【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：

 
...
...

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

...
...
 

app 層級 build.gradle

android {
    compileSdk 33

    ...
    ...

    buildFeatures {
        viewBinding true
    }

    ...
    ...

}

activity_main.xml：

 
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtHello"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
 

MainActivity.kt

 
...
...
class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        val view = binding.root
        setContentView(view)
    }

    override fun onResume() {
        super.onResume()
        val filter = IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)
        registerReceiver(connectivityReceiver, filter)
    }

    override fun onPause() {
        super.onPause()
        unregisterReceiver(connectivityReceiver)
    }

    fun updateTextView(message: String) {
        binding.txtHello.text = message
    }
    
    
    ...
    ...
    
    private val connectivityReceiver = object : BroadcastReceiver() {
        override fun onReceive(context: Context?, intent: Intent?) {
            val connectivityManager = context?.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val networkInfo = connectivityManager.activeNetworkInfo
            if (networkInfo != null && networkInfo.isConnected) {
                (context as MainActivity).updateTextView("已連線")
            } else {
                (context as MainActivity).updateTextView("已斷線")
            }
        }
    }

}
...
...
 

相關筆記 ----

【Android】用 PING 偵測網路連線狀況

【Kotlin】視圖綁定 ViewBinding