在我目前所见过的所有方法中，最短、最干净的方法应该是:

public final static boolean isConnected( Context context )
{   
   final ConnectivityManager connectivityManager = 
         (ConnectivityManager) context.getSystemService( Context.CONNECTIVITY_SERVICE );  
   final NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();    
   return networkInfo != null && networkInfo.isConnected();
}

PS:这不会ping任何主机，它只是检查连接状态，所以如果你的路由器没有互联网连接，而你的设备连接到它，这个方法将返回true，尽管你没有互联网。 对于实际的测试，我建议执行一个HttpHead请求(例如到www.google.com)并检查状态，如果它是200 OK，一切正常，并且您的设备有互联网连接。

最好的方法:

public static boolean isOnline() {
    try {
    InetAddress.getByName("google.com").isReachable(3);

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

下面是一些现代代码，使用AsynTask来解决android崩溃的问题，当你尝试在主线程上连接并为用户引入一个带有冲洗和重复选项的警报。

class TestInternet extends AsyncTask<Void, Void, Boolean> {
    @Override
    protected Boolean doInBackground(Void... params) {
        try {
            URL url = new URL("http://www.google.com");
            HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
            urlc.setConnectTimeout(3000);
            urlc.connect();
            if (urlc.getResponseCode() == 200) {
                return true;
            }
        } catch (MalformedURLException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
            return false;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return false;
        }
        return false;
    }

    @Override
    protected void onPostExecute(Boolean result) {
        if (!result) { // code if not connected
            AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
            builder.setMessage("An internet connection is required.");
            builder.setCancelable(false);

            builder.setPositiveButton(
                    "TRY AGAIN",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                            new TestInternet().execute();
                        }
                    });


            AlertDialog alert11 = builder.create();
            alert11.show();
        } else { // code if connected
            doMyStuff();
        }
    }
}

...

new TestInternet().execute();

非常重要的是检查我们是否与isAvailable()有连接，以及是否可能与isConnected()建立连接

private static ConnectivityManager manager;

public static boolean isOnline(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.isAvailable() && networkInfo.isConnected();
}

你可以取消网络活动WiFi的类型:

public static boolean isConnectedWifi(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_WIFI;
}

或手机Móvil:

public static boolean isConnectedMobile(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_MOBILE;
}

不要忘记权限:

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

Kotlin和协程

我将函数放置在一个ViewModel中，该ViewModel具有viewModelScope。使用一个可观察的LiveData，我通知一个活动有关连接。

ViewModel

 fun checkInternetConnection(timeoutMs: Int) {
        viewModelScope.launch(Dispatchers.IO) {
            try {
                val socket = Socket()
                val socketAddress = InetSocketAddress("8.8.8.8", 53)

                socket.connect(socketAddress, timeoutMs)
                socket.close()

                _connection.postValue(true)
            }
            catch(ex: IOException) {
                _connection.postValue(false)
            }
        }
    }

 private val _connection = MutableLiveData<Boolean>()
 val connection: LiveData<Boolean> = _connection

活动

 private fun checkInternetConnection() {
     viewModel.connection.observe(this) { hasInternet ->
         if(!hasInternet) {
             //hasn't connection
         }
         else {
            //has connection
         }
     }
  }

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" />