Kotlin没有互联网警报盒

Question

我刚开始学习Kotlin，我目前正在开发一个基于WebView的应用程序，如果应用程序打开后，我需要显示一个警告框。我怎么能在科特林做到这一点？

注意:我已经检查过许多堆栈溢出问题，但所有答案都是针对java而不是Kotlin的。另外，我只是个初学者，所以请用简单的方式写下答案，这样我才能理解。抱歉，英语不好

Answer 1

 private fun checkConnectivity() {
        val manager = this.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val activeNetwork = manager.activeNetworkInfo

        if (null == activeNetwork) {
            val dialogBuilder = AlertDialog.Builder(this)
            val intent = Intent(this, MainActivity::class.java)
            // set message of alert dialog
            dialogBuilder.setMessage("Make sure that WI-FI or mobile data is turned on, then try again")
                // if the dialog is cancelable
                .setCancelable(false)
                // positive button text and action
                .setPositiveButton("Retry", DialogInterface.OnClickListener { dialog, id ->
                    recreate()
                })
                // negative button text and action
                .setNegativeButton("Cancel", DialogInterface.OnClickListener { dialog, id ->
                    finish()
                })

            // create dialog box
            val alert = dialogBuilder.create()
            // set title for alert dialog box
            alert.setTitle("No Internet Connection")
            alert.setIcon(R.mipmap.ic_launcher)
            // show alert dialog
            alert.show()
        }
    }

还将此权限添加到报表中

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

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

这应该足以显示一个对话框，如果你的应用程序没有互联网连接。

Answer 2

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.net.ConnectivityManager

open class ConnectionCheck:BroadcastReceiver() {

    override fun onReceive(context: Context?, intent: Intent?) {
        if (connectivityReceiverListener != null) {
            connectivityReceiverListener!!.onNetworkConnectionChanged(
                isConnectedOrConnecting(
                    context!!
                )
            )
        }
    }

    private fun isConnectedOrConnecting(context: Context): Boolean {
        val connMgr = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val networkInfo = connMgr.activeNetworkInfo
        return networkInfo != null && networkInfo.isConnectedOrConnecting
    }

    interface ConnectivityReceiverListener {
        fun onNetworkConnectionChanged(isConnected: Boolean)
    }

    companion object {
        var connectivityReceiverListener: ConnectivityReceiverListener? = null
    }
}

这是互联网连接活动。在您想要检查internet连接的每一个活动中，该活动都应该扩展ConnectionCheck.ConnectivityReceiverListener。

不要忘记将<uses-permission android:name="android.permission.INTERNET"/>放在清单中。