我正在尝试实现 Xamarin 中的 BLE 表单 .我要发送数据大于 20 个字节。我已经看到使用 java 在 native android 中的实现。它看起来像下面
private void sendMessage(BluetoothGattCharacteristic characteristic, String CHARACTERS){
byte[] initial_packet = new byte[3];
/**
* Indicate byte
*/
initial_packet[0] = BLE.INITIAL_MESSAGE_PACKET;
if (Long.valueOf(
String.valueOf(CHARACTERS.length() + initial_packet.length))
> BLE.DEFAULT_BYTES_VIA_BLE) {
sendingContinuePacket(characteristic, initial_packet, CHARACTERS);
} else {
sendingLastPacket(characteristic, initial_packet, CHARACTERS);
}
}
private void sendingContinuePacket(BluetoothGattCharacteristic characteristic,
byte[] initial_packet, String CHARACTERS){
/**
* TODO If data length > Default data can sent via BLE : 20 bytes
*/
// Check the data length is large how many times with Default Data (BLE)
int times = Byte.valueOf(String.valueOf(
CHARACTERS.length() / BLE.DEFAULT_BYTES_IN_CONTINUE_PACKET));
Log.i(TAG, "CHARACTERS.length() " + CHARACTERS.length());
Log.i(TAG, "times " + times);
// TODO
// 100 : Success
// 101 : Error
byte[] sending_continue_hex = new byte[BLE.DEFAULT_BYTES_IN_CONTINUE_PACKET];
for (int time = 0; time <= times; time++) {
/**
* Wait second before sending continue packet
*/
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
if (time == times) {
Log.i(TAG, "LAST PACKET ");
/**
* If you do not have enough characters to send continue packet,
* This is the last packet that will be sent to the band
*/
/**
* Packet length byte :
*/
/**
* Length of last packet
*/
int character_length = CHARACTERS.length()
- BLE.DEFAULT_BYTES_IN_CONTINUE_PACKET*times;
initial_packet[1] = Byte.valueOf(String.valueOf(character_length
+ BLE.INITIAL_MESSAGE_PACKET_LENGTH));
initial_packet[2] = BLE.SENDING_LAST_PACKET;
Log.i(TAG, "character_length " + character_length);
/**
* Message
*/
// Hex file
byte[] sending_last_hex = new byte[character_length];
// Hex file : Get next bytes
for (int i = 0; i < sending_last_hex.length; i++) {
sending_last_hex[i] =
CHARACTERS.getBytes()[sending_continue_hex.length*time + i];
}
// Merge byte[]
byte[] last_packet =
new byte[character_length + BLE.INITIAL_MESSAGE_PACKET_LENGTH];
System.arraycopy(initial_packet, 0, last_packet,
0, initial_packet.length);
System.arraycopy(sending_last_hex, 0, last_packet,
initial_packet.length, sending_last_hex.length);
// Set value for characteristic
characteristic.setValue(last_packet);
} else {
Log.i(TAG, "CONTINUE PACKET ");
/**
* If you have enough characters to send continue packet,
* This is the continue packet that will be sent to the band
*/
/**
* Packet length byte
*/
int character_length = sending_continue_hex.length;
/**
* TODO Default Length : 20 Bytes
*/
initial_packet[1] = Byte.valueOf(String.valueOf(
character_length + BLE.INITIAL_MESSAGE_PACKET_LENGTH));
/**
* If sent data length > 20 bytes (Default : BLE allow send 20 bytes one time)
* -> set 01 : continue sending next packet
* else or if after sent until data length < 20 bytes
* -> set 00 : last packet
*/
initial_packet[2] = BLE.SENDING_CONTINUE_PACKET;
/**
* Message
*/
// Hex file : Get first 17 bytes
for (int i = 0; i < sending_continue_hex.length; i++) {
Log.i(TAG, "Send stt : "
+ (sending_continue_hex.length*time + i));
// Get next bytes
sending_continue_hex[i] =
CHARACTERS.getBytes()[sending_continue_hex.length*time + i];
}
// Merge byte[]
byte[] sending_continue_packet =
