java - 如果数据存在或如果数据不存在如何检索单行 - hibernate

Question

这是我在 java 中的实现，如果数据存在则检索单行，如果不存在数据则检索 null 或空。

public SalesForecast isSalesForecastUser(String mobile) throws LookupException {
        SalesForecast salesForecast = null;
        Session session = null;
        try {
            session = hibernateTemplate.getSessionFactory().openSession();
            salesForecast = (SalesForecast) session.createQuery(" from SalesForecast salesforcast where salesforcast.ppUserMobile ='" + mobile + "' ").list().get(0);
        } catch (NullPointerException n) {
            n.printStackTrace();
        } catch (IndexOutOfBoundsException n) {
            n.printStackTrace();
        } finally {
            session.close();
        }

        return salesForecast;
    }

如果有单行或多行，这工作正常，但当没有匹配的行时抛出此异常:

java.lang.IndexOutOfBoundsException: Index: 0, Size: 0

Answer 1

你可以这样试试

    Query query = session.createQuery(" from SalesForecast salesforcast where
                                  salesforcast.ppUserMobile ='" + mobile + "' ");
    List results = query.list();
    if(results!=null){
        return results.get(0);
    } else{
        return null;
    }

在你当前的代码中

 salesForecast = (SalesForecast) session.createQuery(" from SalesForecast 
 salesforcast where salesforcast.ppUserMobile ='" + mobile + "' ").list() 
 // list will null if no result there, So you will get NullPoiterException