java - 在 Android 中获取网络连接警告

Question

我正在尝试以编程方式检测，当 Android 手机触发此“警告”时，已建立的互联网连接当前似乎无法访问(在这种情况下:Edge/2G)，如下所示:

事实上，当这个警告出现时，互联网就无法访问，没有它，它就可以工作。
我目前正在做的是检测正确的网络:

public String getNetworkClass() {

    if (ActivityCompat.checkSelfPermission(context, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
        return "Unknown";
    } else {
        int networkType = mTelephonyManager.getNetworkType();
        Log.i("NETWORK", String.valueOf(networkType));
        mobileNetworkType = networkType;

        switch (networkType) {
            case TelephonyManager.NETWORK_TYPE_GPRS:
            case TelephonyManager.NETWORK_TYPE_EDGE:
            case TelephonyManager.NETWORK_TYPE_CDMA:
            case TelephonyManager.NETWORK_TYPE_1xRTT:
            case TelephonyManager.NETWORK_TYPE_IDEN:
                return "2G";
            case TelephonyManager.NETWORK_TYPE_UMTS:
            case TelephonyManager.NETWORK_TYPE_EVDO_0:
            case TelephonyManager.NETWORK_TYPE_EVDO_A:
            case TelephonyManager.NETWORK_TYPE_HSDPA:
            case TelephonyManager.NETWORK_TYPE_HSUPA:
            case TelephonyManager.NETWORK_TYPE_HSPA:
            case TelephonyManager.NETWORK_TYPE_EVDO_B:
            case TelephonyManager.NETWORK_TYPE_EHRPD:
            case TelephonyManager.NETWORK_TYPE_HSPAP:
                return "3G";
            case TelephonyManager.NETWORK_TYPE_LTE:
                return "4G";
            case TelephonyManager.NETWORK_TYPE_NR:
                return "5G";
            default:
                return "Unknown";
        }
    }
}

当它是 2G 时，我正在测量下载/上传速率。我为自己定位 here猜测低于 150 kbps 的下载速率可能会导致“警告”:

if(Arrays.asList(new String[]{"2G"}).contains(getNetworkClass())) {
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkCapabilities nc = cm.getNetworkCapabilities(cm.getActiveNetwork());
    int downSpeed = nc.getLinkDownstreamBandwidthKbps();
    int upSpeed = nc.getLinkUpstreamBandwidthKbps();
    

    if(downSpeed < 150) {
        // I assume the connection is bad here                            
    } else {
        // All fine!
    }

但是，我的测量值在 30 到 100 kbps(每五秒一次)之间，有时在此范围内会出现警告，有时不会出现。
我怎样才能成功捕捉到这个？是否有任何Android界面来检查这个？如果可能的话，我想 避免 ping 检查，例如:

public boolean canAccessInternet() {
    Runtime runtime = Runtime.getRuntime();
    try {
        Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
        int exitValue = ipProcess.waitFor();
        System.out.println("Network mExitValue " + exitValue);
        return (exitValue == 0);
    } catch (IOException e) {
        System.out.println(" IO Error ");
        e.printStackTrace();
    } catch (InterruptedException e) {
        System.out.println(" Interrupted Error ");
        e.printStackTrace();
    }
    return false;
}

Answer 1

AFAIK，您在连接图标上显示的感叹号引用的 UX 由网络功能驱动 NET_CAPABILITY_VALIDATED (link)。

Indicates that connectivity on this network was successfullyvalidated. For example, for a network with NET_CAPABILITY_INTERNET, itmeans that Internet connectivity was successfully detected.

因此，在您的代码中，您将其更新为:

...
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(
    Context.CONNECTIVITY_SERVICE);
NetworkCapabilities nc = cm.getNetworkCapabilities(cm.getActiveNetwork());
if(!nc.hasCapability(NET_CAPABILITY_VALIDATED)) {
    // Show the exclamation point
}