ネットワークの状態を調べる - コードを貼り付けながら。

このへんか。

NetworkInfoを使って、通信接続が可能状態か知る « Tech Booster

パーミッション

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

ソース

すこし手を入れながら理解する。

public class MainSample extends Activity implements OnClickListener {
    ConnectivityManager cm;
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        cm = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
        Button bt = (Button) findViewById(R.id.checkbutton);
        bt.setOnClickListener(this);
    }
 
    @Override
    public void onClick(View v) {
        NetworkInfo nInfo = cm.getActiveNetworkInfo();
        if (nInfo != null && nInfo.isConnected()) {
            appearToast(nInfo.getTypeName() + " Network connected");
        } else {
            appearToast("No Network Connection!");
        }
    }

    private void function appearToast(String message) {
        Toast.makeText(this, message, Toast.LENGTH_LONG).show();
    }

}

NetworkInfo | Android Developers

コードを探す。

how to see if wifi is connected in android - Stack Overflow

android.net.wifi.WifiManager m = (WifiManager) getSystemService(WIFI_SERVICE);
android.net.wifi.SupplicantState s = m.getConnectionInfo().getSupplicantState();
NetworkInfo.DetailedState state = WifiInfo.getDetailedStateOf(s);
if( state != NetworkInfo.DetailedState.CONNECTED ){
    return false;
}

ConnectivityManager connManager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
NetworkInfo mWifi = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

if (mWifi.isConnected()) {
    // Do whatever
}

Wi-Fiの状態は細かく取れる。

SupplicantState supState; 
wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
WifiInfo wifiInfo = wifiManager.getConnectionInfo();
supState = wifiInfo.getSupplicantState();

AUTHENTICATING	Network link established, performing authentication.
BLOCKED	Access to this network is blocked.
CONNECTED	IP traffic should be available.
CONNECTING	Currently setting up data connection.
DISCONNECTED	IP traffic not available.
DISCONNECTING	Currently tearing down data connection.
FAILED	Attempt to connect failed.
IDLE	Ready to start data connection setup.
OBTAINING_IPADDR	Awaiting response from DHCP server in order to assign IP address information.
SCANNING	Searching for an available access point.
SUSPENDED	IP traffic is suspended

「Androidが通信可能かどうか」を取りたいので、

        cm = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);

        NetworkInfo nInfo = cm.getActiveNetworkInfo();
        if (nInfo != null && nInfo.isConnected()) {
            appearToast(nInfo.getTypeName() + " Network connected");
        } else {

結局ここらか。

ConnectivityManager

このクラスでネットワーク周りを操作。

ConnectivityManager | Android Developers