在Android中读取广告包 [英] Read advertisement packet in Android
问题描述
我正在研究用于宣传制造商特定数据的BLE传感器.是否有任何示例代码演示如何在Android中接收广告包并解析其有效载荷?
I'm working on a BLE sensor that is advertising manufacturer specific data. Is there any sample code that demonstrates how to receive an advertisement packet in Android and parse its payload?
推荐答案
这就是我想要的:
BLE扫描API BluetoothAdapter.startLeScan(ScanCallback)需要回调函数来获取扫描结果.该方法需要如下所示:
The BLE scan API BluetoothAdapter.startLeScan(ScanCallback) requires a call back function for the scan results. the method needs to look like the following:
private BluetoothAdapter.LeScanCallback ScanCallback =
new BluetoothAdapter.LeScanCallback()onLeScan(final BluetoothDevice device,
int rssi,
final byte[] scanRecord)
{...}
scanRecord变量是一个字节数组，其中包含Advertisement数据包有效负载.
And the scanRecord variable is a byte array which contains the Advertisement packet payload.
根据BLE规范，有效负载的结构非常简单，如下所示:
Per the BLE specification the structure of the payload is very simple as follows:
数据包的最大长度为47个字节，包括:
The packets can be up to 47 bytes in length and consist of:
- 1个字节的前同步码
- 4字节访问地址
- 2-39个字节的广告频道PDU
- 3个字节的CRC
对于广告通信渠道，访问地址始终为0x8E89BED6.
For advertisement communication channels, the access address is always 0x8E89BED6.
PDU依次具有其自己的标头(2个字节:有效载荷的大小及其类型–设备是否支持连接等)和实际的有效载荷(最多37个字节).
The PDU in turn has its own header (2 bytes: size of the payload and its type – whether the device supports connections, etc.) and the actual payload (up to 37 bytes).
最后，有效载荷的前6个字节是设备的MAC地址，实际信息最多可以包含31个字节.
Finally, the first 6 bytes of the payload are the MAC address of the device, and the actual information can have up to 31 bytes.
实际信息的格式如下:
第一个字节是数据的长度，第二个字节是类型，后跟数据.
first byte is length of the data and second byte is type followed by the data.
这是一种聪明的方法，允许任何应用程序在不关心内容的情况下跳过整个数据记录.
This is a clever way to allow any application to skip entire data records if they don't care about the contents.
以下是确定广告包内容的示例代码:
Here is the sample code to determine the contents of the Advertisement packet:
parseAdvertisementPacket(final byte[] scanRecord) {
byte[] advertisedData = Arrays.copyOf(scanRecord, scanRecord.length);
int offset = 0;
while (offset < (advertisedData.length - 2)) {
int len = advertisedData[offset++];
if (len == 0)
break;
int type = advertisedData[offset++];
switch (type) {
case 0x02: // Partial list of 16-bit UUIDs
case 0x03: // Complete list of 16-bit UUIDs
while (len > 1) {
int uuid16 = advertisedData[offset++] & 0xFF;
uuid16 |= (advertisedData[offset++] << 8);
len -= 2;
uuids.add(UUID.fromString(String.format(
"%08x-0000-1000-8000-00805f9b34fb", uuid16)));
}
break;
case 0x06:// Partial list of 128-bit UUIDs
case 0x07:// Complete list of 128-bit UUIDs
// Loop through the advertised 128-bit UUID's.
while (len >= 16) {
try {
// Wrap the advertised bits and order them.
ByteBuffer buffer = ByteBuffer.wrap(advertisedData,
offset++, 16).order(ByteOrder.LITTLE_ENDIAN);
long mostSignificantBit = buffer.getLong();
long leastSignificantBit = buffer.getLong();
uuids.add(new UUID(leastSignificantBit,
mostSignificantBit));
} catch (IndexOutOfBoundsException e) {
// Defensive programming.
Log.e("BlueToothDeviceFilter.parseUUID", e.toString());
continue;
} finally {
// Move the offset to read the next uuid.
offset += 15;
len -= 16;
}
}
break;
case 0xFF: // Manufacturer Specific Data
Log.d(TAG, "Manufacturer Specific Data size:" + len +" bytes" );
while (len > 1) {
if(i < 32) {
MfgData[i++] = advertisedData[offset++];
}
len -= 1;
}
Log.d(TAG, "Manufacturer Specific Data saved." + MfgData.toString());
break;
default:
offset += (len - 1);
break;
}
}
感谢
质量使我朝着正确的方向前进！
mass for putting me on the right direction!
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