如何解决片段中接收NFC的应用程序创建了托管活动的新实例
打招呼中的人们
好吧,我得到了一个托管3个片段的活动(使用navController) 我需要读取其中一个托管片段(GameSessionFragment)中的NFC标签ID(EXTRA_ID)
我的问题是,每次我扫描新的NFC标签时,托管该片段(主机)的活动都会再次“创建”,以便使我脱离呈现的片段,并导航到“主机”活动,我试图避免重新创建主机活动的任何想法如何实现?
如果我不清楚,或者您认为我对我的问题可能有更好的解释,请在上方写上, 另外,对不起我的英语。
这是我的代码:
清单:
<activity android:name=".Host" >
<intent-filter>
<action android:name="android.nfc.action.TAG_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
主机活动:
class Host : AppCompatActivity() {
var fragment: Fragment? = null
private var mAdapter: NfcAdapter? = null
private var mPendingIntent: PendingIntent? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_host)
//for hide the actionBar (contains Fragment name) on top of the screen
val actionBar = supportActionBar
actionBar?.hide()
val navController = Navigation.findNavController(this,R.id.nav_host_fragment)
val navView = findViewById<BottomNavigationView>(R.id.nav_view)
navView?.setupWithNavController(navController)
NavigationUI.setupWithNavController(navView,navController)
//tries to stop poping the activity each time NFC Tag scanned
mAdapter = NfcAdapter.getDefaultAdapter(this)
mPendingIntent = PendingIntent.getActivity(
this,Intent(this,javaClass).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP),0
)
//toGameSession(whatToDO)
}
override fun onActivityResult(requestCode: Int,resultCode: Int,data: Intent?) {
super.onActivityResult(requestCode,resultCode,data)
for (fragment in supportFragmentManager.fragments) {
fragment.onActivityResult(requestCode,data)
}
}
override fun onNewIntent(intent: Intent) {
super.onNewIntent(intent)
if (NfcAdapter.ACTION_NDEF_DISCOVERED == intent.action) {
intent.getParcelableArrayExtra(NfcAdapter.EXTRA_ID)?.also { rawMessages ->
val messages: List<NdefMessage> = rawMessages.map { it as NdefMessage }
// Process the messages array.
println(messages)
if (fragment is UserStatusFragment) {
val my: UserStatusFragment = fragment as UserStatusFragment
// Pass intent or its data to the fragment's method
my.processNFC(intent.getStringExtra(messages.toString()))
}
}
}
}
}
这是我要接收并使用NFC Extra_ID的片段
GameSessionFragment
class GameSessionFragment : Fragment() {
// TODO: Rename and change types of parameters
private var param1: String? = null
private var param2: String? = null
lateinit var nfcTagId : String
private var mNfcAdapter: NfcAdapter? = null
private var mPendingIntent: PendingIntent? = null
private var mNdefPushMessage: NdefMessage? = null
var mAuth: FirebaseAuth? = null
lateinit var firebaseUser: FirebaseUser
private lateinit var databaseReference: DatabaseReference
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onViewCreated(view: View,savedInstanceState: Bundle?) {
super.onViewCreated(view,savedInstanceState)
getNfcTagID()
}
override fun onCreateView(
inflater: LayoutInflater,container: ViewGroup?,savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_game_session,container,false)
}
private fun getNfcTagID(){
val tagId : ByteArray? = activity?.intent?.getByteArrayExtra(NfcAdapter.EXTRA_ID)
if (tagId != null){
nfcTagId = tagId?.toHexString().toString()
tv_status.text = nfcTagId
}
}
fun ByteArray.toHexString() = joinToString("") { "%02x".format(it) }
fun questPartFinish(questPart: String,useruid: String) {
// val rootRef = FirebaseDatabase.getInstance().reference
// val scoreRef = rootRef.child("Quests").child(useruid).child("$questPart+QuestItemScanned")
// scoreRef.runTransaction(object : Handler(),Transaction.Handler {
// override fun doTransaction(mutableData: MutableData): Transaction.Result {
// val ifFinish =
// mutableData.getValue(Boolean::class.java) ?: return Transaction.success(mutableData)
//
// mutableData.value = true
//// if (operation == "increaseScore") {
//// mutableData.value = score + 50
//// } else if (operation == "decreaseScore") {
//// mutableData.value = score - 1
//// }
// return Transaction.success(mutableData)
// }
//
// override fun onComplete(
// databaseError: DatabaseError?,// b: Boolean,// dataSnapshot: DataSnapshot?
