android 判断网络是否断开

public class ConnectionChangeReceiver extends BroadcastReceiver 

{ 

  @Override 

  public void onReceive( Context context, Intent intent ) 

  { 

    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE ); 

    NetworkInfo activeNetInfo = connectivityManager.getActiveNetworkInfo(); 

    NetworkInfo mobNetInfo = connectivityManager.getNetworkInfo(     ConnectivityManager.TYPE_MOBILE ); 

    if ( activeNetInfo != null ) 

    { 

      Toast.makeText( context, "Active Network Type : " + activeNetInfo.getTypeName(), Toast.LENGTH_SHORT).show(); 

    } 

    if( mobNetInfo != null ) 

      Toast.makeText( context, "Mobile Network Type : " + mobNetInfo.getTypeName(), Toast.LENGTH_SHORT).show(); 

  } 

} 

<!-- Needed to check when the network connection changes --> 

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

<receiver android:name="com.blackboard.androidtest.receiver.ConnectionChangeReceiver" 

          android:label="NetworkConnection"> 

  <intent-filter> 

    <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/> 

  </intent-filter> 

</receiver>