Android Kotlin:如果网络断开连接,则使用ConnectionManager检查网络状态将返回null。怎么会?
我尝试使用以下功能检查网络的状态(已连接或已断开):Android Kotlin:如果网络断开连接,则使用ConnectionManager检查网络状态将返回null。怎么会?,android,kotlin,connectivity,Android,Kotlin,Connectivity,我尝试使用以下功能检查网络的状态(已连接或已断开): // Check Network status private fun isNetworkAvailable(): Boolean { val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) return if (connectivityManager is ConnectivityManager) { val netwo
// Check Network status
private fun isNetworkAvailable(): Boolean {
val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE)
return if (connectivityManager is ConnectivityManager) {
val networkInfo = connectivityManager.activeNetworkInfo
networkInfo.isConnected
}
else false
}
这给了我一个机会
java.lang.IllegalStateException:networkInfo不能为空-错误
在断开网络的情况下运行时。为什么?我怎样才能解决这个问题 根据activeNetworkInfo
可能为空:
返回有关当前活动的默认数据网络的详细信息。什么时候
已连接,此网络是传出连接的默认路由。
在启动网络之前,应始终检查isConnected()
交通。当没有默认网络时,这可能返回null
要确保它不会崩溃,请使用以下命令:
private fun isNetworkAvailable(): Boolean {
val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE)
return if (connectivityManager is ConnectivityManager) {
val networkInfo: NetworkInfo? = connectivityManager.activeNetworkInfo
networkInfo?.isConnected ?: false
} else false
}
最简单的方法之一是,向上下文类添加一个扩展,如下所示
val Context.isConnected: Boolean
get() {
return (getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager)
.activeNetworkInfo?.isConnected == true
}
现在你可以在活动中使用它,比如
if (!isConnected) {
// connection is not available...
}
您可以在活动、片段或上下文中的任何地方使用这种方式 使用此代码,肯定会有帮助
getActiveNetwork
在API 29中已被弃用,因此这是最好的解决方案:
fun isInternetAvailable(context: Context): Boolean {
var result = false
val connectivityManager =
context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
val networkCapabilities = connectivityManager.activeNetwork ?: return false
val actNw =
connectivityManager.getNetworkCapabilities(networkCapabilities) ?: return false
result = when {
actNw.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) -> true
actNw.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) -> true
actNw.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET) -> true
else -> false
}
} else {
connectivityManager.activeNetworkInfo?.run {
result = when (type) {
ConnectivityManager.TYPE_WIFI -> true
ConnectivityManager.TYPE_MOBILE -> true
ConnectivityManager.TYPE_ETHERNET -> true
else -> false
}
}
}
return result
}
我错误地认为.isConnected将始终返回布尔值。networkInfo已弃用。检查此项以获取更新响应:
fun isInternetAvailable(context: Context): Boolean {
var result = false
val connectivityManager =
context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
val networkCapabilities = connectivityManager.activeNetwork ?: return false
val actNw =
connectivityManager.getNetworkCapabilities(networkCapabilities) ?: return false
result = when {
actNw.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) -> true
actNw.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) -> true
actNw.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET) -> true
else -> false
}
} else {
connectivityManager.activeNetworkInfo?.run {
result = when (type) {
ConnectivityManager.TYPE_WIFI -> true
ConnectivityManager.TYPE_MOBILE -> true
ConnectivityManager.TYPE_ETHERNET -> true
else -> false
}
}
}
return result
}