Spring 3：@Autowired dao 字段在带有 @Transactional 注释的服务 bean 中为空答案

【问题标题】：Spring 3 : @Autowired dao fields are null in service beans with @Transactional annotationSpring 3：@Autowired dao 字段在带有 @Transactional 注释的服务 bean 中为空
【发布时间】：2014-01-16 06:45:24
【问题描述】：

我对接口的编码如下：

DAO 接口：

public interface SampleTblDao extends BaseDao<SampleTbl> {

/**
* 
* @param mapper
* @param sampleKey
* @return
* @throws DataAccessException
*/
public SampleTbl selectSampleTbl(SampleKey sampleKey) throws DataAccessException;

}

DAO 实现

public class SampleTblDaoImpl extends AbstractBaseDao<SampleTbl, SampleTblMapper> implements SampleTblDao {

  public SampleTblDaoImpl() {
    super(SampleTblMapper.class);
  }

  @Override
  public SampleTbl selectSampleTbl(SampleKey sampleKey) throws DataAccessException {
    return getSqlSession().getMapper(SampleTblMapper.class).selectSampleTbl(sampleKey);
  }

}

业务逻辑接口：

public interface SampleBusinessLogic {

  /**
   * 
   * @param sample
   * @return
   * @throws SampleException
   */
  public Sample createSample(Sample sample) throws SampleException;

  /**
   * 
   * @param sample
   * @return
   * @throws SampleException
   */
   public Sample updateSample(Sample sample) throws SampleException;

  /**
   * @param sampleKey
   * @return
   * @throws SampleException
   */
   public Sample getSample(SampleKey sampleKey) throws SampleException;

   }

业务逻辑实现：

 public class SampleBusinessLogicImpl implements SampleBusinessLogic {

    /**
     * sample table dao
     */
    @Autowired
    @Qualifier(value = "sampleTblDao")
    private SampleTblDao sampleTblDao;

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Sample createSample(Sample sample) throws SampleException {

        try {
            // sample table
            createSampleTbl(sample.getSampleTbl());

        } catch (Exception e) {

            List < String > messageList = new ArrayList < String > ();
            String message = "{createSample : " + "{itemId=" + sample.getSampleTbl().getItemId() + "}," + "{itemName=" + sample.getSampleTbl().getItemName() + "}}";

            messageList.add("createShop system error");

            throw new SampleException(message, messageList, e);

        }

        return sample;
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Sample updateSample(Sample sample) throws SampleException {

        List < String > messageList = null;
        String message = null;

        try {

            // global shop table
            updateSampleTbl(sample.getSampleTbl());

        } catch (IllegalDataException e) {

            message = "{updateSample : " + "{itemId=" + sample.getSampleTbl().getItemId() + "}," + "{itemName=" + sample.getSampleTbl().getItemName() + "}}";

            messageList = new ArrayList < String > ();
            messageList.add("updateSample illegal data error");

            throw new SampleException(message, messageList, e);

        } catch (Exception e) {

            message = "{updateSample : " + "{itemId=" + sample.getSampleTbl().getItemId() + "}," + "{itemName=" + sample.getSampleTbl().getItemName() + "}}";

            messageList = new ArrayList < String > ();
            messageList.add("updateSample system error");

            throw new SampleException(message, messageList, e);

        }

        return sample;

    }

    @Override
    @Transactional(rollbackFor = Exception.class, readOnly = true)
    public Sample getSample(SampleKey sampleKey) throws SampleException {

        Sample sample = new Sample();

        String message = null;
        List < String > messageList = null;

        try {

            sample.setSampleTbl(getSampleTbl(sampleKey));

        } catch (DataNotFoundException e) {

            message = "{getSample : " + "{itemId=" + sampleKey.getItemId() + "}}";

            messageList = new ArrayList < String > ();
            messageList.add("getSample data not found error");

            throw new SampleException(message, messageList, e);

