Android AlertDialog 获取PositiveButton的控制权

final AlertDialog.Builder alert = new AlertDialog.Builder(
                         CloudSyncActivity.this);
                 alert.setIcon(getResources().getDrawable(R.drawable.about));
                 alert.setTitle("标题");
                 alert.setMessage("输入提示信息");
                 alert.setPositiveButton("确认",
                         new DialogInterface.OnClickListener() {

                             @Override
                             public void onClick(DialogInterface dialog,
                                     int which) {                                //控制点击按钮不消失问题
                                 try
                                 {
                                 Field field = dialog.getClass()
                                 .getSuperclass().getDeclaredField(
                                 "mShowing" );
                                 field.setAccessible( true );
                                 // 将mShowing变量设为false，表示对话框已关闭
                                 field.set(dialog, false );
                                 dialog.dismiss();

                                 }
                                 catch (Exception e)
                                 {

                                 }
                             //获取按钮对象
                             Button PositiveButton=((AlertDialog)dialog).getButton(AlertDialog.BUTTON_POSITIVE);
                            //对按钮进行操作
                             PositiveButton.setVisibility(View.GONE);
                       
                             }
                         });
                 alert.setNegativeButton("取消",
                         new DialogInterface.OnClickListener() {

                             @Override
                             public void onClick(DialogInterface dialog,
                                     int which) {
                                 try
                                 {
                                 Field field = dialog.getClass()
                                 .getSuperclass().getDeclaredField(
                                 "mShowing" );
                                 field.setAccessible( true );
                                 // 将mShowing变量设为false，表示对话框已关闭
                                 field.set(dialog, true );
                                 dialog.dismiss();

                                 }
                                 catch (Exception e)
                                 {

                                 }
                             }
                         });
                 alert.show();