Windows BLE 开发指南（Rust windows-rs）
本演示在 Windows 平台使用 Rust 的 windows-rs 库进行 BLE（低功耗蓝牙）开发：扫描设备、连接与服务发现、选择特征、启用通知（CCCD）、发送与接收数据、断开与清理，同时给出“已配对设备重启”场景的稳态策略
依赖与准备
在 Cargo.toml 添加依赖：
[dependencies]
windows = "0.56"
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
uuid = "1"
常用导入（放在你的模块或文件顶部）：
use windows::{
core::Result as WinResult,
Devices::Bluetooth::Advertisement::{
BluetoothLEAdvertisementWatcher, BluetoothLEAdvertisementReceivedEventArgs,
},
Devices::Bluetooth::{BluetoothLEDevice, BluetoothConnectionStatus},
Devices::Bluetooth::GenericAttributeProfile::{
GattDeviceService, GattCharacteristic, GattCharacteristicProperties,
GattClientCharacteristicConfigurationDescriptorValue, GattCommunicationStatus,
GattValueChangedEventArgs, GattProtectionLevel,
},
Devices::Enumeration::{
DeviceInformationCustomPairing, DevicePairingKinds, DevicePairingRequestedEventArgs,
DevicePairingResultStatus,
},
Foundation::TypedEventHandler,
Storage::Streams::DataReader,
};
辅助函数：UUID 字符串转 Windows GUID：
fn guid_from_str(s: &str) -> windows::core::GUID {
let u = uuid::Uuid::parse_str(s).expect("uuid parse error");
let (d1, d2, d3, d4) = u.as_fields();
windows::core::GUID::from_values(d1, d2, d3, *d4)
}
扫描与筛选设备
扫描 5 秒并返回设备列表（MAC 为 12 位十六进制字符串）：
#[derive(Debug, Clone)]
struct BleDevice { mac: String, name: String, rssi: Option<i16> }
async fn scan_devices(timeout_ms: u64) -> Vec<BleDevice> {
use std::{collections::HashMap, sync::Arc, time::Duration};
use tokio::sync::Mutex as AsyncMutex; // 广播事件是异步回调，这里用异步互斥保护聚合表
// address→设备信息 聚合表（Windows 提供 64 位地址，不是文本 MAC）
let map = Arc::new(AsyncMutex::new(HashMap::<u64, BleDevice>::new()));
let watcher = BluetoothLEAdvertisementWatcher::new().unwrap(); // 创建广播监听器
let map_cb = map.clone();
// 注册 Received 事件：每条广播提取地址/名称/RSSI 并写入聚合表
let _token = watcher.Received(&TypedEventHandler::new(
move |_sender: &Option<BluetoothLEAdvertisementWatcher>, args: &Option<BluetoothLEAdvertisementReceivedEventArgs>| -> WinResult<()> {
if let Some(args) = args.as_ref() {
let addr = args.BluetoothAddress()?; // 64 位地址（数值）
let mac = format!( // 转为 12 位十六进制字符串，便于统一筛选
"{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}",
(addr >> 40) & 0xff, (addr >> 32) & 0xff, (addr >> 24) & 0xff,
(addr >> 16) & 0xff, (addr >> 8) & 0xff, addr & 0xff
);
let name = args.Advertisement()?.LocalName()?.to_string(); // 本地名（可能空）
let rssi = args.RawSignalStrengthInDBm()?; // 信号强度（dBm）
if let Ok(mut m) = map_cb.try_lock() { // 非阻塞写入，避免回调卡住
m.entry(addr).and_modify(|d| { if d.name.is_empty() && !name.is_empty() { d.name = name.clone(); } d.rssi = Some(rssi); })
.or_insert(BleDevice { mac, name, rssi: Some(rssi) });
}
}
Ok(())
}
)).unwrap();
watcher.Start().unwrap(); // 开始监听广播
tokio::time::sleep(Duration::from_millis(timeout_ms)).await;
watcher.Stop().unwrap(); // 停止监听
let locked = map.lock().await; // 收敛为列表
let mut list: Vec<_> = locked.values().cloned().filter(|d| !d.name.is_empty()).collect();
list.sort_by_key(|d| d.mac.clone());
list
}
async fn filter_device(mac: &str, list: Vec<BleDevice>) -> Option<BleDevice> {
// 支持 "AA:BB:..." 或无分隔符/大小写不一致的输入
let mut s = mac.replace(":", "").replace('-', "").to_lowercase();
if s.len() != 12 || s.chars().any(|c| !c.is_ascii_hexdigit()) {
