在 Android Kotlin 上检查网络连接的问题

Question

我调用以下函数onCreate，当我在进行此活动时打开和关闭设备上的网络连接时，它会完美地显示该消息。但是，当我在设备上的网络关闭时打开此活动时，它不会显示网络已关闭的消息，而当我在网络打开时打开此活动时，它会显示我正在运行的消息连接到网络。

       private fun checkConnection() {
        connectivity = CheckConnectivity(application)
        connectivity.observe(this, { isConnected ->
            if (isConnected) {
          Toast.makeText(this,"You are connected to the internet",Toast.LENGTH_SHORT).show()
            } else {
           Toast.makeText(this,"You are NOT connected to the internet",Toast.LENGTH_SHORT).show()
            }
        })
    }

以下是CheckConnectivity.kt

    class CheckConnectivity(private val connectivityManager: ConnectivityManager) :
    LiveData<Boolean>() {

    constructor(application: Application) : this(
        application.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    )

    private val networkCallback = @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    object: ConnectivityManager.NetworkCallback(){

        override fun onAvailable(network: Network) {
            super.onAvailable(network)
            postValue(true)
        }

        override fun onLost(network: Network) {
            super.onLost(network)
            postValue(false)
        }
    }

    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    override fun onActive() {
        super.onActive()
        val builder=NetworkRequest.Builder()
        connectivityManager.registerNetworkCallback(builder.build(),networkCallback)
    }

    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    override fun onInactive() {
        super.onInactive()
        connectivityManager.unregisterNetworkCallback(networkCallback)
    }
}

Answer 1

这可以通过调用来完成onUnavailable()，但遗憾的是，该函数没有响应。检查如果未找到 Wi-Fi AP，则不会调用 NetworkCallback 的 onUnavailable() 方法

但你可以通过添加isconnected()到你的MainActivity.kt. 我知道这不是您正在寻找的答案，但通过这样做您的问题将会得到解决，欢呼。

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        checkConnection()
    }


    override fun onStart() {
        super.onStart()
        Toast.makeText(this, if (isConnected()) "You are connected to the internet" else "You are NOT connected to the internet", Toast.LENGTH_SHORT
        ).show()
    }
    
    private fun checkConnection() {
        val connectivity = CheckConnectivity(application)
        connectivity.observe(this, { isConnected ->
            Log.d("testTag", "checkConnection: Observer Called")
            if (isConnected) {
                Toast.makeText(this, "You are connected to the internet", Toast.LENGTH_SHORT).show()
            } else {
                Toast.makeText(this, "You are NOT connected to the internet", Toast.LENGTH_SHORT)
                    .show()
            }
        })
    }

    private fun isConnected(): Boolean {
        var connected = false
        try {
            val cm =
                applicationContext.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val nInfo = cm.activeNetworkInfo
            connected = nInfo != null && nInfo.isAvailable && nInfo.isConnected

            return connected
        } catch (e: Exception) {
            Log.e("Connectivity Exception", e.message!!)
        }
        return connected
    }
}