蓝牙低功耗广告

蓝牙低功耗 (BLE) 通过在大部分时间保持睡眠模式来节省电量。它仅在进行广告和短连接时唤醒，因此广告会影响功耗和数据传输带宽。

蓝牙 5 广告扩展

Android 8.0 支持蓝牙 5，它为 BLE 提供了广播改进和灵活的数据广告。蓝牙 5 支持蓝牙低功耗物理层 (PHY)，这些物理层保留了蓝牙 4.2 的低功耗特性，并允许用户选择更高的带宽或范围。如需了解详情，请参阅蓝牙 5 核心规范。

实现

运行 Android 8.0 且配备兼容蓝牙控制器的设备可自动使用新的蓝牙 5 功能。使用以下 BluetoothAdapter 方法来检查设备是否支持蓝牙 5 功能

  • isLe2MPhySupported()
  • isLeCodedPhySupported()
  • isLeExtendedAdvertisingSupported()
  • isLePeriodicAdvertisingSupported()

要停用广告功能，请与蓝牙芯片供应商合作以停用芯片组支持。

蓝牙 PHY 互斥，并且每个 PHY 的行为由蓝牙 SIG 预定义。默认情况下，Android 8.0 使用蓝牙 4.2 的蓝牙低功耗 1M PHY。android.bluetooth.le 软件包通过以下 API 公开蓝牙 5 广告功能

  • AdvertisingSet
  • AdvertisingSetCallback
  • AdvertisingSetParameters
  • PeriodicAdvertisingParameters

创建一个 AdvertisingSet，以使用 startAdvertisingSet() 方法在 android.bluetooth.le.BluetoothLeAdvertiser 中修改蓝牙广告设置。即使对蓝牙 5 或其广告功能的支持被禁用，API 功能也可能适用于低功耗 1M PHY。

示例

此示例应用使用蓝牙低功耗 1M PHY 进行广告

  // Start legacy advertising. Works for devices with 5.x controllers,
  // and devices that support multi-advertising.

  void example1() {
   BluetoothLeAdvertiser advertiser =
      BluetoothAdapter.getDefaultAdapter().getBluetoothLeAdvertiser();

   AdvertisingSetParameters parameters = (new AdvertisingSetParameters.Builder())
           .setLegacyMode(true) // True by default, but set here as a reminder.
           .setConnectable(true)
           .setInterval(AdvertisingSetParameters.INTERVAL_HIGH)
           .setTxPowerLevel(AdvertisingSetParameters.TX_POWER_MEDIUM)
           .build();

   AdvertiseData data = (new AdvertiseData.Builder()).setIncludeDeviceName(true).build();

   AdvertisingSetCallback callback = new AdvertisingSetCallback() {
       @Override
       public void onAdvertisingSetStarted(AdvertisingSet advertisingSet, int txPower, int status) {
           Log.i(LOG_TAG, "onAdvertisingSetStarted(): txPower:" + txPower + " , status: "
             + status);
           currentAdvertisingSet = advertisingSet;
       }

       @Override
       public void onAdvertisingDataSet(AdvertisingSet advertisingSet, int status) {
           Log.i(LOG_TAG, "onAdvertisingDataSet() :status:" + status);
       }

       @Override
       public void onScanResponseDataSet(AdvertisingSet advertisingSet, int status) {
           Log.i(LOG_TAG, "onScanResponseDataSet(): status:" + status);
       }

       @Override
       public void onAdvertisingSetStopped(AdvertisingSet advertisingSet) {
           Log.i(LOG_TAG, "onAdvertisingSetStopped():");
       }
   };

   advertiser.startAdvertisingSet(parameters, data, null, null, null, callback);

   // After onAdvertisingSetStarted callback is called, you can modify the
   // advertising data and scan response data:
   currentAdvertisingSet.setAdvertisingData(new AdvertiseData.Builder().
     setIncludeDeviceName(true).setIncludeTxPowerLevel(true).build());
   // Wait for onAdvertisingDataSet callback...
   currentAdvertisingSet.setScanResponseData(new
     AdvertiseData.Builder().addServiceUuid(new ParcelUuid(UUID.randomUUID())).build());
   // Wait for onScanResponseDataSet callback...

