如何在应用程序启动之前和运行时检查互联网连接？

我找到了很多关于这个问题的答案，但也无法实现这些答案。 我想在这里实现这段代码，但无法做到。

这段代码是我在谷歌文档中找到的。

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

  NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
  boolean isConnected = activeNetwork != null &&
                  activeNetwork.isConnectedOrConnecting();   

https://developer.android.com/training/monitoring-device-state/connectivity-monitoring.html#DetermineConnection https://developer.android.com/training/monitoring-device-state/connectivity-monitoring.html#DetermineConnection

public class JSONfunctions {

public static JSONObject getJSONfromURL(String url) {
    InputStream is = null;
    String result = "";
    JSONObject jArray = null;

    // Download JSON data from URL
    try {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(url);
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();

    } catch (Exception e) {
        Log.e("log_tag", "Error in http connection " + e.toString());
    }

    // Convert response to string
    try {
        BufferedReader reader = null;
        if (is != null) {
            reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
        }
        StringBuilder sb = new StringBuilder();
        String line;
        if (reader != null) {
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
        }
        if (is != null) {
            is.close();
        }
        result = sb.toString();
    } catch (Exception e) {
        Log.e("log_tag", "Error converting result " + e.toString());
    }

    try {

        jArray = new JSONObject(result);
    } catch (JSONException e) {
        Log.e("log_tag", "Error parsing data " + e.toString());
    }

    return jArray;
}

}

UPDATE:

更新互联网检查的解决方案。现在对我有用的是这个

fun isNetworkAvailable(context: Context?): Boolean {
    if (context == null) return false

    val connectivityManager =
        context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
        val capabilities =
            connectivityManager.getNetworkCapabilities(connectivityManager.activeNetwork)
        return capabilities != null &&
                (capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) ||
                        capabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) ||
                        capabilities.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET))
    } else {
        try {
            val activeNetworkInfo = connectivityManager.activeNetworkInfo
            return activeNetworkInfo != null && activeNetworkInfo.isConnected
        } catch (ignored: Exception) {
        }
    }

    return false
}

OLD:

检查互联网连接的简单功能

protected boolean isOnline() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if (netInfo != null && netInfo.isConnected()) {
        return true;
    } else {
        return false;
    }
}

并且在您的 AndroidManifest.xml 中您应该添加权限

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