// ) {
// }
//
// override fun publish(p0: LogRecord?) {
// TODO("Not yet implemented")
// }
//
// override fun flush() {
// TODO("Not yet implemented")
// }
//
// override fun close() {
// TODO("Not yet implemented")
// }
// })
databaseReference.child("Quests").child(useruid)
.child("$questPart" + "QuestItemScanned").setValue(true)
}
}
我还在这里Application receiving NFC always pops up new instance in front
但没有意识到实际要做的事情。
我读到有关使用的信息
mNfcAdapter!!.disableForegroundDispatch(getActivity())
但不确定那件事是否也会影响我。
更新:
感谢:安德鲁
非常感谢!! “ enableReaderMode”似乎就像我需要的东西一样,我成功读取了标签ID,但是同时发生了两个问题,当我扫描NFC标签时,我可以在“ println”中看到标签ID,到目前为止一切正常,即时通讯成功读取它,但是当我尝试将其传递到片段中的TextView时,它仅在刷新片段时才会发生,(还有第二个问题)我看到了那个textview几秒钟,但随后所有我的布局消失了(在“主机活动”中的所有片段中),
得到该消息“只有创建视图层次结构的原始线程才能触摸其视图”
我可以看到那些片段内部的功能,它只是消失的布局,希望您能理解我的意愿。能够帮助我解决我的问题,如果您认为有更好的方式来描述问题,我们欢迎您发言
感谢所有来帮助我们的人!
工作乐趣 您所需要的! '''
var mNfcAdapter:NfcAdapter? =空
fun ByteArray.toHexString() = joinToString("") { "%02x".format(it) }
fun scanForNfcTagId(activity : Activity){
val options = Bundle()
// READER_PRESENCE_CHECK_DELAY is a work around for a Bug in some NFC implementations.
options.putInt(NfcAdapter.EXTRA_READER_PRESENCE_CHECK_DELAY,1);
mNfcAdapter = NfcAdapter.getDefaultAdapter(activity)
val flags =
NfcAdapter.FLAG_READER_NO_PLATFORM_SOUNDS or
NfcAdapter.FLAG_READER_NFC_A or
NfcAdapter.FLAG_READER_NFC_B or
NfcAdapter.FLAG_READER_NFC_F or
NfcAdapter.FLAG_READER_NFC_V or
NfcAdapter.FLAG_READER_NFC_BARCODE
mNfcAdapter!!.enableReaderMode(activity,NfcAdapter.ReaderCallback { tag ->
activity?.runOnUiThread {
Log.d("WTF","Tag discovered")
nfcTagId = (tag.id).toHexString()
Toast.makeText(
activity,"tag detected",Toast.LENGTH_SHORT
).show()
if (!actualQuest.firstQuestItemScanned) {
hatCallBackAction(activity)
} else if (!actualQuest.secondQuestItemScanned) {
println("scan for pants")
pantsCallBackAction(activity)
} else if (!actualQuest.thirdQuestItemScanned) {
println("scan for shirt")
shirtCallBackAction(activity)
} else {
println("actualQuest" + actualQuest)
Toast.makeText(
activity,"Quest is Finish! no more to search here",Toast.LENGTH_LONG
).show()
}
}
},flags,null)
}
'''
解决方法
使用更新更好的enableReaderMode
API进行NFC https://developer.android.com/reference/android/nfc/NfcAdapter#enableReaderMode(android.app.Activity,%20android.os.Bundle)
这会在您的应用程序中创建一个新线程来处理发现标签的情况,避免了使用Intents
获取NFC数据时发生的创建/重新创建/暂停/恢复活动。
然后在onTagDiscovered
回调方法中,对getId
对象使用Tag
https://developer.android.com/reference/android/nfc/Tag#getId()以获取与Extra_ID
相同的数据
在https://stackoverflow.com/a/64441986/2373819处使用enableReaderMode
的示例
更新
如答案中所述,将创建一个新线程来处理NFC数据,并且只有UI线程才能更新UI
也在示例代码的注释中
// This gets run in a new thread on Tag detection
// Thus cannot directly interact with the UI Thread
public void onTagDiscovered(Tag tag) {
因此,您需要使用一种方法来在线程之间传递数据。
一种简单的方法是使用runOnUIThread
https://developer.android.com/reference/android/app/Activity#runOnUiThread(java.lang.Runnable)
例如
runOnUiThread(new Runnable() {
@Override
public void run() {
// Set the value of the ID to the textview
textview.setText(iDtext);
}
});
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