataReader(socket.InputStream);
        DataWriter writer = new DataWriter(socket.OutputStream);

        while (true)
        {
            //发送数据
            writer.WriteBytes(new byte[] { 0x30, 0x31, 0x32, 0x33, 0x34 });
            await writer.StoreAsync();

            //读取响应数据
            await reader.LoadAsync(1024);
            byte[] responseBytes = new byte[reader.UnconsumedBufferLength];
            reader.ReadBytes(responseBytes);
            Debug.WriteLine($"响应：{Encoding.UTF8.GetString(responseBytes)}");

            await Task.Delay(1000);
        }
    }
    catch (Exception e)
    {
        Debug.WriteLine($"发生异常：{e.Message}");
        return false;
    }
}

1. 创建虚拟串口
   我们可以使用第三方类库“32feet.NET”来创建虚拟串口。首先我们需要通过该类库创建一个蓝牙客户端，通过客户端的Stream属性进行数据的读写操作。代码示例如下：

string selectDeviceName = "<Your Device Name>";
string serviceString = BluetoothService.SerialPort.ToString();
BluetoothAddress selectDeviceAddress = BluetoothAddress.None;
BluetoothClient bluetoothClient = new BluetoothClient();
BluetoothDeviceInfo selectDevice = null;
Stream btStream = null;

//查找并连接蓝牙设备
BluetoothDeviceInfo[] devices = bluetoothClient.DiscoverDevices();
foreach (BluetoothDeviceInfo device in devices)
{
    if (device.DeviceName.Equals(selectDeviceName))
    {
        selectDevice = device;
        break;
    }
}
if (selectDevice == null)
{
    //未找到目标蓝牙
}
else
{
    //创建RFCOMM蓝牙服务
    BluetoothClient bc = new BluetoothClient();
    bc.Connect(selectDevice.DeviceAddress, new Guid("{00001101-0000-1000-8000-00805F9B34FB}"));

    //打开串口
    btStream = bc.GetStream();
    if (btStream == null)
    {
        //无法打开串口
    }

    //开始读取数据
    bool startExecuted = false;
    byte[] buffer = new byte[4096];
    while (true)
    {
        if (btStream != null && btStream.CanRead)
        {
            int bytesRead = btStream.Read(buffer,0,buffer.Length);

            //...
        }

        Thread.Sleep(100)
    }
}

以上就是使用C#语言在PC上实现蓝牙设备的搜索与数据传输的详细攻略。本文提供了两种蓝牙设备的搜索方式和两种RFCOMM协议下的数据传输方式。我们可以根据实际的需求进行选择和优化。