排序操作

public synchronized void sort(File file, int displayOrder, int parentId){
        int max = count(parentId);
        if(displayOrder > max){
            displayOrder = max;
        }
        
        if(file.getDisplayOrder() > displayOrder){
            fileDao.batchExecute("update File set displayOrder = displayOrder + 1 where parentId = ? and displayOrder >=? and displayOrder < ?", parentId, displayOrder, file.getDisplayOrder());
        }
        else{
            fileDao.batchExecute("update File set displayOrder = displayOrder - 1 where parentId = ? and displayOrder >? and displayOrder <= ?", parentId, file.getDisplayOrder(), displayOrder);
        }
        file.setDisplayOrder(displayOrder);
        save(file);
    }