kotlin中的android与USB通信存在问题
我正在尝试在我的android和USB之间通信。我按照android.com的说明操作，但我的智能手机没有要求授权与USB通信。然而，我的智能手机确实能检测到我是否安装了USB。事实上，变量“device”总是空的，我不明白为什么。你知道这个问题吗kotlin中的android与USB通信存在问题,android,kotlin,usb,Android,Kotlin,Usb,我正在尝试在我的android和USB之间通信。我按照android.com的说明操作，但我的智能手机没有要求授权与USB通信。然而，我的智能手机确实能检测到我是否安装了USB。事实上，变量“device”总是空的，我不明白为什么。你知道这个问题吗 var ACTION_USB_ATTACHED :String = “android.hardware.usb.action.USB_DEVICE_ATTACHED” var ACTION_USB_DETACHED :String = “andro
var ACTION_USB_ATTACHED :String = “android.hardware.usb.action.USB_DEVICE_ATTACHED”
var ACTION_USB_DETACHED :String = “android.hardware.usb.action.USB_DEVICE_DETACHED”
var ACTION_USB_PERMISSION :String = “com.android.example.USB_PERMISSION”
class MainActivity : AppCompatActivity(){
var switch_on_off :Switch? = null
var tv_info : TextView? = null
//USB
var mUsbReceiver :UsbReceiver? = null
var mfilter :IntentFilter? = null
var mUsbManager :UsbManager? = null
var mPermissionIntent : PendingIntent? = null
var device :UsbDevice? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
tv_info = findViewById<TextView>(R.id.textView)
switch_on_off = findViewById<Switch>(R.id.switch1)
switch_on_off!!.setChecked(false)
switch_on_off!!.setText("OFF")
//USB
mUsbReceiver = UsbReceiver()
mfilter = IntentFilter()
mfilter!!.addAction(ACTION_USB_ATTACHED)
mfilter!!.addAction(ACTION_USB_DETACHED)
registerReceiver(mUsbReceiver, mfilter)
mUsbManager = getSystemService(Context.USB_SERVICE) as UsbManager
//threads
t_switchOnOff.start()
}
val t_switchOnOff = thread(start = false, priority = 10)
{
while(true){
Thread.sleep(300)
this@MainActivity.runOnUiThread(java.lang.Runnable {
if(switch_on_off!!.isChecked()){
switch_on_off!!.setText("ON")
device = intent?.getParcelableExtra<UsbDevice>(UsbManager.EXTRA_DEVICE)
if(device != null)
{
if(!mUsbManager!!.hasPermission(device)){
mPermissionIntent = PendingIntent.getBroadcast(this, 0, Intent(ACTION_USB_PERMISSION), 0);
mUsbManager!!.requestPermission(device, mPermissionIntent);
}
else{
tv_info!!.setText("")
tv_info!!.setText("device USB detected : ${device!!.deviceName} \n
& Authorization accorded")
}
}
else{
tv_info!!.setText("device USB NOT detected \n& usb Detached")
}
}
else{
tv_info!!.setText("")
switch_on_off!!.setText("OFF")
}
})//end this@MainActivity.runOnUiThread(java.lang.Runnable ...
}
}//end thread
class UsbReceiver : BroadcastReceiver() {
override fun onReceive(context: Context?, intent: Intent?) {
val action = intent?.action
var ACTION_USB_PERMISSION :String = "com.android.example.USB_PERMISSION"
if (action!!.equals(ACTION_USB_DETACHED)) {}
if (action!!.equals(ACTION_USB_ATTACHED)){}
if (action!!.equals(ACTION_USB_PERMISSION)){
if (!intent!!.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED,false)) {
//Authoization refused
} else {
//Authorization accepted
}
}
}
}//end class UsbReceiver }
感谢您的帮助实际上，您必须为每个可用的USB设备请求许可，Android官方文档并没有真正强调这一点
// register the broadcast receiver
val manager = getSystemService(Context.USB_SERVICE) as UsbManager
val permissionIntent = PendingIntent.getBroadcast(this, 0, Intent(ACTION_USB_PERMISSION), 0)
val filter = IntentFilter(ACTION_USB_PERMISSION)
registerReceiver(usbReceiver, filter)
for (dev in manager.deviceList)
{
// returns hashmap<String, UsbDevice>
Log.i("TAG", dev.key + " " + dev.value)
// now ask for permission
manager.requestPermission(dev.value, permissionIntent)
}
//注册广播接收器
val manager=getSystemService（Context.USB_服务）作为UsbManager
val permissionIntent=pendingent.getBroadcast（this，0，Intent（ACTION\u USB\u PERMISSION），0）
val filter=IntentFilter（操作\u USB\u权限）
寄存器接收器（usbReceiver，过滤器）
for（manager.deviceList中的开发）
{
//返回哈希映射
Log.i（“标记”，dev.key+“”+dev.value）
//现在请求许可
manager.requestPermission（dev.value、permissionIntent）
}