使用BroadCastreceiver和服务打开设备wi-Fi时如何显示Toast？

我想制作不应扩展任何Activity类的应用程序。

当我打开设备的Wi-Fi时，我的应用程序必须在后台运行并显示Toast。我的NetworkUtil代码在这里

public class NetworkUtil {

public static int TYPE_WIFI = 1;
public static int TYPE_MOBILE = 2;
public static int TYPE_NOT_CONNECTED = 0;


public static int getConnectivityStatus(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    if (null != activeNetwork) {
        if(activeNetwork.getType() == ConnectivityManager.TYPE_WIFI)
            return TYPE_WIFI;

        if(activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE)
            return TYPE_MOBILE;
    } 
    return TYPE_NOT_CONNECTED;
}

public static String getConnectivityStatusString(Context context) {
    int conn = NetworkUtil.getConnectivityStatus(context);
    String status = null;
    if (conn == NetworkUtil.TYPE_WIFI) {
        status = "Wifi enabled";
    } else if (conn == NetworkUtil.TYPE_MOBILE) {
        status = "Mobile data enabled";
    } else if (conn == NetworkUtil.TYPE_NOT_CONNECTED) {
        status = "Not connected to Internet";
    }
    return status;
}

}

接收器类在这里。请帮我展示吐司。

public class NetworkChangeReceiver extends BroadcastReceiver {

@Override
public void onReceive(final Context context, final Intent intent) {

    String status = NetworkUtil.getConnectivityStatusString(context);

    Toast.makeText(context, status, Toast.LENGTH_LONG).show();
}

}

**我的清单是**

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="net.viralpatel.network"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="15"
    android:targetSdkVersion="23" />

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

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <receiver
        android:name="net.viralpatel.network.NetworkChangeReceiver"
        android:label="NetworkChangeReceiver" >
        <intent-filter>
            <action android:name="android.net.wifi.WIFI_STATE_CHANGED"/>
            <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
        </intent-filter>
    </receiver>
</application>