2023-02-05

【Kotlin】以 BroadcastReceiver 通知裝置網路連線狀態 -- 適用 API28(含)之前

參考資料 ----
ConnectivityManager
NetworkInfo


授予 app 權限

AndroidManifest.xml
  1.  
  2. ...
  3. ...
  4.  
  5. <uses-permission android:name="android.permission.INTERNET"/>
  6. <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
  7.  
  8. ...
  9. ...
  10.  


app 層級 build.gradle
  1. android {
  2. compileSdk 33
  3.  
  4. ...
  5. ...
  6.  
  7. buildFeatures {
  8. viewBinding true
  9. }
  10.  
  11. ...
  12. ...
  13.  
  14. }


activity_main.xml
  1.  
  2. <?xml version="1.0" encoding="utf-8"?>
  3. <androidx.constraintlayout.widget.ConstraintLayout
  4. xmlns:android="http://schemas.android.com/apk/res/android"
  5. xmlns:app="http://schemas.android.com/apk/res-auto"
  6. xmlns:tools="http://schemas.android.com/tools"
  7. android:layout_width="match_parent"
  8. android:layout_height="match_parent"
  9. tools:context=".MainActivity">
  10.  
  11. <TextView
  12. android:layout_width="wrap_content"
  13. android:layout_height="wrap_content"
  14. android:id="@+id/txtHello"
  15. android:text="Hello World!"
  16. app:layout_constraintBottom_toBottomOf="parent"
  17. app:layout_constraintEnd_toEndOf="parent"
  18. app:layout_constraintStart_toStartOf="parent"
  19. app:layout_constraintTop_toTopOf="parent" />
  20.  
  21. </androidx.constraintlayout.widget.ConstraintLayout>
  22.  



MainActivity.kt
  1.  
  2. ...
  3. ...
  4. class MainActivity : AppCompatActivity() {
  5.  
  6. private lateinit var binding: ActivityMainBinding
  7.  
  8. override fun onCreate(savedInstanceState: Bundle?) {
  9. super.onCreate(savedInstanceState)
  10. binding = ActivityMainBinding.inflate(layoutInflater)
  11. val view = binding.root
  12. setContentView(view)
  13. }
  14.  
  15. override fun onResume() {
  16. super.onResume()
  17. val filter = IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)
  18. registerReceiver(connectivityReceiver, filter)
  19. }
  20.  
  21. override fun onPause() {
  22. super.onPause()
  23. unregisterReceiver(connectivityReceiver)
  24. }
  25.  
  26. fun updateTextView(message: String) {
  27. binding.txtHello.text = message
  28. }
  29. ...
  30. ...
  31. private val connectivityReceiver = object : BroadcastReceiver() {
  32. override fun onReceive(context: Context?, intent: Intent?) {
  33. val connectivityManager = context?.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
  34. val networkInfo = connectivityManager.activeNetworkInfo
  35. if (networkInfo != null && networkInfo.isConnected) {
  36. (context as MainActivity).updateTextView("已連線")
  37. } else {
  38. (context as MainActivity).updateTextView("已斷線")
  39. }
  40. }
  41. }
  42.  
  43. }
  44. ...
  45. ...
  46.  


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