使用WifiManager你可以做到:

WifiManager wifi = (WifiManager) getSystemService (Context.WIFI_SERVICE);
if (wifi.getConnectionInfo().getNetworkId() != -1) {/* connected */}

方法getNeworkId只有在没有连接到网络时才返回-1;

我在我的应用程序中使用这个来检查活动网络是否为Wi-Fi:

ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo ni = cm.getActiveNetworkInfo();
if (ni != null && ni.getType() == ConnectivityManager.TYPE_WIFI)
{

    // Do your work here

}

许多答案使用了废弃的代码，或者在更高API版本上可用的代码。现在我用这样的东西

ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if(connectivityManager != null) {
            for (Network net : connectivityManager.getAllNetworks()) {
                NetworkCapabilities nc = connectivityManager.getNetworkCapabilities(net);
                if (nc != null && nc.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)
                        && nc.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET))
                    return true;
            }
        }
        return false;

这适用于最新版本的android:

fun getConnectionType(context: Context): ConnectivityType {
    var result = NONE
    val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (cm != null) {
            val capabilities = cm.getNetworkCapabilities(cm.activeNetwork)
            if (capabilities != null) {
                when {
                    capabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) -> {
                        result = WIFI
                    }
                    capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) -> {
                        result = MOBILE_DATA
                    }
                    capabilities.hasTransport(NetworkCapabilities.TRANSPORT_VPN) -> {
                        result = VPN
                    }
                }
            }
        }
    } else {
        if (cm != null) {
            val activeNetwork = cm.activeNetworkInfo
            if (activeNetwork != null) {
                // connected to the internet
                when (activeNetwork.type) {
                    ConnectivityManager.TYPE_WIFI -> {
                        result = WIFI
                    }
                    ConnectivityManager.TYPE_MOBILE -> {
                        result = MOBILE_DATA
                    }
                    ConnectivityManager.TYPE_VPN -> {
                        result = VPN
                    }
                }
            }
        }
    }
    return result
}

enum class ConnectivityType {
    NONE,
    MOBILE_DATA,
    WIFI,
    VPN,
}

在清单中:

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

我简单地使用以下方法:

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

它将在调用getSupplicantState()时返回这些状态之一;

ASSOCIATED - Association completed. ASSOCIATING - Trying to associate with an access point. COMPLETED - All authentication completed. DISCONNECTED - This state indicates that client is not associated, but is likely to start looking for an access point. DORMANT - An Android-added state that is reported when a client issues an explicit DISCONNECT command. FOUR_WAY_HANDSHAKE - WPA 4-Way Key Handshake in progress. GROUP_HANDSHAKE - WPA Group Key Handshake in progress. INACTIVE - Inactive state. INVALID - A pseudo-state that should normally never be seen. SCANNING - Scanning for a network. UNINITIALIZED - No connection.

这对我来说很管用:

    ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

    // Mobile
    State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();

    // Wi-Fi
    State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();

    // And then use it like this:

    if (mobile == NetworkInfo.State.CONNECTED || mobile == NetworkInfo.State.CONNECTING)
    {
        Toast.makeText(Wifi_Gprs.this,"Mobile is Enabled :) ....",Toast.LENGTH_LONG).show();
    }
    else if (wifi == NetworkInfo.State.CONNECTED || wifi == NetworkInfo.State.CONNECTING)
    {
        Toast.makeText(Wifi_Gprs.this,"Wifi is Enabled  :) ....",Toast.LENGTH_LONG).show();
    }
    else
    {
        Toast.makeText(Wifi_Gprs.this,"No Wifi or Gprs Enabled :( ....",Toast.LENGTH_LONG).show();
    }

并添加以下权限:

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