Question

我正在尝试集成Spring + Hibernate4，但是当我访问我的DAO时，我在sessionFactory对象上得到了一个nullPointerException。

这是我的AbstractDao：

@Repository
public class AbstractDaoHibernateImpl {



    private SessionFactory sessionFactory;


    public AbstractDaoHibernateImpl() {

    }


    @Autowired
    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    public SessionFactory getSessionFactory() {
        return sessionFactory;
    }


    protected Session getSession() {
        return getSessionFactory().getCurrentSession();
    }

    protected Order getOrder(String orderBy, boolean isOrderAsc) {
        if (isOrderAsc)
            return Order.asc(orderBy);
        else
            return Order.desc(orderBy);
    }
}

这是我的实体bean配置：

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">

<beans>

    <!-- transacciones -->
    <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="SessionFactory"/>
    </bean>
    <!--Beans de los servicios de la aplicacion -->
    <bean id="userService" class="com.app.service.user.UserServiceImpl"/>

    <bean name="userDAO" class="com.app.model.user.dao.UserDaoImpl">
        <property name="sessionFactory" ref="SessionFactory" />
    </bean>

    <bean id="SessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation">
            <value>classpath:hibernate.cfg.xml</value>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${jdbc.dialect}</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>


</beans>

这是我的appContext的其余部分

<beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:aop="http://www.springframework.org/schema/aop"
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xmlns:security="http://www.springframework.org/schema/security"
        xmlns:mvc="http://www.springframework.org/schema/mvc"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:jee="http://www.springframework.org/schema/jee"

        xsi:schemaLocation="
            http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.springframework.org/schema/aop 
            http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context-3.0.xsd
            http://www.springframework.org/schema/tx 
            http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
            http://www.springframework.org/schema/security
            http://www.springframework.org/schema/security/spring-security-3.1.xsd
            http://www.springframework.org/schema/jee
            http://www.springframework.org/schema/jee/spring-jee-3.0.xsd">

    <context:component-scan base-package="com.app.controllers" />
        <mvc:annotation-driven />
    <context:annotation-config />

<tx:annotation-driven transaction-manager="transactionManager"/>
<import resource="applicationDatasource.xml" />

    <import resource="applicationEntityBean.xml" />


</beans>

最后这是我的服务对象：

@Service
public class UsuarioServiceImpl implements IUsuarioService {

    @Autowired
    private IUserDao userDao;

    public List<User> getUsers() throws GenericDataBaseException {
        return userDao.findAll();
    }


}

不应该像这样注入sessionFactory对象吗？

这是整个堆栈跟踪：

java.lang.NullPointerException
    at es.plexus.core.dao.impl.GenericDaoHibernateImpl.findAll(GenericDaoHibernateImpl.java:243)
    at es.plexus.service.usuario.UsuarioServiceImpl.getUsuarios(UsuarioServiceImpl.java:20)
    at es.plexus.controller.usuario.UsuarioController.listUsuarios(UsuarioController.java:24)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:722)

编辑：userDao：

public class UserDaoImpl extends GenericDaoHibernateImpl<Usuario, Long> implements IUserDao {


}

扩展了GenericDao：

public class GenericDaoHibernateImpl<E, PK extends Serializable> extends AbstractDaoHibernateImpl implements GenericDao<E, PK> {

private Class<E> entityClass;
    public GenericDaoHibernateImpl() {
        this.entityClass = (Class<E>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
    }

public List<E> findAll() throws GenericDataBaseException {
        try {
            Criteria criteria = getSession().createCriteria(getEntityClass());

            List<E> result = criteria.list();
            /*
             * if (result == null || result.size() == 0) throw new
             * NoSearchResultException("", getEntityClass().getName());
             */
            return result;
        } catch (Throwable t) {
            Collection<Object> args = new ArrayList<Object>();
            throw exceptionHandler.handle(this, t, "findAll", args);
        }
    }
    (...)
}

Answer 1

我看不到代码中任何地方都没有定义任何交易。

在这种情况下，我建议您将它们放在您的服务方法上：

@Transactional(readOnly = true)
public List<User> getUsers() throws GenericDataBaseException {
        return userDao.findAll();
    }

但您似乎正在开发一个相当复杂的类层次结构，您只需要一个通用存储库，然后instantiate that for different types。您不必使用服务类，仅在使用多个聚合根/复杂逻辑时推荐它们 - 而不是简单的getter。

Answer 2

让我猜一下。

您的DAO是否在com.app.controllers包裹下？如果没有像dao

那样将<context:component-scan base-package="com.app.controllers, com.app.model.user.dao" />包添加到组件扫描中

访问DAO时，sessionFactory为null

2 个答案: