android 检查网络

 public static boolean isNetworkConnected(Context context) {
	ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
	NetworkInfo network = cm.getActiveNetworkInfo();

	if (network != null) {
	    return network.isAvailable();
	}

	return false;
    }

   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/><!-- 检查网络 -->