判断网络是否有效

protected boolean isInternetAvailable(Context ctx) {try {ConnectivityManager cm = (ConnectivityManager) ctx.getSystemService(Context.CONNECTIVITY_SERVICE);return ((cm.getActiveNetworkInfo() != null)&& (cm.getActiveNetworkInfo().isAvailable())&& (cm.getActiveNetworkInfo().isConnected()));} catch (Exception e) {e.printStackTrace()}return false;}

需要添加permission

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

其实还可以通过Network Information获得连接类型等信息