...
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission> 
<uses-permission android:name="android.permission.INTERNET">            </uses-permission>
...
    <receiver android:name=".Internet" android:enabled="true"> 
        <intent-filter> 
            <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
        </intent-filter> 
    </receiver> 
...

接收器：

package YourPackage;
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
 
    public class Internet extends BroadcastReceiver
    {    
        @Override
        public void onReceive(final Context context,Intent intent) 
        {   
            if (intent.getAction().equalsIgnoreCase("android.net.conn.CONNECTIVITY_CHANGE"))
            {
                if isInternet(context)
                { 
                    // Your Code
                }
            }       
        }
 
        public boolean isInternet(Context context) 
        {
            ConnectivityManager IM = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeNetworkInfo = IM.getActiveNetworkInfo();
            return activeNetworkInfo != null;
        }     
    }