   // When done with the advertising:
   advertiser.stopAdvertisingSet(callback);
}

此示例应用使用 BLE 2M PHY 进行广告。该应用首先检查设备是否支持正在使用的功能。如果支持广告功能，则该应用会将 BLE 2M PHY 配置为主 PHY。当 2M PHY 处于活动状态时，广告不支持蓝牙 4.x 控制器，因此 setLegacyMode 设置为 false。此示例在广告时修改参数，并暂停广告。

void example2() {
   BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
   BluetoothLeAdvertiser advertiser =
     BluetoothAdapter.getDefaultAdapter().getBluetoothLeAdvertiser();

   // Check if all features are supported
   if (!adapter.isLe2MPhySupported()) {
       Log.e(LOG_TAG, "2M PHY not supported!");
       return;
   }
   if (!adapter.isLeExtendedAdvertisingSupported()) {
       Log.e(LOG_TAG, "LE Extended Advertising not supported!");
       return;
   }

   int maxDataLength = adapter.getLeMaximumAdvertisingDataLength();

   AdvertisingSetParameters.Builder parameters = (new AdvertisingSetParameters.Builder())
           .setLegacyMode(false)
           .setInterval(AdvertisingSetParameters.INTERVAL_HIGH)
           .setTxPowerLevel(AdvertisingSetParameters.TX_POWER_MEDIUM)
           .setPrimaryPhy(BluetoothDevice.PHY_LE_1M)
           .setSecondaryPhy(BluetoothDevice.PHY_LE_2M);

   AdvertiseData data = (new AdvertiseData.Builder()).addServiceData(new
     ParcelUuid(UUID.randomUUID()),
           "You should be able to fit large amounts of data up to maxDataLength. This goes
           up to 1650 bytes. For legacy advertising this would not
           work".getBytes()).build();

   AdvertisingSetCallback callback = new AdvertisingSetCallback() {
       @Override
       public void onAdvertisingSetStarted(AdvertisingSet advertisingSet, int txPower, int status) {
           Log.i(LOG_TAG, "onAdvertisingSetStarted(): txPower:" + txPower + " , status: "
            + status);
           currentAdvertisingSet = advertisingSet;
       }

       @Override
       public void onAdvertisingSetStopped(AdvertisingSet advertisingSet) {
           Log.i(LOG_TAG, "onAdvertisingSetStopped():");
       }
   };

   advertiser.startAdvertisingSet(parameters.build(), data, null, null, null, callback);

   // After the set starts, you can modify the data and parameters of currentAdvertisingSet.
   currentAdvertisingSet.setAdvertisingData((new
     AdvertiseData.Builder()).addServiceData(new ParcelUuid(UUID.randomUUID()),
           "Without disabling the advertiser first, you can set the data, if new data is
            less than 251 bytes long.".getBytes()).build());

   // Wait for onAdvertisingDataSet callback...

   // Can also stop and restart the advertising
   currentAdvertisingSet.enableAdvertising(false, 0, 0);
   // Wait for onAdvertisingEnabled callback...
   currentAdvertisingSet.enableAdvertising(true, 0, 0);
   // Wait for onAdvertisingEnabled callback...

   // Or modify the parameters - i.e. lower the tx power
   currentAdvertisingSet.enableAdvertising(false, 0, 0);
   // Wait for onAdvertisingEnabled callback...
   currentAdvertisingSet.setAdvertisingParameters(parameters.setTxPowerLevel
     (AdvertisingSetParameters.TX_POWER_LOW).build());
   // Wait for onAdvertisingParametersUpdated callback...
   currentAdvertisingSet.enableAdvertising(true, 0, 0);
   // Wait for onAdvertisingEnabled callback...

   // When done with the advertising:
   advertiser.stopAdvertisingSet(callback);
}

验证

运行适用的蓝牙产品测试，以验证设备与蓝牙 5 的兼容性。