近期项目中用到蓝牙BLE，需要区分设备及显示蓝牙名。对于蓝牙BLE广播，发送字节数超过31会广播失败（原因之一是蓝牙名称太长），再者蓝牙mac地址是动态的无法区分设备。和同事交流后，采用他的项目中的方法。
名称太长问题
- 广播时，不添加Service UUID，采用2个字节表示服务。
- 蓝牙名字符长度超过10则截取前十个字符，并发送表示名称不完整的字节。
设备唯一性
随机两个数字保存在本地，广播时作为设备码（占用2个字节）发送。
代码实现
广播数据部分
private AdvertiseData buildAdvertiseData(boolean includeDeviceName) {
SharedPreferences sharedPreferences = mContext.getSharedPreferences("config_ble", Context.MODE_PRIVATE);
int key1 = sharedPreferences.getInt("key1", 0);
int key2 = sharedPreferences.getInt("key2", 0);
if (key1 == 0 || key2 == 0) {
Random random = new Random();
key1 = 10 + random.nextInt(89);
key2 = 10 + random.nextInt(89);
sharedPreferences.edit().putInt("key1", key1).putInt("key2", key2).apply();
}
String name = mBluetoothAdapter.getName();
boolean isFullName = true;
int maxNameLength = 10;
if (TextUtils.isEmpty(name)) {
name = String.format("BLE-%s%s", key1, key2);
} else {
if (name.length() > maxNameLength) {
name = name.substring(0, maxNameLength);
isFullName = false;
}
}
byte[] bytes = name.getBytes(StandardCharsets.UTF_8);
byte[] nameBytes = new byte[bytes.length + 1];
nameBytes[0] = (byte) (isFullName ? 1 : 0);
System.arraycopy(bytes, 0, nameBytes, 1, bytes.length);
String realName = isFullName ? name : (name + "...");
return
new AdvertiseData.Builder()
.setIncludeDeviceName(false) //包含蓝牙名称，不能传送名字(太长超过31字节)，会广播不成功
.addManufacturerData(0, new byte[]{0x6A, 0x7E}) //标识该服务
.addManufacturerData(1, new byte[]{(byte) key1, (byte) key2})//设备码
.addManufacturerData(2, nameBytes)//蓝牙名
.build();
}
蓝牙扫描过滤
private fun buildScanFilter(): List<ScanFilter> {
val scanFilters = ArrayList<ScanFilter>()
val filter = ScanFilter.Builder()
.setManufacturerData(0, new byte[]{0x6A, 0x7E})
.build()
scanFilters.add(filter)
return scanFilters
}
蓝牙数据ScanResult解析
val scanRecord = scanResult?.scanRecord
val deviceCode: Int =
scanRecord?.getManufacturerSpecificData(1)?.let { 100 * it[0] + it[1] } ?: 0
val deviceName = scanRecord?.getManufacturerSpecificData(2)?.let { bytes ->
val name = String(bytes.sliceArray(1 until bytes.size))
if (bytes[0].toInt() == 0) {
"$name..."
} else {
name
}
} ?: "null"