. entry/src
|-- common // 常量以及工具库
|   |-- CommonConstants.ets 
|   |-- Logger.ets          
|   `-- PermissionUtil.ets
|-- entryability
|   `-- EntryAbility.ets
|-- pages 
|   |-- Index.ets // 主页
`-- servers
    |-- BLEScanManager.ets // BLE 设备扫描实现
    	// 开启扫描
    	public startScan() 
   		// 关闭扫描
        public stopScan()  
    	// 回调的形式返回扫描结果
        public onScanResultCallback(data: Callback<ble.ScanResult>)
    |-- BLEGattClientManager.ets// BLE 特征值管理实现
    	//写入server端服务的特征值时调用 
        public writeCharacteristicValue(Value:string)   
    	// client端主动连接时调用
        public startConnect(peerDevice: string)   
    	// 订阅指定的BLE服务特征数据
        public GetMsg(callback: Callback<string>)
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@Entry
@Component
struct Index {
  build() {
    Column({space:20}) {
      Text(this.message)
        .id('Ble Test')
        .fontSize(20)
        .fontWeight(FontWeight.Bold)

      // APP客户端连接BLE服务端实现子组件
      BleScan({deviceId:this.deviceId,deviceName:this.deviceName})

    }.justifyContent(FlexAlign.Center)
    .height('100%')
    .width('100%')
  }
}
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// APP客户端连接BLE服务端实现子组件
@Component
struct BleScan {
  build() {
    Column({space:10}){
      // 扫描到的设备列表
      List({ space: 10 }) {
        ForEach(this.bleDevicesArray, (data: ble.ScanResult, index: number) => {
          ListItem() {
             ....
              }.justifyContent(FlexAlign.Start).width('100%')
              .onClick(() => { // 点击对应设备，高亮并获取设备ID与设备名，用于后续连接
                this.deviceId = data.deviceId;
                this.deviceName = data.deviceName;
                this.clickNum = index;
              })
              Divider()
            }
          } // 被选择的BLE设备高亮显示。
          .backgroundColor(this.clickNum==index?'#32C5FF':Color.Transparent)
        })
      }
      .onReachEnd(()=>{ // 滑动到列表底部后刷新扫描列表
        bleScanManager.onScanResultCallback(this.BleScanCallback);
      })
      // 收到、发送的数据编辑区
      Row()
      {
         ... // 展示收到的数据
      }
      // 连接、断开、订阅、发送按钮
      Row({space:25})
      {
          ... // 实现功能按钮
      }
    }.height('70%')
  }
}
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 // Index.ets 页面渲染之前开启扫描并订阅扫描结果
aboutToAppear(): void {
    bleScanManager.onScanResultCallback(this.BleScanCallback);
    bleScanManager.startScan();
  }
// 订阅扫描回调
private BleScanCallback: Callback<ble.ScanResult> = (data: ble.ScanResult) => {
    if ((!this.bleDevicesArray.some(item => item.deviceId === data.deviceId)) && data.deviceName !== '') {
      this.bleDevicesArray.push(data)
    }
  };
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  // client端主动连接时调用
  public startConnect(peerDevice: string) { // 对端设备一般通过ble scan获取到
    ...
    console.info(TAG, 'startConnect ' + peerDevice);
    // 使用peerDevice构造gattClient，后续的交互都需要使用该实例
    this.gattClient = ble.createGattClientDevice(peerDevice);
    try {
      this.gattClient.connect(); // 2.3 发起连接
      this.onGattClientStateChange(); // 2.2 订阅连接状态
    } catch (err) {
			...
    }
  }
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myServiceUuid: string = '00009011-0000-1000-8000-00805F9B34FB';
myCharacteristicUuid: string = '00009012-0000-1000-8000-00805F9B34FB';
// 2902一般用于notification或者indication
myFirstDescriptorUuid: string = '00002902-0000-1000-8000-00805F9B34FB'; 
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// client端连接成功后，需要进行服务发现
public discoverServices() {
  ...
  try {
    this.gattClient.getServices().then((result: Array<ble.GattService>) => {
      console.info(TAG, 'getServices success: ' + JSON.stringify(result));
      // 要确保server端的服务内容有业务所需要的服务
      this.found = this.checkService(result);
    });
  } catch (err) {
      ...
  }
}
// 检测扫描到的服务
private checkService(services: Array<ble.GattService>): boolean {
  for (let i = 0; i < services.length; i++) { 
       // 对比服务UUID
    if (services[i].serviceUuid != this.myServiceUuid) {
      continue;
    }
    for (let j = 0; j < services[i].characteristics.length; j++) {
       // 对比特征UUID
      if (services[i].characteristics[j].characteristicUuid != this.myCharacteristicUuid) {
        continue;
      }
      for (let k = 0; k < services[i].characteristics[j].descriptors.length; k++) {
       // 对比特征描述UUID 2902
        if (services[i].characteristics[j].descriptors[k].descriptorUuid == this.myFirstDescriptorUuid) {
          console.info(TAG, 'find expected service from server');
          return true;
        }
      }
    }
  }
  console.error(TAG, 'no expected service from server');
  return false;
}
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  // 构造BLECharacteristic
  private initCharacteristic(): ble.BLECharacteristic {
    let descriptors: Array<ble.BLEDescriptor> = [];
    let descBuffer = new ArrayBuffer(2);
    let descValue = new Uint8Array(descBuffer);
    descValue[0] = 11;
    descValue[1] = 12;
    descriptors[0] = this.initDescriptor(this.myFirstDescriptorUuid, new ArrayBuffer(2));
    let charBuffer = new ArrayBuffer(2);
    let charValue = new Uint8Array(charBuffer);
    charValue[0] = 1;
    charValue[1] = 2;
    let characteristic: ble.BLECharacteristic = {
      serviceUuid: this.myServiceUuid,
      characteristicUuid: this.myCharacteristicUuid,
      characteristicValue: charBuffer,
      descriptors: descriptors
    };
    return characteristic;
  }
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 // 扫描、连接到对应的BLE server后，订阅指定的BLE服务特征数据
public GetMsg(callback: Callback<string>)
{
  try {
        this.gattClient.setCharacteristicChangeNotification(this.initCharacteristic(), true).then(() => {
              console.info(TAG, `get ble server notify success`);
              try {
   this.gattClient!.on('BLECharacteristicChange', (characteristicChangeReq: ble.BLECharacteristic) => {
    let value: Uint8Array = new Uint8Array(characteristicChangeReq.characteristicValue);
    let textDecoder = util.TextDecoder.create('utf-8');
     // 接收BLE Server消息,Uint8Array 转为string
    let retStr = textDecoder.decodeWithStream(value); 
      			...
                  callback(retStr);
                });
              } catch (err) {
                  ...
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   Button('发 送').onClick(()=>{
          // 1.要确保server端的服务内容有业务所需要的服务
          // 2.在确保拿到了server端的服务结果后，读取到了需要的server端特定服务的特征
          // 3.连接到对应的BLE server后，对指定的BLE服务特征进行写入
          if(this.BleConnectState==constant.ProfileConnectionState.STATE_CONNECTED)
          {
            gattClientManager.writeCharacteristicValue(this.writeCharacteristicValue)
          }
        })
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  // 5. 在确保拿到了server端的服务结果后，写入server端特定服务的特征值时调用
  public writeCharacteristicValue(Value:string) {
      ...
    if (!this.found) { // 要确保server端有对应的characteristic
      console.error(TAG, 'no characteristic from server');
      return;
    }
    // 构造服务和特征
     ...
    // 转换需要写入的数据
    let charBuffer = new ArrayBuffer(Value.length);
    let charValue = new Uint8Array(charBuffer);
    for(let i=0; i<Value.length;i++)
    {
      charValue[i] = Value.charCodeAt(i);  // 字符转换为unicode
    }
    let characteristic: ble.BLECharacteristic = {
      serviceUuid: this.myServiceUuid,
      characteristicUuid: this.myCharacteristicUuid,
      characteristicValue: charBuffer,
      descriptors: descriptors
    };
    console.info(TAG, 'writeCharacteristicValue');
    try { // WRITE_NO_RESPONSE方式写入BLE设备的特征
      this.gattClient.writeCharacteristicValue(characteristic, ble.GattWriteType.WRITE_NO_RESPONSE, (err) => {
       ...
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