new byte[character_length + BLE.INITIAL_MESSAGE_PACKET_LENGTH];
System.arraycopy(initial_packet, 0, sending_continue_packet,
0, initial_packet.length);
System.arraycopy(sending_continue_hex, 0, sending_continue_packet,
initial_packet.length, sending_continue_hex.length);
// Set value for characteristic
characteristic.setValue(sending_continue_packet);
}
// Write characteristic via BLE
mBluetoothGatt.writeCharacteristic(characteristic);
}
}
public boolean writeCharacteristic(BluetoothGattCharacteristic characteristic,
String data) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return false;
}
if (ActivityBLEController.IS_FIRST_TIME) {
/**
* In the first time,
* should send the Title
*/
byte[] merge_title = sendTitle(data);
// Set value for characteristic
characteristic.setValue(merge_title);
// Write characteristic via BLE
mBluetoothGatt.writeCharacteristic(characteristic);
// Reset
ActivityBLEController.IS_FIRST_TIME = false;
return true;
} else {
/**
* In the second time,
* should send the Message
*/
if (data.length() <= BLE.LIMIT_CHARACTERS) {
sendMessage(characteristic, data);
// Reset
ActivityBLEController.IS_FIRST_TIME = true;
return true;
} else {
// Typed character
typed_character = data.length();
return false;
}
}
}
private async Task<string> ReadAndWriteCharacterisicsValue(ICharacteristic _characteristics)
{
if (_characteristics != null)
{
var sbnew = new StringBuilder("BLE Characteristics\n");
byte[] senddata = Encoding.UTF8.GetBytes(string.IsNullOrEmpty("") ? "Hi1290004847846767627723676" : "");
if (MainThread.IsMainThread)
{
string writeTypes = _characteristics.WriteType.ToString();
await _characteristics.WriteAsync(senddata);
}
//_characteristics.ReadAsync();
var charVal = _characteristics.Value;
var str = Encoding.UTF8.GetString(charVal);
sbnew.AppendLine($"Characteristics found on this device: {string.Join(", ", str.ToString())}");
return sbnew.ToString();
}
return null;
}
if (_characteristics != null)
{
try
{
var sbnew = new StringBuilder("BLE Characteristics\n");
byte[] senddata = Encoding.UTF8.GetBytes(string.IsNullOrEmpty("") ? "Start{'command':'UnSelectEnhancement','data':[{'UnSelectEnhancement':'VitaminC'},{'UnSelectEnhancement':'CitricAcid'}, {'UnSelectEnhancement':'Electolytes'},{'UnSelectEnhancement':'Sweetener'}]}End":"");
await _device.RequestMtuAsync(2000);
if (MainThread.IsMainThread)
{
string writeTypes = _characteristics.WriteType.ToString();
await _characteristics.WriteAsync(senddata);
}
IEnumerable<string> s = str.Split();
IEnumerable<string> Split( )
{
while (!string.IsNullOrWhiteSpace(str))
{
var chunk = str.Take(size).ToArray();
str = str.Substring(chunk.Length);
yield return new string(chunk);
}
}
Console.WriteLine("Error of split");
Console.WriteLine(String.Join(Environment.NewLine, str));
Console.WriteLine(String.Join(Environment.NewLine, str));
最佳答案
您可以尝试以多个 block 的形式发送数据，每个 block 的最大大小为 20。
此示例发送第一个 20 字节 block ，然后发送另一个带有剩余 7 个字节的 block 。
byte[] senddata = Encoding.ASCII.GetBytes("Hi1290004847846767627723676");
int start = 0;
while (start < senddata.Length)
{
int chunkLength = Math.Min(20, senddata.Length - start);
byte[] chunk = new byte[chunkLength];
Array.Copy(senddata, start, chunk, 0, chunkLength);
await writeBuf.WriteAsync(chunk);
start += 20;
}
关于java - 如何在 Xamarin 表单中为 BLE 拆分和发送 >20 字节的数据？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/65246453/