下面是我用于可达性检查的Kotlin版本，

芬兰湾的科特林MyReachability

object MyReachability {

    private val REACHABILITY_SERVER = "http://google.com" // can be any URL you want

    private fun hasNetworkAvailable(context: Context): Boolean {
        val service = Context.CONNECTIVITY_SERVICE
        val manager = context.getSystemService(service) as ConnectivityManager?
        val network = manager?.activeNetworkInfo
        Log.d(classTag, "hasNetworkAvailable: ${(network != null)}")
        return (network != null)
    }

    fun hasInternetConnected(context: Context): Boolean {
        if (hasNetworkAvailable(context)) {
            try {
                val connection = URL(REACHABILITY_SERVER).openConnection() as HttpURLConnection
                connection.setRequestProperty("User-Agent", "Test")
                connection.setRequestProperty("Connection", "close")
                connection.connectTimeout = 1500
                connection.connect()
                Log.d(classTag, "hasInternetConnected: ${(connection.responseCode == 200)}")
                return (connection.responseCode == 200)
            } catch (e: IOException) {
                Log.e(classTag, "Error checking internet connection", e)
            }
        } else {
            Log.w(classTag, "No network available!")
        }
        Log.d(classTag, "hasInternetConnected: false")
        return false
    }
}

您甚至可以根据策略和限制将REACHABILITY_SERVER作为参数传递，例如，当您在中国时，您可以检查https://baidu.com而不是https://google.com。

调用示例中,

val webLoaderThread = Thread {
   if (MyReachability.hasInternetConnected(this)){
       runOnUiThread {
           //mWebView.loadUrl(LANDING_SERVER) // connected
       }
   } else {
       runOnUiThread {
           //showDialogNoNetwork() // not connected
       }
   }
}
webLoaderThread.start()

安卓系统权限

不要忘记将以下权限添加到你的AndroidManifest.xml中

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

只需创建下面的类来检查internet连接:

public class ConnectionStatus {

    private Context _context;

    public ConnectionStatus(Context context) {
        this._context = context;
    }

    public boolean isConnectionAvailable() {
        ConnectivityManager connectivity = (ConnectivityManager) _context
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivity != null) {
            NetworkInfo[] info = connectivity.getAllNetworkInfo();
            if (info != null)
                for (int i = 0; i < info.length; i++)
                    if (info[i].getState() == NetworkInfo.State.CONNECTED) {
                        return true;
                    }
        }
        return false;
    }
}

该类仅包含一个返回连接状态布尔值的方法。因此，简单来说，如果该方法找到一个到Internet的有效连接，则返回值为true，否则为false，如果没有找到有效连接。

MainActivity中的下面的方法调用前面描述的方法的结果，并提示用户进行相应的操作:

public void addListenerOnWifiButton() {
        Button btnWifi = (Button)findViewById(R.id.btnWifi);

        iia = new ConnectionStatus(getApplicationContext());

        isConnected = iia.isConnectionAvailable();
        if (!isConnected) {
            btnWifi.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS));
                    Toast.makeText(getBaseContext(), "Please connect to a hotspot",
                            Toast.LENGTH_SHORT).show();
                }
            });
        }
        else {
            btnWifi.setVisibility(4);
            warning.setText("This app may use your mobile data to update events and get their details.");
        }
    }

在上面的代码中，如果结果为假，(因此没有互联网连接，用户将被带到Android wi-fi面板，在那里他将被提示连接到wi-fi热点。

我已经经历了所有的答案，我想出了我自己的答案，首先检查互联网是否可用，如果互联网可用，然后检查它是否活跃。

我已经包括了所有必要的方法和类来检查活跃的Internet连接。

NetworkUtils.class

public class NetworkUtils {

    public static final int STATUS_CONNECTED = 0 ;

    public static boolean isInternetAvailable(Context ctx){
        ConnectivityManager cm = (ConnectivityManager)ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
    }

    public static int isInternetActiveWithPing() {
        try {
            Runtime runtime = Runtime.getRuntime();
            Process process = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
            int exitValue = process.waitFor();
            return exitValue;
        } catch (Exception ex) {
            return -1;
        }
    }

    public static boolean isInternetActiveWithInetAddress() {
        try {
            InetAddress inetAddress = InetAddress.getByName("www.google.com");
            return inetAddress != null && !inetAddress.toString().equals("");
        } catch (Exception ex) {
            return false;
        }
    }

    public static void displayInternetConnectionMessage(Context ctx){
        Toast.makeText(ctx, "Check Internet Connection", Toast.LENGTH_SHORT).show();
    }
}

你可以使用下面的代码检查互联网是否活跃:

 private void checkInternetConnection() {
        if (NetworkUtils.isInternetAvailable(this)) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    if (NetworkUtils.isInternetActiveWithPing() == NetworkUtils.STATUS_CONNECTED) {
                        performNetworkingOperations();
                    } else {
                        if (NetworkUtils.isInternetActiveWithInetAddress()) {
                            performNetworkingOperations();
                        } else {
                            displayConnectionMessage();
                        }
                    }
                }
            }).start();

        } else {
            displayConnectionMessage();
        }
    }

    private void performNetworkingOperations() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(MainActivity.this, "Internet is Available", Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void displayConnectionMessage() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                NetworkUtils.displayInternetConnectionMessage(MainActivity.this);
            }
        });
    }

不需要太复杂。最简单的框架方式是使用ACCESS_NETWORK_STATE权限并创建一个连接的方法

public boolean isOnline() {
    ConnectivityManager cm =
        (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

    return cm.getActiveNetworkInfo() != null && 
       cm.getActiveNetworkInfo().isConnectedOrConnecting();
}

如果您有特定的主机和连接类型(wifi/移动)，也可以使用requestRouteToHost。

你还需要:

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

在你的android清单中。

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" />

The other answers that use ConnectivityManager are wrong because having a network connection doesn't mean you have internet access. For example, the user might be connected to a coffee shop's WiFi portal but can't get to the internet. To check that the internet is accessible you have to try to connect to an actual server. Normally when you want to do this you have a specific server in mind that you want to connect to, so go ahead and check if you can connect to that server. Here's a simple method for checking connectivity to a server.

private boolean isOnTheInternet() {
    try {
        URLConnection urlConnection = new URL("http://yourserver").openConnection();
        urlConnection.setConnectTimeout(400);
        urlConnection.connect();
        return true;
    } catch (Exception e) {
        return false;
    }
}

设置ConnectTimeout的原因是，否则它默认为TCP超时，可以有很多秒长。

还要注意的是，Android不允许你在主线程上运行这个程序。