IOException 无法解析主机，没有与主机名关联的地址

Question

我正在使用使用 WiFi.I 连接的 Sony Remote 相机工作，需要使用相机单击图片，然后将其上传到我的 FTP 服务器，该服务器位于另一个 activity.for比我需要断开我的相机 wifi 并连接到另一个 wifi 网络或移动设备 data.when 我连接到另一个 wifi/mobile 数据并将图片上传到 FTP 服务器我得到了这个错误.

IOException Unable to resolve host No address associated with hostname

当关闭应用程序并重新启动时，然后在没有 connecting/disconnection 相机的情况下直接上传图片，效果很好。有人，请告诉我如何解决这个问题，因为我检查了堆栈溢出的每个解决方案，但没有一个解决方案适合我。

我添加了以下权限

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_SETTINGS"/>

Answer 1

无法立即连接到网络。此外，如果所需的网络没有互联网连接，在 Android 的最新版本中它将不会连接（如果连接是由用户建立的，弹出窗口会显示连接确认）。

我使用 Android APIs 解决了这两个问题（2 个版本，一个用于 API<21，另一个用于 API>=21）。

试试这个代码（我正在使用 Android 注释来进行依赖注入，但这不是必需的）：

public class WifiHelper extends BroadcastReceiver {
    @RootContext
    Context context;

    @SystemService
    ConnectivityManager connectivityManager;

    @SystemService
    WifiManager wifiManager;

    // For API>=21
    private WifiHelperNetworkCallback wnc;

    // For API<21
    private boolean isBroadcastRegistered;

    private String desiredSSID;

    private Runnable callback;

    public void enableNetwork(String ssid, int networkId, Runnable callback) {
        desiredSSID = ssid;
        wifiManager.enableNetwork(networkId, true);
        configureNetworkRequest();
    }

    private void networkAvailable() {
        // this method will be called when the network is available
        callback.run();
    }

    private void configureNetworkRequest() {
        if (android.os.Build.VERSION.SDK_INT >= 21) {
            configureNetworkRequestAPI21();
        } else {
            configureNetworkRequestLegacy();
        }
    }

    @TargetApi(21)
    private void configureNetworkRequestAPI21() {
        NetworkRequest request = new NetworkRequest.Builder()
                .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
                .build();
        if (wnc == null) wnc = new WifiHelperNetworkCallback(this, connectivityManager);

        connectivityManager.requestNetwork(request, wnc);
    }

    private void configureNetworkRequestLegacy() {
        unregisterReceiver();

        connectivityManager.startUsingNetworkFeature(ConnectivityManager.TYPE_WIFI, null);
        IntentFilter intent = new IntentFilter();
        intent.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        intent.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);

        context.registerReceiver(this, intent);
        isBroadcastRegistered = true;
    }

    @TargetApi(21)
    private void disableNetworkRequest() {
        if (android.os.Build.VERSION.SDK_INT >= 21) {
            if (wnc != null) connectivityManager.unregisterNetworkCallback(wnc);

            ConnectivityManager.setProcessDefaultNetwork(null);
        } else {
            unregisterReceiver();
        }
    }

    private void unregisterReceiver() {
        if (isBroadcastRegistered) {
            context.unregisterReceiver(this);
            isBroadcastRegistered = false;
        }
    }

    // API<21
    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
            NetworkInfo networkInfo =
                    intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
            if(networkInfo.isConnected()) {
                // Wifi is connected

                if (desiredSSID.equals(getCurrentSSID())) {
                    // Callback and unregister
                    networkAvailable();
                    unregisterReceiver();
                }
            }
        }
    }

    public String getCurrentSSID() {
        WifiInfo wifiInfo = wifiManager.getConnectionInfo();
        if (wifiInfo != null && wifiInfo.getSupplicantState()== SupplicantState.COMPLETED) {
            return ssidWithoutQuotes(wifiInfo.getSSID());
        }
        else return null;
    }

    protected static String ssidWithoutQuotes(String ssid) {
        if (ssid == null) return null;
        else if (ssid.startsWith("\"") && ssid.endsWith("\"")) {
            return ssid.substring(1, ssid.length() - 1);
        } else {
            return ssid;
        }
    }

    protected String getDesiredSSID() {
        return desiredSSID;
    }

    @TargetApi(21)
    public static class WifiHelperNetworkCallback extends ConnectivityManager.NetworkCallback {
        public final String LOG_TAG = WifiHelper.class.getSimpleName();

        private ConnectivityManager connectivityManager;
        private WifiHelper wifiHelper;

        public WifiHelperNetworkCallback(WifiHelper wifiHelper, ConnectivityManager connectivityManager) {
            this.wifiHelper = wifiHelper;
            this.connectivityManager = connectivityManager;
        }

        public void onAvailable(Network network) {
            // Do something once the network is available
            NetworkInfo info = connectivityManager.getNetworkInfo(network);;

            Log.i(LOG_TAG, "networkcallback!! " + info.getExtraInfo());

            String desiredSSID = wifiHelper.getDesiredSSID();

            if (desiredSSID != null && desiredSSID.equals(ssidWithoutQuotes(info.getExtraInfo()))) {
                ConnectivityManager.setProcessDefaultNetwork(network);
                wifiHelper.networkAvailable();
            }
        }

    }

}

您将需要此权限：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.VIBRATE" android:maxSdkVersion="18"/>

IOException 无法解析主机，没有与主机名关联的地址

IOException Unable to resolve host,No address associated with hostname

java

ftp

android

sony

sony-camera-api