if let Ok(addr_hex) = u64::from_str_radix(&s, 16) { s = format!("{:012x}", addr_hex); }
else if let Ok(addr_dec) = s.parse::<u64>() { s = format!("{:012x}", addr_dec); }
}
list.into_iter().find(|d| d.mac == s)
}
为什么这么做：
- Windows 广播提供的是数值地址，统一转为 12 位十六进制更利于设备筛选与日志定位。
- 事件回调中尽量使用
try_lock，避免广播高频导致锁争用。
常见坑：
- 某些设备广播不带本地名，需允许空名称并在后续才筛掉。
- 扫描过短可能错过目标设备；根据场景调整
timeout_ms。
连接与服务发现
async fn connect_and_list_services(device: &BleDevice) -> BluetoothLEDevice {
let addr = u64::from_str_radix(&device.mac.replace(":", "").to_lowercase(), 16).unwrap(); // 文本 MAC → 数值地址
let dev = BluetoothLEDevice::FromBluetoothAddressAsync(addr).unwrap().await.unwrap(); // WinRT 异步获取设备对象
// 等待连接就绪：避免紧接着读服务/写 CCCD 命中未连接状态
for _ in 0..10 {
if dev.ConnectionStatus().unwrap() == BluetoothConnectionStatus::Connected { break; }
tokio::time::sleep(std::time::Duration::from_millis(200)).await;
}
// 列出服务（可选）：用于确认目标服务是否存在与刷新完成
let services = dev.GetGattServicesAsync().unwrap().await.unwrap();
if services.Status().unwrap() == GattCommunicationStatus::Success {
let list = services.Services().unwrap();
for s in list.into_iter() { println!("service uuid {:?}", s.Uuid().unwrap()); }
}
dev
}
- 某些设备在建立物理连接后，需要数百毫秒才进入
Connected；过早操作常导致不可达或读空服务。
常见坑：
- 忽略连接就绪轮询会触发后续“Unreachable”或启用通知中止（E_ABORT）。
特征选择（通知/写入）
按 GUID 过滤，否则枚举回退，并根据属性判定：
async fn select_notify(service: &GattDeviceService, guid: windows::core::GUID) -> Option<GattCharacteristic> {
let res = service.GetCharacteristicsForUuidAsync(guid).unwrap().await.unwrap();
if res.Status().unwrap() == GattCommunicationStatus::Success {
let list = res.Characteristics().unwrap();
for c in list.into_iter() {
let props = c.CharacteristicProperties().unwrap(); // 判定具备 Notify 或 Indicate
let ok = (props.0 & GattCharacteristicProperties::Notify.0) != 0 || (props.0 & GattCharacteristicProperties::Indicate.0) != 0;
if ok { return Some(c); }
}
}
// GUID 过滤失败时，枚举全部特征并匹配 GUID
let all = service.GetCharacteristicsAsync().unwrap().await.unwrap().Characteristics().unwrap();
for c in all.into_iter() { if c.Uuid().unwrap() == guid { return Some(c); } }
None
}
async fn select_write(service: &GattDeviceService, guid: windows::core::GUID) -> Option<GattCharacteristic> {
let res = service.GetCharacteristicsForUuidAsync(guid).unwrap().await.unwrap();
if res.Status().unwrap() == GattCommunicationStatus::Success {
let list = res.Characteristics().unwrap();
for c in list.into_iter() {
let p = c.CharacteristicProperties().unwrap(); // 判定具备 Write 或 WriteWithoutResponse
let ok = (p.0 & GattCharacteristicProperties::Write.0) != 0 || (p.0 & GattCharacteristicProperties::WriteWithoutResponse.0) != 0;
if ok { return Some(c); }
}
}
let all = service.GetCharacteristicsAsync().unwrap().await.unwrap().Characteristics().unwrap();
for c in all.into_iter() { if c.Uuid().unwrap() == guid { return Some(c); } }
None
}
- 设备端在刷新期间可能返回空列表，枚举回退能避免漏选；属性判定可避免误选不可用特征。
常见坑：
- 仅按 GUID 命中但属性不满足（无 Notify/Write），后续启用或写入会失败。
启用通知（CCCD）与回调注册
async fn enable_notify_with_retry(ch: &GattCharacteristic) -> bool {
tokio::time::sleep(std::time::Duration::from_millis(1000)).await; // 预延时，避开设备忙/栈刷新
for _ in 0..3 {
if let Ok(op) = ch.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue::Notify) {
if let Ok(status) = op.await { if status == GattCommunicationStatus::Success { return true; } } // 首选 Notify
