Question

我将Hibernate4，Spring3和JSF2用于小型应用程序，将Weblogic 10.3.6用作Apps服务器。

为了启用JPA2，我在commEnv.cmd

中添加了以下内容

@rem Enable JPA 2.0 functionality on WebLogic Server
set PRE_CLASSPATH=%BEA_HOME%\modules\javax.persistence_1.1.0.0_2-0.jar;
%BEA_HOME%\modules\com.oracle.jpa2support_1.0.0.0_2-1.jar

当我运行我的应用程序时，我在以下行获取空指针异常。我该如何解决这个问题？

CriteriaBuilder cb = entityManager.getCriteriaBuilder();

我的DAO

@Named
public class RequestDAOImpl implements RequestDAO {

protected EntityManager entityManager;

public void getRequest(RequestQueryData data){
        Map<String, String> filters = data.getFilters();
        int start = data.getStart();
        int end = data.getEnd();
        String sortField = data.getSortField();
        QuerySortOrder order = data.getOrder();

        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
        CriteriaQuery<Request> c = cb.createQuery(Request.class);
        Root<Request> emp = c.from(Request.class);
        c.select(emp);
                ...... other code

的applicationContext.xml

<bean class="org.springframework.beans.factory.config.CustomScopeConfigurer">
        <property name="scopes">
            <map>
                <entry key="view">
                    <bean class="org.primefaces.spring.scope.ViewScope" />
                </entry>
            </map>
        </property>
    </bean>
    <context:component-scan base-package="net.test" />
    <!-- Data Source Declaration -->
    <bean id="DataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
        destroy-method="close">
        <property name="driverClass" value="oracle.jdbc" />
        <property name="jdbcUrl"
            value="jdbc:oracle:thin:@server:1521:ORCL" />
        <property name="user" value="scott" />
        <property name="password" value="tiger" />
        <property name="maxPoolSize" value="10" />
        <property name="maxStatements" value="0" />
        <property name="minPoolSize" value="5" />
    </bean>     
    <!-- Session Factory Declaration -->
    <bean id="SessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="DataSource" />
        <property name="annotatedClasses">
            <list>
                <value>net.test.model.Request</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.query.factory_class">org.hibernate.hql.internal.classic.ClassicQueryTranslatorFactory
                </prop>
            </props>
        </property>
    </bean>
    <!-- Enable the configuration of transactional behavior based on annotations -->
    <tx:annotation-driven transaction-manager="txManager" />
    <!-- Transaction Manager is defined -->
    <bean id="txManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="SessionFactory" />
    </bean>

更新1

的applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-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/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <!-- Spring view scope customized -->

    <bean class="org.springframework.beans.factory.config.CustomScopeConfigurer">
        <property name="scopes">
            <map>
                <entry key="view">
                    <bean class="org.primefaces.spring.scope.ViewScope" />
                </entry>
            </map>
        </property>
    </bean>
    <context:component-scan base-package="net.test" />
    <!-- Data Source Declaration -->
    <bean id="DataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
        destroy-method="close">
        <property name="driverClass" value="oracle.jdbc" />
        <property name="jdbcUrl"
            value="jdbc:oracle:thin:@server:1521:ORCL" />
        <property name="user" value="scott" />
        <property name="password" value="tiger" />
        <property name="maxPoolSize" value="10" />
        <property name="maxStatements" value="0" />
        <property name="minPoolSize" value="5" />
    </bean>
      <bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>
    <!-- JPA Entity Manager Factory -->
    <bean id="entityManagerFactory" 
          class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> 
         <property name="dataSource" ref="DataSource" />
         <property name="packagesToScan" value="net.test.model" />
         <property name="jpaVendorAdapter">
      <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">  
       </bean>
   </property>         
      </bean> 
      <bean id="defaultLobHandler" class="org.springframework.jdbc.support.lob.DefaultLobHandler" />        
    <!-- Session Factory Declaration -->
    <bean id="SessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="DataSource" />
        <property name="annotatedClasses">
            <list>
                <value>net.test.model.Request</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.query.factory_class">org.hibernate.hql.internal.classic.ClassicQueryTranslatorFactory
                </prop>
            </props>
        </property>
    </bean>
    <!-- Enable the configuration of transactional behavior based on annotations 
    <tx:annotation-driven transaction-manager="txManager" />-->
    <!-- Transaction Manager is defined 
    <bean id="txManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="SessionFactory" />
    </bean>-->

     <!-- Transaction Config -->
    <bean id="transactionManager"
          class="org.springframework.orm.jpa.JpaTransactionManager">
          <property name="entityManagerFactory" ref="entityManagerFactory" />
          </bean>   

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

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

     <context:annotation-config/>


    <bean id="hibernateStatisticsMBean" class="org.hibernate.jmx.StatisticsService">
        <property name="statisticsEnabled" value="true" />
        <property name="sessionFactory" value="#{entityManagerFactory.sessionFactory}" />
    </bean>
    <bean name="ehCacheManagerMBean"
        class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" />

    <bean id="mbeanServer" class="org.springframework.jmx.support.MBeanServerFactoryBean">
        <property name="locateExistingServerIfPossible" value="true" />
    </bean>

    <bean id="jmxExporter" class="org.springframework.jmx.export.MBeanExporter" lazy-init="false">
        <property name="server" ref="mbeanServer" />
        <property name="registrationBehaviorName" value="REGISTRATION_REPLACE_EXISTING"/>
        <property name="beans">
            <map>               
                <entry key="SpringBeans:name=hibernateStatisticsMBean" value-ref="hibernateStatisticsMBean" />
                <entry key="SpringBeans:name=ehCacheManagerMBean" value-ref="ehCacheManagerMBean" />
            </map>
        </property>
    </bean>

</beans>

Answer 1

您的EntityManager似乎没有连接到您的DAO。在XML中添加@Autowired，@PersistenceContext或ref。请注意，要仅使用@Autowired，您必须将EntityManager指定为bean。

另一种可能性：如果您的DAO也未被指定为bean（在XML中或使用各种@Component注释之一（可能是@Repository），Spring将不知道要连线事情，或者。

更新：这里有几种不同的解决方案。不过，在此之前，确保你有

    <mvc:annotation-driven />

在您的一个XML中。这将启用弹簧注释，并为编辑XML节省很多麻烦。请注意，您还需要更新<beans>代码中的xmlns和schemaLocation。

xmlns:mvc="http://www.springframework.org/schema/mvc"

和

   http://www.springframework.org/schema/mvc
   http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd

schemaLocation中的

。

看起来您现在正在指定EntityManagerFactory。这是一个好的开始。您现在也可以指定EntityManager。

<bean id="entityManager" class="org.springframework.orm.jpa.support.SharedEntityManagerBean">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
</bean>

但我无法保证您的XML和EntityManagerFactory设置。你似乎在不知名的地方漂浮着</property>。

我不确定你是如何访问你的DAO的。如果它已经是一个bean并且在组件扫描中，那么你就是好的。如果没有，请确保使用@Repository注释您的DAO类，并确保其包在组件扫描范围内。当然，如果你还没有将它指定为bean，这意味着你可能在其他地方实例化它 - 这绝对不是你想要如何使用你的DAO。如果是这种情况，我强烈建议阅读Spring的依赖注入。

现在您需要连接EntityManager。这可以通过两种方式完成。

第一种方法要求您在XML中将其指定为bean。如果您已经这样做，只需注释您的EntityManager字段。

@Autowired
protected EntityManager entityManager;

或者，由于您在XML中指定了一个DataSource，因此您应该能够使用@PersistenceContext引用它并向其传递ID值。

@PersistenceContext(name="DataSource")
protected EntityManager entityManager;

我从未真正使用过后一种方法，但我已经看到过这样做了。我通常在XML中指定一个EntityManager bean并使用@Autowired，如前一种方法所述。

访问EntityManager时出现NullPointerException

1 个答案: