树叶云鸿蒙OS教程：鸿蒙OS BLE扫描和广播

场景介绍

通过 BLE 扫描和广播提供的开放能力，可以根据指定状态获取外围设备、启动或停止 BLE 扫描、广播。

接口说明

中心设备进行 BLE 扫描

1. 进行 BLE 扫描之前先要继承 BleCentralManagerCallback 类实现 onScanCallback 和 onStartScanFailed 回调函数，用于接收扫描结果。

1. 调用BleCentralManager(BleCentralManagerCallback callback)接口获取中设备管理对象。

1. 获取扫描过滤器，过滤器为空时为不使用过滤器扫描，然后调用 startScan()开始扫描 BLE 设备，在回调中获取扫描到的 BLE 设备。

   // 实现扫描回调
   public class ScanCallback implements BleCentralManagerCallback{
       List<BleScanResult>results = new ArrayList<BleScanResult>();
       @Override
       public void onScanCallback(BleScanResult var1) {
           // 对扫描结果进行处理
           results.add(var1);
       }
       @Override    
       public void onStartScanFailed(int var1) {        
           HiLog.info(TAG,"Start Scan failed,Code:" + var1);    
       }
   }
   // 获取中心设备管理对象
   private ScanCallback centralManagerCallback = new ScanCallback();
   private BleCentralManager centralManager = new BleCentralManager(centralManagerCallback);
   // 创建扫描过滤器然后开始扫描
   List<BleScanFilter> filters = new ArrayList<BleScanFilter>();
   centralManager.startScan(filters);

外围设备进行 BLE 广播

1. 进行 BLE 广播前需要先继承 advertiseCallback 类实现 startResultEvent 回调，用于获取广播结果。

1. 调用接口 BleAdvertiser(Context context, BleAdvertiseCallback callback)获取广播对象，构造广播参数和广播数据。

1. 调用 startAdvertising(BleAdvertiseSettings settings, BleAdvertiseData advData, BleAdvertiseData scanResponse) 接口开始 BLE 广播。

   // 实现 BLE 广播回调
   private BleAdvertiseCallback advertiseCallback = new BleAdvertiseCallback() {
       @Override    
       public void startResultEvent(int result) {
           if(result == BleAdvertiseCallback.RESULT_SUCC){
               // 开始 BLE 广播成功
           }
           else {
               // 开始 BLE 广播失败
           }
       }
   };
   // 获取 BLE 广播对象
   private BleAdvertiser advertiser = new BleAdvertiser(this,advertiseCallback);
   // 创建 BLE 广播参数和数据
   private BleAdvertiseData data = new BleAdvertiseData.Builder()           
                           .addServiceUuid(SequenceUuid.uuidFromString(Server_UUID))      // 添加服务的 UUID                  
                           .addServiceData(SequenceUuid.uuidFromString(Server_UUID),new byte[]{0x11})    // 添加广播数据内容
                           .build();
   private BleAdvertiseSettings advertiseSettings = new BleAdvertiseSettings.Builder()                        
                          .setConnectable(true)                 // 设置是否可连接广播
                          .setInterval(BleAdvertiseSettings.INTERVAL_SLOT_DEFAULT)     // 设置广播间隔
                          .setTxPower(BleAdvertiseSettings.TX_POWER_DEFAULT)        // 设置广播功率
                          .build();
   // 开始广播
   advertiser.startAdvertising(advertiseSettings,data,null);