}
tokio::time::sleep(std::time::Duration::from_millis(500)).await;
}
for _ in 0..2 {
if let Ok(op) = ch.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue::Indicate) {
if let Ok(status) = op.await { if status == GattCommunicationStatus::Success { return true; } } // 回退 Indicate
}
tokio::time::sleep(std::time::Duration::from_millis(500)).await;
}
false
}
fn register_value_changed(ch: &GattCharacteristic, mut on_notify: impl FnMut(Vec<u8>) + Send + 'static) {
let handler = TypedEventHandler::<GattCharacteristic, GattValueChangedEventArgs>::new(
move |_sender: &Option<GattCharacteristic>, args: &Option<GattValueChangedEventArgs>| {
if let Some(args) = args.as_ref() {
if let Ok(buf) = args.CharacteristicValue() {
if let Ok(reader) = DataReader::FromBuffer(&buf) { // IBuffer → Vec<u8>
if let Ok(len) = buf.Length() {
let mut data = vec![0u8; len as usize];
let _ = reader.ReadBytes(&mut data);
on_notify(data);
}
}
}
}
Ok(())
}
);
let _ = ch.ValueChanged(&handler);
}
- Notify 不需要 ACK，实时性好；设备只支持 Indicate 时需回退。
- IBuffer 转字节后交给上层解析，避免 WinRT 读取阻塞。
常见坑：
- 启用通知过早会被中止（E_ABORT）；加延时与重试能显著降低概率。
写入（带响应优先，失败回退无响应）
async fn write_with_result_and_fallback(ch: &GattCharacteristic, data: &[u8]) -> GattCommunicationStatus {
use windows::Storage::Streams::{InMemoryRandomAccessStream, DataWriter};
let stream = InMemoryRandomAccessStream::new().unwrap(); // 构造内存流
let out = stream.GetOutputStreamAt(0).unwrap(); // 取输出流
let writer = DataWriter::CreateDataWriter(&out).unwrap(); // 创建写入器
writer.WriteBytes(data).unwrap(); // 写入字节
let buf = writer.DetachBuffer().unwrap(); // 拆出 IBuffer
let res = ch.WriteValueWithResultAsync(&buf).unwrap().await.unwrap(); // 带响应写入
let status = res.Status().unwrap(); // 读取通信状态（可结合 ProtocolError 定位 ATT 错误）
if status != GattCommunicationStatus::Success {
let fb = ch.WriteValueAsync(&buf).unwrap().await.unwrap(); // 回退：无响应写入
return fb;
}
status
}
为什么这么做：
- 带响应写可获 ATT 错码（权限/长度/不允许等）；设备仅支持无响应写时自动回退。
常见坑：
- 未加密/未配对时常见
Insufficient Authentication；需先建立加密会话。
断开与清理（顺序至关重要）
async fn disconnect_cleanup(dev: &BluetoothLEDevice, notify_char: &GattCharacteristic, token: windows::Foundation::EventRegistrationToken) {
let _ = notify_char.RemoveValueChanged(token); // 先移除通知事件，避免回调残留
if let Ok(op) = notify_char.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue::None) { let _ = op.await; } // 关闭订阅（CCCD=None）
if let Ok(svc) = notify_char.Service() { if let Ok(sess) = svc.Session() { let _ = sess.SetMaintainConnection(false); } } // 取消保持连接
let _ = dev.Close(); // 关闭设备句柄
}
- 不正确的清理顺序会导致下次连接启用通知失败或会话不可达。
常见坑：
- 忘记
RemoveValueChanged 导致 ValueChanged 持有对象，写入 None 时报错。
已配对设备重启的稳态策略（清理 + 重试）
设备已在系统层“配对且连接”，当设备重启进入配对模式时，Windows 保留旧连接/GATT 缓存，常见错误：
- “notify characteristic not found”
- “enable notify/indicate failed” 或 E_ABORT（0x80004004）
建议在连接前执行 OS 级清理：
async fn unpair_and_close(address: u64) {
let dev = BluetoothLEDevice::FromBluetoothAddressAsync(address).unwrap().await.unwrap();
if let Ok(di) = dev.DeviceInformation() {
if let Ok(pairing) = di.Pairing() {
if pairing.IsPaired().unwrap_or(false) {
let _ = pairing.UnpairAsync().unwrap().await;
}
}
}
let _ = dev.Close();
tokio::time::sleep(std::time::Duration::from_millis(800)).await;
}
随后再进行连接、服务发现、特征选择与 CCCD 启用，并在各步骤加入适度延时与重试。
