我試圖實現Spring MVC 3 + EclipseLink的JPA 2 當我打電話saveUser例如它返回EntityManager的是DAO類空
NullPointerException異常的,但EntityManager是 空
:
public class UserDAO {
@PersistenceContext
private EntityManager em;
public void setEntityManager(EntityManager em) {
this.em = em;
}
@Transactional
public User saveUser(User user){
return em.merge(user);
}
我的配置是:
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
<property name="dataSource" ref="dataSource"></property>
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="persistenceUnitName" value="application" />
<property name="jpaVendorAdapter">
<bean
class="org.springframework.orm.jpa.vendor.EclipseLinkJpaVendorAdapter">
<property name="showSql" value="true" />
<property name="databasePlatform" value="org.eclipse.persistence.platform.database.MySQLPlatform" />
<property name="generateDdl" value="false" />
</bean>
</property>
<property name="loadTimeWeaver">
<bean
class="org.springframework.instrument.classloading.SimpleLoadTimeWeaver" />
</property>
</bean>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="username" value=".." />
<property name="password" value=".." />
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url"
value="jdbc:mysql://..." />
</bean>
也有
<context:component-scan base-package="com.elasticbeanstalk.mypackage" />
<context:annotation-config />
Tomcat啓動時它初始化JPA。爲什麼我會看到NPE?我能錯過什麼嗎?
您可以將服務類的代碼發佈到您的DAO正在使用的位置嗎? – gouki
不,我沒有任何服務級別。剛剛從Controller中試過以下UserDAO userDAO = new UserDAO();用戶用戶=新用戶(); user.setName( 「名稱」); userDAO.save(用戶);我必須把東西放在中間嗎? – chro