如果你需要检查网络连接，使用ping到服务器的方法:

public boolean checkIntCON() {
    try {
        Process ipProcess = Runtime.getRuntime().exec("/system/bin/ping -c 1 8.8.8.8");
        return (ipProcess.waitFor() == 0);
    }
    catch (IOException e)          { e.printStackTrace(); }
    catch (InterruptedException e) { e.printStackTrace(); }
    return false;
}

您可以使用端口进行检查

public boolean checkIntCON() {
    try {
        Socket sock = new Socket();
        SocketAddress sockaddr = new InetSocketAddress("8.8.8.8", 80); 
        // port will change according to protocols

        sock.connect(sockaddr, 1250);
        sock.close();

        return true;
    } catch (IOException e) { return false; }
}

我在这里看到了很多过时的答案，所以我决定加入我的答案。

由于Android 10 (API级别29)getActiveNetworkInfo()已弃用，谷歌建议我们使用NetworkCallbacks而不是针对Android 10及更高版本的应用程序。

关于阅读网络状态的文档提供了一些关于如何使用NetworkCallback的信息，但我没有设法找到一个很好的代码示例，整个事情的工作，所以这里是我提出的代码，我们在我们的应用程序中使用:

import android.content.Context
import android.net.ConnectivityManager
import android.net.LinkProperties
import android.net.Network
import android.net.NetworkCapabilities
import com.fieldontrack.kmm.common.network.ConnectivityMonitor
import com.fieldontrack.kmm.entities.connectivity.NetworkType
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow

class ConnectivityMonitorImpl(appContext: Context) : ConnectivityMonitor {
    private val connectivityManager = appContext.getSystemService(ConnectivityManager::class.java)
    private val networkCallback = object : ConnectivityManager.NetworkCallback() {
        override fun onAvailable(network: Network) =
            connectivityManager.getNetworkCapabilities(network)?.let { networkCapabilities ->
                updateConnectionStatus(networkCapabilities = networkCapabilities)
                updateNetworkType(networkCapabilities = networkCapabilities)
            } ?: run {
                _isConnectedState.value = true
            }

        override fun onLost(network: Network) {
            // Do not check for NetworkCapabilities here, as they might be wrong.
            // If we get this callback, we're certain that we've lost connection.
            _isConnectedState.value = false
            _networkTypeState.value = NetworkType.Unknown
        }

        override fun onCapabilitiesChanged(
            network: Network,
            networkCapabilities: NetworkCapabilities
        ) {
            updateConnectionStatus(networkCapabilities = networkCapabilities)
            updateNetworkType(networkCapabilities = networkCapabilities)
        }

        override fun onLinkPropertiesChanged(
            network: Network,
            linkProperties: LinkProperties
        ) = Unit
    }
    private val _isConnectedState = MutableStateFlow(false)
    private val _networkTypeState = MutableStateFlow(NetworkType.Unknown)

    override val isConnectedState: StateFlow<Boolean> = _isConnectedState
    override val networkTypeState: StateFlow<NetworkType> = _networkTypeState

    override val isConnected: Boolean
        get() = _isConnectedState.value

    override val networkType: NetworkType
        get() = _networkTypeState.value

    init {
        startMonitoring()
    }

    override fun startMonitoring() =
        connectivityManager.registerDefaultNetworkCallback(networkCallback)

    override fun stopMonitoring() =
        connectivityManager.unregisterNetworkCallback(networkCallback)

    private fun updateConnectionStatus(networkCapabilities: NetworkCapabilities) {
        val isConnected =
            networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)

        _isConnectedState.value = isConnected
    }

    private fun updateNetworkType(networkCapabilities: NetworkCapabilities) {
        val networkType = when {
            networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) -> NetworkType.WiFi
            networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) -> NetworkType.Cellular
            else -> NetworkType.Unknown
        }

        _networkTypeState.value = networkType
    }
}

ConnectivityMonitor界面非常简单:

interface ConnectivityMonitor {
    val isConnected: Boolean
    val networkType: NetworkType

    val isConnectedState: StateFlow<Boolean>
    val networkTypeState: StateFlow<NetworkType>
    
    fun startMonitoring()
    fun stopMonitoring()
}

NetworkType只是一个简单的枚举:

enum class NetworkType { Unknown, Cellular, WiFi }

据我测试，无论应用程序是在后台还是前台，这都是可行的。

这种方法为您提供了一个非常快速的方法(用于实时反馈)或较慢的方法(用于需要可靠性的一次性检查)。

public boolean isNetworkAvailable(bool SlowButMoreReliable) {
    bool Result = false; 
    try {
        if(SlowButMoreReliable){
            ConnectivityManager MyConnectivityManager = null;
            MyConnectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

            NetworkInfo MyNetworkInfo = null;
            MyNetworkInfo = MyConnectivityManager.getActiveNetworkInfo();

            Result = MyNetworkInfo != null && MyNetworkInfo.isConnected();

        } else
        {
            Runtime runtime = Runtime.getRuntime();
            Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");

            int i = ipProcess.waitFor();

            Result = i== 0;

        }

    } catch(Exception ex)
    {
        //Common.Exception(ex); //This method is one you should have that displays exceptions in your log
    }
    return Result;
}

要让getActiveNetworkInfo()工作，您需要向清单中添加以下内容。

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

不要忘记将这些权限添加到您的manifest:

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

看一下ConnectivityManager类。您可以使用这个类来获取主机上活动连接的信息。http://developer.android.com/reference/android/net/ConnectivityManager.html

编辑:你可以使用

Context.getSystemService(Context.CONNECTIVITY_SERVICE)
    .getNetworkInfo(ConnectivityManager.TYPE_MOBILE) 

or

Context.getSystemService(Context.CONNECTIVITY_SERVICE)
    .getNetworkInfo(ConnectivityManager.TYPE_WIFI) 

并解析返回NetworkInfo对象的DetailedState枚举

EDIT EDIT:查看是否可以访问主机

Context.getSystemService(Context.CONNECTIVITY_SERVICE)
    .requestRouteToHost(TYPE_WIFI, int hostAddress)

显然，我使用Context.getSystemService(Context.CONNECTIVITY_SERVICE)作为代理来表示

ConnectivityManager cm = Context.getSystemService(Context.CONNECTIVITY_SERVICE);
cm.yourMethodCallHere();