我使用USB接收器处理与通过USB连接到手机的温度传感器的通信。
到目前为止一切正常,但如果我重新启动手机,即使没有任何USB设备,应用程序会在重新启动后立即弹出 USB-Permission弹出窗口在那个时刻附在电话上。
有没有人知道导致这个奇怪问题的原因是什么?
[编辑:我很抱歉,该应用不会要求USB权限,弹出窗口询问我是否要打开应用,如果"此设备是连接"但显然没有附加设备。]
这是USB接收器的代码:
//Initial USB Settings Receiver
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
@Override
public void onReceive(final Context context, final Intent intent) {
final String action = intent.getAction();
if (ACTION_USB_PERMISSION.equals(action)) {
synchronized (this) {
final UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
// is usb permission has been granted, try to open a connection
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
if (device != null) {
// call method to set up device communication
Constants result = mcp2221.open();
if (result != Constants.SUCCESS) {
//nothing by now
} else {
openConnectionToMCP2221();
}
}
}
}
}
if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
// close the connection and release all resources
closeAllResources();
// leave a bit of time for the COM thread to close
try {
Thread.sleep(20);
}catch(InterruptedException e){e.printStackTrace();}
mcp2221Comm = null;
Toast.makeText(getApplicationContext(), "Device detached",
Toast.LENGTH_SHORT).show();
}
if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
final UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (device != null) {
Toast.makeText(getApplicationContext(), "Device attached",
Toast.LENGTH_SHORT).show();
mStopUSBThread=false;
// only try to connect if an MCP2221 is attached
if (device.getVendorId() == MCP2221_VID && device.getProductId() == MCP2221_PID) {
Constants result = mcp2221.open();
switch (result) {
case SUCCESS:
openConnectionToMCP2221();
break;
case CONNECTION_FAILED:
Toast.makeText(getApplicationContext(), "ERROR: connection failed", Toast.LENGTH_SHORT).show();
break;
case NO_USB_PERMISSION:
Toast.makeText(getApplicationContext(), "ERROR: no USB permission", Toast.LENGTH_SHORT).show();
mcp2221.requestUsbPermission(mPermissionIntent);
break;
default:
break;
}
}
}
}
}
};
这是onCreate()部分:
//USB Connection
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
final IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
registerReceiver(mUsbReceiver, filter);
//Checking if theres a Device already connected
.......
答案 0 :(得分:0)
知道了! 这是一个
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"/>
</intent-filter>
在<activity>
下的AndroidManifest.xml中声明。
我不完全明白,为什么它会导致这个Bug,但删除它会保留我的应用程序的功能,同时摆脱问题。
可能只有“消极”方面,现在应用程序不会要求打开传感器是否已连接到手机。