应用程序在通过 UsbManager 授予连接 [设备] 的权限时崩溃

问题描述

我正在学习如何使用 UsbManager 文档和 UsbSerial 库通过 USB 将 arduino 连接到 android 进行通信。活动打开，当我点击一个按钮与 Arduino 建立连接时，会弹出一个权限提示“Arduino 想要与 null 连接”，如果允许，应用程序崩溃。我尝试了许多在线可用的代码，但问题仍然存在。这是活动java代码。我删除了一些与此功能无关的代码。请询问任何其他必要的信息。谢谢...

SerialView.java

public class SerialView extends AppCompatActivity {
    PendingIntent mPermissionIntent;
    UsbDevice usbdevice;
    UsbManager usbManager;
    private static final String ACTION_USB_PERMISSION = "com.xyz.arduino.USB_PERMISSION";

    UsbSerialDevice serialPort;
    private static final int targetvendorID = 2341;  //Arduino Uno
    private static final int targetProductID = 43;

   
    TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_serial_view);
        textView=(TextView) findViewById(R.id.streamdisplay);
       

    }


    public void onClickStart(View view) {
        usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
       
        mPermissionIntent = PendingIntent.getbroadcast(this,new Intent(
                ACTION_USB_PERMISSION),0);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        registerReceiver(mUsbReceiver,filter);
       
        HashMap<String,UsbDevice> deviceList = usbManager.getDeviceList();
        Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();

        while (deviceIterator.hasNext()) {
            UsbDevice device = deviceIterator.next();
            usbManager.requestPermission(device,mPermissionIntent);
            if (device.getvendorId() == targetvendorID) {
                if (device.getProductId() == targetProductID) {
                    usbdevice = device;
                }
            }
        }

    }
    private final broadcastReceiver mUsbReceiver = new broadcastReceiver() {
              //broadcast Receiver to automatically start and stop the Serial connection.
        @Override
        public void onReceive(Context context,Intent intent) {
            if (intent.getAction().equals(ACTION_USB_PERMISSION)) {
                boolean granted =
                        intent.getExtras().getBoolean(UsbManager.EXTRA_PERMISSION_GRANTED);
                if (granted) {
                    UsbDeviceConnection connection = usbManager.openDevice(usbdevice);
                    serialPort = UsbSerialDevice.createUsbSerialDevice(usbdevice,connection);
                    if (serialPort != null) {
                        if (serialPort.open()) { //Set Serial Connection Parameters.
                            //Enable Buttons in UI
                            serialPort.setBaudrate(9600);
                            serialPort.setDataBits(UsbSerialInterface.DATA_BITS_8);
                            serialPort.setStopBits(UsbSerialInterface.STOP_BITS_1);
                            serialPort.setParity(UsbSerialInterface.PARITY_NONE);
                            serialPort.setFlowControl(UsbSerialInterface.FLOW_CONTROL_OFF);

                            UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {
                                //Defining a Callback which triggers whenever data is read.
                                @Override
                                public void onReceivedData(byte[] arg0) {
                                    String data = null;
                                    try {
                                        data = new String(arg0,"UTF-8");
                                        data.concat("/n");
                                        tvAppend(textView,data);
                                    } catch (UnsupportedEncodingException e) {
                                        e.printstacktrace();
                                    }
                                }
                            };
                            serialPort.read(mCallback);
                            tvAppend(textView,"Serial Connection Opened!\n");

                        } else {
                            Log.d("SERIAL","PORT NOT OPEN");
                        }
                    } else {
                        Log.d("SERIAL","PORT IS NULL");
                    }
                } else {
                    Log.d("SERIAL","PERM NOT GRANTED");
                }
            } else if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) {
                onClickStart(findViewById(R.id.startconbut));
            } else if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_DETACHED)) {
                onClickStop(findViewById(R.id.endconbut));
            }
        };
    };

    private void tvAppend(TextView tv,CharSequence text) { final TextView ftv = tv; final CharSequence ftext = text; runOnUiThread(new Runnable() { @Override public void run() { ftv.append(ftext); } }); }
    public void onClickStop(View view){
        serialPort.close();
        Toast.makeText(SerialView.this,"Arduino disconnected",Toast.LENGTH_LONG)
                .show();
    }

解决方法

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