Question

我们正在开发Tapestry5-Spring-Hibernate应用程序我们使用的是Tapestry 5.4.1，Spring 4.3.1.RELEASE和Hibernate 4.3.6.Final 我们正在使用基于XML的应用程序我们面临的问题是@Autowired到spring服务中的所有daos总是为null。每当需要dao来对数据库执行操作时，这当然会生成NullpointerException 我们使用通用服务和dao接口
以下是代码示例：
Spring配置文件

<context:annotation-config />
    <context:component-scan base-package="org.prism.forecast" />

    <context:property-placeholder location="classpath:hibernate.properties" />
 <!--Generic DAO -->
    <bean id="appDao" primary="true" class="org.prism.forecast.dao.AppDaoImpl">
        <property name="sessionFactory">
            <ref bean="sessionFactory" />
        </property>
    </bean>
    <!--Generic service-->
    <bean id="appServiceImpl" class="org.prism.forecast.services.AppServiceImpl">
        <property name="dao">
            <ref bean="appDao" />
        </property>
    </bean>

    <bean id="requestDao" class="org.prism.forecast.dao.RequestDaoImpl">
        <property name="sessionFactory">
            <ref bean="sessionFactory" />
        </property>
    </bean>

    <bean id="requestServiceImpl" class="org.prism.forecast.services.RequestServiceImpl">
        <property name="dao">
            <ref bean="requestDao" />
        </property>
    </bean>

     <bean id="SOPUploadDao" class="org.prism.forecast.dao.SOPUploadDaoImpl">
        <property name="sessionFactory">
            <ref bean="sessionFactory" />
        </property>
    </bean>

    <bean id="SOPUploadServiceImpl" class="org.prism.forecast.services.SOPUploadServiceImpl">
        <property name="dao">
            <ref bean="SOPUploadDao" />
        </property>
    </bean>

   <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
      <property name="dataSource" ref="dataSource" />
      <property name="packagesToScan" value="org.prism.forecast.entities" />
      <property name="hibernateProperties">
         <props>
            <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>
            <prop key="hibernate.dialect">${hibernate.dialect}</prop>
         </props>
      </property>
   </bean>

   <bean id="dataSource" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource">
      <property name="driverClassName" value="${jdbc.driverClassName}" />
      <property name="url" value="${jdbc.url}" />
      <property name="username" value="${jdbc.username}" />
      <property name="password" value="${jdbc.password}" />
   </bean>

   <bean id="txManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
      <property name="sessionFactory" ref="sessionFactory" />
   </bean>

    <bean id="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate">
        <property name="transactionManager" ref="txManager"/>
    </bean>

   <tx:annotation-driven transaction-manager="txManager" />

   <bean id="persistenceExceptionTranslationPostProcessor"
    class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>

通用DAO接口

public interface AppDao {

    /**
     * Finds an object by id
     * 
     * @param <T>
     * @param <PK>
     * @param type
     * @param id
     * @return the object
     */
    <T, PK extends Serializable> T find(Class<T> type, PK id);
//other methods
}

通用DAO实施

@Repository("appDao")
public class AppDaoImpl implements AppDao {

    protected static final Logger logger = LoggerFactory.getLogger(RequestDaoImpl.class);

    @Inject
    protected Session session;

    @Resource(name = "sessionFactory")
    protected SessionFactory sessionFactory;


    /**
     * @param sessionFactory the sessionFactory to set
     */
    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    @SuppressWarnings("unchecked")
    public <T, PK extends Serializable> T find(Class<T> type, PK id) {
        return (T) session.get(type, id);
    }
//other methods
}

请求DAO

public interface RequestDao extends AppDao {
}

请求DAO实施

@Repository("requestDao")
public class RequestDaoImpl extends AppDaoImpl implements RequestDao {
}

通用服务

public interface AppService {

    /**
     * @param <T>
     * @param <PK>
     * @param type
     * @param id
     * @return the object
     */
    <T, PK extends Serializable> T find(Class<T> type, PK id);
//Other methods
}

通用服务实施

@Service("appService")
@Transactional(propagation = Propagation.REQUIRED, readOnly = true)
public class AppServiceImpl implements AppService {

    @Autowired
    private AppDao dao = null;

    /**
     * @return the dao
     */
    public AppDao getDao() {
        return dao;
    }

    /**
     * @param dao
     *            the dao to set
     */
    public void setDao(AppDao dao) {
        this.dao = dao;
    }

    @Override
    public <T, PK extends Serializable> T find(Class<T> type, PK id) {
        return dao.find(type, id);//dao is null here
    }
//other methods
}

请求服务

public interface RequestService extends AppService {
}

请求服务实施

@Service("requestService")
@Transactional(propagation = Propagation.REQUIRED, readOnly = true)
public class RequestServiceImpl extends AppServiceImpl implements RequestService {

    @Autowired
    private RequestDao dao;

    @Override
    public Request find(Request request) {
        dao.find(request);
    }
//other methods
}

Tapestry页面中的用法

public class ManageRequest{

    //dao needed for persistence operations
    @InjectService("requestService")
    protected requestService service;
}

在调试应用程序时，我们发现服务已正确注入页面，但dao尚未注入服务。谁能告诉我这里出了什么问题？

Answer 1

这看起来像Spring配置问题，可能需要在<context:component-scan ... />中明确指定DAO服务的子包，即：

<context:component-scan base-package="org.prism.forecast, org.prism.forecast.dao" />

一些提示：@Autowired service is null和multiple packages in context:component-scan。

Tapestry-Spring Autowired dao在服务中始终为空

1 个答案: