felHR85/USB 串行如何响应请求？

Question

我使用伽利略终端。终端通过RS-485将数据发送到android平板电脑。来自终端的数据到达平板电脑，但我不明白如何发送响应。他们使用 write 方法发送消息，但消息没有到达终端。这是我的代码：

package usb;

import android.app.PendingIntent;
import android.content.Intent;
import android.content.Context;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbDeviceConnection;
import android.hardware.usb.UsbManager;
import com.felhr.usbserial.UsbSerialDevice;
import com.felhr.usbserial.UsbSerialInterface;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.HashMap;
import android.widget.Toast;

public class UsbSerialManager {
    private UsbManager usbManager;
    private UsbSerialDevice serialPort;
    private PendingIntent permissionIntent;
    private Context context;
    private UsbDevice device;
    private boolean isTransmitting = false;
    private UsbReadCallback callbackFunction;

    public UsbSerialManager(Context context) {
        this.context = context;
        usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);
        setPermissionIntent();
    }

    private void setPermissionIntent() {
        Intent intent = new Intent("usb.USB_PERMISSION");
        permissionIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_MUTABLE);
    }

    public void requestPermission() {
        usbManager.requestPermission(device, permissionIntent);
    }

    public void getDevicesJson(Context context, UsbDevicesCallback callback) {
        HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList();

        if (deviceList.isEmpty()) {
            callback.onResult("");
            return;
        }
        JSONArray jsonArray = new JSONArray();

        try {
            for (UsbDevice device : deviceList.values()) {
                JSONObject jsonObject = new JSONObject();
                jsonObject.put("deviceName", device.getDeviceName());
                jsonObject.put("vendorId", device.getVendorId());
                jsonObject.put("productId", device.getProductId());
                jsonObject.put("version", device.getVersion());
                jsonObject.put("manufacturerName", device.getManufacturerName());
                jsonObject.put("productName", device.getProductName());
                jsonArray.put(jsonObject);
            }
            callback.onResult(jsonArray.toString());
        } catch (JSONException e) {
            e.printStackTrace();
            callback.onResult("");
        }
    }

    public void chooseDevice(int vendorId, int productId) {
        HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList();

        for (UsbDevice d : deviceList.values()) {
            if (d.getVendorId() == vendorId && d.getProductId() == productId) {
                device = d;
                break;
            }
        }
    }

    public void setupUsbConnection() {
        if (device != null) {
            UsbDeviceConnection connection = usbManager.openDevice(device);
            serialPort = UsbSerialDevice.createUsbSerialDevice(device, connection);

            if (serialPort != null) {
                serialPort.open();
                serialPort.setBaudRate(19200);
                serialPort.setDataBits(UsbSerialInterface.DATA_BITS_8);
                serialPort.setStopBits(UsbSerialInterface.STOP_BITS_1);
                serialPort.setParity(UsbSerialInterface.PARITY_NONE);
            }
        } else {
            System.err.println("Device not found");
        }
    }

    public void readSerialPort(UsbReadCallback callbackFunction) {
      // Привязываем переданный callback
          this.callbackFunction = callbackFunction;

          if (serialPort != null) {
              // Читаем данные с порта
              serialPort.read(mCallback);
          }
    }

    public final UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {
        @Override
        public void onReceivedData(byte[] data) {
            String receivedDataHex = bytesToHex(data);
            if (callbackFunction != null) {
              callbackFunction.onReceived(receivedDataHex);
            }
        }
    };

    private String bytesToHex(byte[] bytes) {
        StringBuilder hexString = new StringBuilder();
        for (byte b : bytes) {
            String hex = Integer.toHexString(b & 0xFF);
            if (hex.length() == 1) {
                hexString.append('0');
            }
            hexString.append(hex);
        }
        return hexString.toString();
    }

    public void close() {
        if (serialPort != null) {
            try {
                if (isTransmitting()) {
                    waitForTransmissionToComplete();
                }
                serialPort.close();
            } catch (InterruptedException e) {
              System.err.println("close() " + e);
            } finally {
                serialPort = null;
            }
        }
    }

    private boolean isTransmitting() {
        return isTransmitting;
    }

    private void waitForTransmissionToComplete() throws InterruptedException {
        while (isTransmitting()) {
            Thread.sleep(50);
        }
    }

    public void sendMessage(String message) {
        if (serialPort != null && message != null) {
            byte[] data = message.getBytes();
            isTransmitting = true;
            serialPort.write(data);
            isTransmitting = false;
        } else {
            System.err.println("Serial port is not initialized or message is null");
        }
    }

    public interface UsbDevicesCallback {
        void onResult(String devicesJson);
    }

    public interface UsbReadCallback {
        void onReceived(String data);
    }
}

我想在“onReceivedData”函数中在消息到达时发送响应。

Answer 1

原来是我发错了。需要不要通过 getBytes 转换为字节，而是通过

“3E8C060102010202978884AD978885F264”.match(/.{1,2}/g).map(byte => parseInt(byte, 16)) 这是在javascript中