我向用户显示了启用gps设置的提示,但是如何检查用户是否真的启用了手机上的gps位置？

@H_301_6@private static void showGPSDisabledAlertToUser() {
        // TODO Auto-generated method stub
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(ChatSDK.getSDKInstance().activity);
        alertDialogBuilder
                .setMessage(
                        "GPS is disabled in your device. Would you like to enable it?")
                .setCancelable(false)
                .setPositiveButton("Goto Settings Page To Enable GPS",new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog,int id) {
                                Intent callGPSSettingIntent = new Intent(
                                        android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                                ChatSDK.getSDKInstance().activity.startActivity(callGPSSettingIntent);
                            }
                        });
//      alertDialogBuilder.setNegativeButton("Cancel",//              new DialogInterface.OnClickListener() {
//                  public void onClick(DialogInterface dialog,int id) {
//                      dialog.cancel();
//                  }
//              });
        AlertDialog alert = alertDialogBuilder.create();
        alert.show();
    }
}