        } catch (Exception e) {

            message = "{getSample : " + "{itemId=" + sampleKey.getItemId() + "}}";

            messageList = new ArrayList < String > ();
            messageList.add("getSample system error");

            throw new SampleException(message, messageList, e);

        }

        return sample;
    }

    /**
     *
     * @param sampleTbl
     * @throws Exception
     */
    private void createSampleTbl(SampleTbl sampleTbl) throws Exception {

        sampleTbl.setItemId(new UUID().toString());
        sampleTblDao.insert(sampleTbl);
    }

    /**
     * @param sampleTbl
     * @throws Exception
     */
    private void updateSampleTbl(SampleTbl sampleTbl) throws Exception {

        if (sampleTbl.isTransactionTarget(SampleTbl.class)) {

            String message = null;
            SampleKey sampleKey = new SampleKey();
            sampleKey.setItemId(sampleTbl.getItemId());

            SampleTbl sampleTblPre = sampleTblDao.selectSampleTbl(sampleKey);

            if (sampleTblPre == null) {
                // if sample table is empty
                message = "{illegal data error:{sampleTblPre=null}}";
                throw new IllegalDataException(message);
            }

            sampleTbl.setItemId(sampleTblPre.getItemId());
            sampleTblDao.update(sampleTbl);

        }

    }

    /**
     * @param sampleKey
     * @return
     * @throws Exception
     */
    private SampleTbl getSampleTbl(SampleKey sampleKey) throws Exception {

        String message = "";

        SampleTbl sampleTbl = sampleTblDao.selectSampleTbl(sampleKey);

        if (sampleTbl == null) {
            // if sample tbl is empty
            message = "{data not found error:{SampleTbl=null}}";
            throw new DataNotFoundException(message);
        }

        return sampleTbl;
    }

    public void setSampleTblDao(SampleTblDao sampleTblDao) {
        this.sampleTblDao = sampleTblDao;
    }
}

在应用程序上下文 XML 中，我将 bean 配置如下：

<bean id="sampleTblDao" class="com.rakuten.gep.sample.dao.impl.SampleTblDaoImpl" parent="baseDAO" scope="singleton">
        <property name="namespace" value="com.rakuten.gep.sample.dao.mapper.SampleTblMapper" />
</bean>
<bean id="sampleBusinessLogic" class="com.rakuten.gep.sample.businesslogic.impl.SampleBusinessLogicImpl" scope="singleton"/>

<!-- and annocation based transaction is configured as follows -->
<tx:annotation-driven transaction-manager="trx-manager" proxy-target-class="true" />

<bean id="trx-manager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
       <property name="dataSource" ref="dataSource"/>
</bean>

但经过调试，我发现'SampleBusinessLogicImpl'中的自动连接字段'sampleTblDao'总是为空。

有什么建议吗？

【问题讨论】：

使用时如何获取SampleBusinessLogicImpl 实例？另外，您的注释语法很奇怪
我在 Jersery Resources 中使用它们。我使用 @AutoWire 注释很好地注入它们。
我在您的配置中没有看到 <context:annotation-config /> 或 <context:compoment-scan />。基本上无视@Autowired。
@M.Deinum 谢谢这是问题。你能把这个答案发给我可以接受吗

标签： java spring spring-aop spring-transactions

【解决方案1】：

您正在使用 XML 配置内容并（部分）依赖注释。默认情况下，spring 会忽略所有注释，如 @Autowired、@Inject 等。要启用这些注释的处理，需要注册AutowiredAnnotationBeanPostProcessor 和CommonAnnotationBeanPostProcessor 的实例（后者用于@Resource 和其他JSR-250 注释处理）。

这可以手动完成，也可以使用命名空间来完成。

<context:annotation-config />

当使用<context:component-scan /> 时，已经暗示要使用注释进行配置，因此<context:annotation-config /> 的功能已经包含，因此无需再次添加。

【讨论】：