判断网络是否可用

/** * 判断当前网络是否可用 * */public boolean judgeNetAvailable(){    ConnectivityManager manager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);               NetworkInfo networkinfo = manager.getActiveNetworkInfo();                 if (networkinfo == null || !networkinfo.isAvailable()) //网络不可用的情况        {        return false;        }        else        {        return true;        }        }startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入网络配置界面（鲁大）?<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>