组合示例：连接→订阅→发送→接收→断开
#[tokio::main]
async fn main() {
let list = scan_devices(5000).await;
let dev = filter_device("208B37997529", list).expect("device not found");
let addr = u64::from_str_radix(&dev.mac, 16).unwrap();
unpair_and_close(addr).await; // 已配对场景建议先清理
let device = connect_and_list_services(&dev).await;
let service = {
let guid = guid_from_str("01000100-0000-1000-8000-009078563412");
let list = device.GetGattServicesAsync().unwrap().await.unwrap().Services().unwrap();
list.into_iter().find(|s| s.Uuid().unwrap() == guid).expect("service not found")
};
tokio::time::sleep(std::time::Duration::from_millis(800)).await;
let notify = select_notify(&service, guid_from_str("02000200-0000-1000-8000-009178563412")).expect("notify not found");
let writec = select_write(&service, guid_from_str("03000300-0000-1000-8000-009278563412")).expect("write not found");
let _ = notify.SetProtectionLevel(GattProtectionLevel::EncryptionRequired);
let _ = writec.SetProtectionLevel(GattProtectionLevel::EncryptionRequired);
if !enable_notify_with_retry(¬ify).await { panic!("enable notify failed"); }
register_value_changed(¬ify, |data| { println!("notify: {} bytes", data.len()); });
let payload = b"example payload";
let status = write_with_result_and_fallback(&writec, payload).await;
println!("write status: {:?}", status);
// 清理
// 注意：真实项目中保存 ValueChanged 注册的 token，并在断开时传入
let dummy_token = windows::Foundation::EventRegistrationToken { value: 0 };
disconnect_cleanup(&device, ¬ify, dummy_token).await;
}
故障排查与最佳实践
- WinRT await 与并发：将涉及 WinRT await 的代码放到阻塞线程或在当前线程执行，避免
Send 约束问题
- 连接就绪：轮询
BluetoothConnectionStatus::Connected 再进行特征与 CCCD 操作
- 特征与 CCCD：获取服务后延时、特征选择重试；CCCD 启用延时、Notify→Indicate 回退；必要时重新抓取一次特征再启用
- 已配对设备重启：务必先执行
UnpairAsync + Close + 延时 再连接，显著降低缓存不一致导致的失败
- 断开顺序：移除事件→CCCD=None→取消保持连接→Close 设备；不当的顺序会让下次连接启用通知失败
小结
本文给出了一套完整的、可直接复制的 Windows BLE 开发代码片段与操作步骤，涵盖扫描、连接与服务发现、特征选择、启用通知、写入与接收、断开清理，以及已配对设备重启场景的稳态策略。将这些片段按需组合，即可搭建稳定的 BLE 通信链路。
带详注的代码片段（逐行说明）
1) 扫描与筛选（详注版）
use windows::{
core::Result as WinResult,
Devices::Bluetooth::Advertisement::{
BluetoothLEAdvertisementWatcher, BluetoothLEAdvertisementReceivedEventArgs,
},
Foundation::TypedEventHandler,
};
use std::{collections::HashMap, sync::Arc, time::Duration};
use tokio::sync::Mutex as AsyncMutex;
#[derive(Debug, Clone)]
struct BleDevice { mac: String, name: String, rssi: Option<i16> }
// 扫描指定时长，聚合设备到列表
async fn scan_devices(timeout_ms: u64) -> Vec<BleDevice> {
// 使用共享 HashMap 聚合：Windows 广播给出的是 64 位地址（非文本 MAC）
let map = Arc::new(AsyncMutex::new(HashMap::<u64, BleDevice>::new()));
// 创建广播监听器
let watcher = BluetoothLEAdvertisementWatcher::new().unwrap();
let map_cb = map.clone();
// 注册接收事件：每条广播中提取地址、设备名与 RSSI
let _token = watcher.Received(&TypedEventHandler::new(
move |_sender: &Option<BluetoothLEAdvertisementWatcher>, args: &Option<BluetoothLEAdvertisementReceivedEventArgs>| -> WinResult<()> {
if let Some(args) = args.as_ref() {
// 设备地址为 64 位整型，转为 12 位十六进制字符串（不含分隔符）
let addr = args.BluetoothAddress()?;
let mac = format!(
"{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}",
(addr >> 40) & 0xff, (addr >> 32) & 0xff, (addr >> 24) & 0xff,
(addr >> 16) & 0xff, (addr >> 8) & 0xff, addr & 0xff
);
// 广告包中的本地名
let name = args.Advertisement()?.LocalName()?.to_string();
// 信号强度（可能不存在）
let rssi = args.RawSignalStrengthInDBm()?;
// 聚合到共享表：若已有记录则更新更有价值的信息（非空名称、最新 RSSI）
if let Ok(mut m) = map_cb.try_lock() {
m.entry(addr)
.and_modify(|d| { if d.name.is_empty() && !name.is_empty() { d.name = name.clone(); } d.rssi = Some(rssi); })
.or_insert(BleDevice { mac, name, rssi: Some(rssi) });
}
}
Ok(())
}
)).unwrap();
// 开始监听指定时间窗口
watcher.Start().unwrap();
tokio::time::sleep(Duration::from_millis(timeout_ms)).await;
watcher.Stop().unwrap();
// 收敛为列表并按 MAC 排序，过滤空名称
let locked = map.lock().await;
let mut list: Vec<_> = locked.values().cloned().filter(|d| !d.name.is_empty()).collect();
list.sort_by_key(|d| d.mac.clone());
list
}
// 按 MAC 文本筛选设备：支持去分隔符与大小写统一，兼容十六/十进制
async fn filter_device(mac: &str, list: Vec<BleDevice>) -> Option<BleDevice> {
let mut s = mac.replace(":", "").replace('-', "").to_lowercase();
if s.len() != 12 || s.chars().any(|c| !c.is_ascii_hexdigit()) {
if let Ok(addr_hex) = u64::from_str_radix(&s, 16) { s = format!("{:012x}", addr_hex); }
else if let Ok(addr_dec) = s.parse::<u64>() { s = format!("{:012x}", addr_dec); }
}
list.into_iter().find(|d| d.mac == s)
}
2) 连接与服务发现（详注版）
use windows::Devices::Bluetooth::{BluetoothLEDevice, BluetoothConnectionStatus};
use windows::Devices::Bluetooth::GenericAttributeProfile::{GattCommunicationStatus};
// 建立到设备的连接，并打印服务列表（用于诊断）
async fn connect_and_list_services(device: &BleDevice) -> BluetoothLEDevice {
// 文本 MAC → 64 位地址（十六进制解析）
let addr = u64::from_str_radix(&device.mac.replace(":", "").to_lowercase(), 16).unwrap();
// 异步获取设备对象（WinRT）
let dev = BluetoothLEDevice::FromBluetoothAddressAsync(addr).unwrap().await.unwrap();
// 连接就绪等待：部分设备需要一点时间进入 Connected 状态
for _ in 0..10 {
if dev.ConnectionStatus().unwrap() == BluetoothConnectionStatus::Connected { break; }
tokio::time::sleep(std::time::Duration::from_millis(200)).await;
}
// 枚举 GATT 服务并打印 UUID（便于确认服务是否刷新与存在）
let services = dev.GetGattServicesAsync().unwrap().await.unwrap();
if services.Status().unwrap() == GattCommunicationStatus::Success {
let list = services.Services().unwrap();
for s in list.into_iter() { println!("service uuid {:?}", s.Uuid().unwrap()); }
}
dev
}
3) 特征选择（详注版）
use windows::Devices::Bluetooth::GenericAttributeProfile::{
GattDeviceService, GattCharacteristic, GattCharacteristicProperties, GattCommunicationStatus,
};
// 选择通知特征：先 GUID 过滤 + 按属性检查；失败枚举全部回退
async fn select_notify(service: &GattDeviceService, guid: windows::core::GUID) -> Option<GattCharacteristic> {
let res = service.GetCharacteristicsForUuidAsync(guid).unwrap().await.unwrap();
if res.Status().unwrap() == GattCommunicationStatus::Success {
let list = res.Characteristics().unwrap();
for c in list.into_iter() {
let props = c.CharacteristicProperties().unwrap();
let ok = (props.0 & GattCharacteristicProperties::Notify.0) != 0 || (props.0 & GattCharacteristicProperties::Indicate.0) != 0;
if ok { return Some(c); }
}
}
// 枚举回退：某些设备在刷新期间 GUID 过滤可能返回空
let all = service.GetCharacteristicsAsync().unwrap().await.unwrap().Characteristics().unwrap();
for c in all.into_iter() { if c.Uuid().unwrap() == guid { return Some(c); } }
None
}
// 选择写特征：同理，需具备 Write 或 WriteWithoutResponse 属性
async fn select_write(service: &GattDeviceService, guid: windows::core::GUID) -> Option<GattCharacteristic> {
