[Kotlin] Android 接收廣播事件 BroadcastReceiver

在 Android 中可以繼承 BroadcastReceiver 來處理系統事件，這裡我們註冊兩個事件：接上電源和移除電源

    
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.widget.Toast

class MyBroadcastReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        when (intent.action) {
            Intent.ACTION_POWER_CONNECTED -> {
                Toast.makeText(context, "已連接電源", Toast.LENGTH_SHORT).show()
            }

            Intent.ACTION_POWER_DISCONNECTED -> {
                Toast.makeText(context, "已中斷電源連接", Toast.LENGTH_SHORT).show()
            }
        }
    }
}
    

然後就是在 MainActivity.kt 中註冊接收器，在 registerReceiver 方法中需要傳入事件，這裡一樣填入剛剛註冊的兩個事件，然後覆寫 onDestroy 方法釋放接收器：

    
import android.content.Intent
import android.content.IntentFilter
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge

class MainActivity : ComponentActivity() {

    private val receiver = MyBroadcastReceiver()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()

        registerReceiver(receiver, IntentFilter().apply {
            addAction(Intent.ACTION_POWER_CONNECTED)
            addAction(Intent.ACTION_POWER_DISCONNECTED)
        })

        setContent {
        }
    }

    override fun onDestroy() {
        super.onDestroy()
        unregisterReceiver(receiver)
    }
}
    

執行後連接電源或是移除就會看到 Toast 通知了！

參考資料：
Android Developers - BroadcastReceiver
Android Developers - Broadcasts overview
Android Developers - <receiver>