let res = service.GetCharacteristicsForUuidAsync(guid).unwrap().await.unwrap();
if res.Status().unwrap() == GattCommunicationStatus::Success {
let list = res.Characteristics().unwrap();
for c in list.into_iter() {
let p = c.CharacteristicProperties().unwrap();
let ok = (p.0 & GattCharacteristicProperties::Write.0) != 0 || (p.0 & GattCharacteristicProperties::WriteWithoutResponse.0) != 0;
if ok { return Some(c); }
}
}
let all = service.GetCharacteristicsAsync().unwrap().await.unwrap().Characteristics().unwrap();
for c in all.into_iter() { if c.Uuid().unwrap() == guid { return Some(c); } }
None
}
4) 启用通知与注册回调（详注版）
use windows::Devices::Bluetooth::GenericAttributeProfile::{
GattCharacteristic, GattClientCharacteristicConfigurationDescriptorValue, GattCommunicationStatus,
};
use windows::Devices::Bluetooth::GenericAttributeProfile::{GattValueChangedEventArgs};
use windows::Storage::Streams::DataReader;
use windows::Foundation::TypedEventHandler;
// 启用通知：优先 Notify，失败回退 Indicate；加入预延时与重试以跨过设备刷新窗口
async fn enable_notify_with_retry(ch: &GattCharacteristic) -> bool {
// 预延时：避免立即写 CCCD 命中设备忙或栈刷新
tokio::time::sleep(std::time::Duration::from_millis(1000)).await;
// 尝试 Notify 多次
for _ in 0..3 {
if let Ok(op) = ch.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue::Notify) {
if let Ok(status) = op.await { if status == GattCommunicationStatus::Success { return true; } }
}
tokio::time::sleep(std::time::Duration::from_millis(500)).await;
}
// 回退 Indicate
for _ in 0..2 {
if let Ok(op) = ch.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue::Indicate) {
if let Ok(status) = op.await { if status == GattCommunicationStatus::Success { return true; } }
}
tokio::time::sleep(std::time::Duration::from_millis(500)).await;
}
false
}
// 注册通知回调：将 IBuffer 转为 Vec<u8> 并交给调用者处理
fn register_value_changed(ch: &GattCharacteristic, mut on_notify: impl FnMut(Vec<u8>) + Send + 'static) {
let handler = TypedEventHandler::<GattCharacteristic, GattValueChangedEventArgs>::new(
move |_sender: &Option<GattCharacteristic>, args: &Option<GattValueChangedEventArgs>| {
if let Some(args) = args.as_ref() {
if let Ok(buf) = args.CharacteristicValue() {
if let Ok(reader) = DataReader::FromBuffer(&buf) {
if let Ok(len) = buf.Length() {
let mut data = vec![0u8; len as usize];
let _ = reader.ReadBytes(&mut data);
on_notify(data);
}
}
}
}
Ok(())
}
);
let _ = ch.ValueChanged(&handler);
}
5) 写入（详注版）
use windows::Devices::Bluetooth::GenericAttributeProfile::{GattCharacteristic, GattCommunicationStatus};
use windows::Storage::Streams::{InMemoryRandomAccessStream, DataWriter};
// 写入封装：优先带响应写入（便于获取协议错误），失败回退无响应
async fn write_with_result_and_fallback(ch: &GattCharacteristic, data: &[u8]) -> GattCommunicationStatus {
// WinRT 写入 API 需要 IBuffer；这里通过内存流 + DataWriter 构造缓冲区
let stream = InMemoryRandomAccessStream::new().unwrap();
let out = stream.GetOutputStreamAt(0).unwrap();
let writer = DataWriter::CreateDataWriter(&out).unwrap();
writer.WriteBytes(data).unwrap();
let buf = writer.DetachBuffer().unwrap();
// 带响应写入：可读取状态与协议错误码（ATT），便于定位权限或长度问题
let res = ch.WriteValueWithResultAsync(&buf).unwrap().await.unwrap();
let status = res.Status().unwrap();
if status != GattCommunicationStatus::Success {
// 回退为无响应写：部分设备仅允许无响应写
let fb = ch.WriteValueAsync(&buf).unwrap().await.unwrap();
return fb;
}
status
}
6) 断开与清理（详注版）
use windows::Devices::Bluetooth::BluetoothLEDevice;
use windows::Devices::Bluetooth::GenericAttributeProfile::{GattCharacteristic, GattClientCharacteristicConfigurationDescriptorValue};
// 断开顺序：RemoveValueChanged → CCCD=None → MaintainConnection(false) → Close
async fn disconnect_cleanup(dev: &BluetoothLEDevice, notify_char: &GattCharacteristic, token: windows::Foundation::EventRegistrationToken) {
let _ = notify_char.RemoveValueChanged(token);
if let Ok(op) = notify_char.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue::None) { let _ = op.await; }
if let Ok(svc) = notify_char.Service() { if let Ok(sess) = svc.Session() { let _ = sess.SetMaintainConnection(false); } }
let _ = dev.Close();
}
7) 已配对设备重启的清理（详注版）
use windows::Devices::Bluetooth::BluetoothLEDevice;
// 在已配对且系统持有旧连接的情况下：先 Unpair + Close 再连接，降低缓存不一致导致的失败
async fn unpair_and_close(address: u64) {
let dev = BluetoothLEDevice::FromBluetoothAddressAsync(address).unwrap().await.unwrap();
if let Ok(di) = dev.DeviceInformation() {
if let Ok(pairing) = di.Pairing() {
if pairing.IsPaired().unwrap_or(false) {
let _ = pairing.UnpairAsync().unwrap().await; // 解除配对，释放旧权限与密钥
}
}
}
let _ = dev.Close(); // 关闭旧设备句柄
tokio::time::sleep(std::time::Duration::from_millis(800)).await; // 等待栈刷新
}
8) 组合流程（详注版）
#[tokio::main]
async fn main() {
// 1) 扫描并选择目标设备
let list = scan_devices(5000).await;
let dev = filter_device("208B37997529", list).expect("device not found");
// 2) 已配对场景建议先清理旧状态（Unpair + Close + 延时）
let addr = u64::from_str_radix(&dev.mac, 16).unwrap();
unpair_and_close(addr).await;
// 3) 连接并输出服务列表（诊断用途）
let device = connect_and_list_services(&dev).await;
// 4) 获取目标服务（按 GUID 匹配）
let service = {
let guid = guid_from_str("01000100-0000-1000-8000-009078563412");
let list = device.GetGattServicesAsync().unwrap().await.unwrap().Services().unwrap();
list.into_iter().find(|s| s.Uuid().unwrap() == guid).expect("service not found")
};
// 5) 特征选择前短暂等待，随后选择通知与写特征
tokio::time::sleep(std::time::Duration::from_millis(800)).await;
let notify = select_notify(&service, guid_from_str("02000200-0000-1000-8000-009178563412")).expect("notify not found");
let writec = select_write(&service, guid_from_str("03000300-0000-1000-8000-009278563412")).expect("write not found");
// 6) 若设备要求加密，设置保护级别为加密
let _ = notify.SetProtectionLevel(windows::Devices::Bluetooth::GenericAttributeProfile::GattProtectionLevel::EncryptionRequired);
let _ = writec.SetProtectionLevel(windows::Devices::Bluetooth::GenericAttributeProfile::GattProtectionLevel::EncryptionRequired);
// 7) 启用通知（带重试/回退），并注册通知回调
if !enable_notify_with_retry(¬ify).await { panic!("enable notify failed"); }
register_value_changed(¬ify, |data| { println!("notify: {} bytes", data.len()); });
// 8) 写入示例负载（带响应优先，失败回退）
let payload = b"example payload";
let status = write_with_result_and_fallback(&writec, payload).await;
println!("write status: {:?}", status);
// 9) 断开与清理（真实项目中保存并传入 ValueChanged 的 token）
let dummy_token = windows::Foundation::EventRegistrationToken { value: 0 };
disconnect_cleanup(&device, ¬ify, dummy_token).await;
}
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