無法配置JPA項目

我試圖配置一個簡單的JPA項目，我很困難。無法配置JPA項目

我有一個工作dataSource（Oracle數據庫）與表SIMPLE其中包含ID(NUMBER)和WORD(VARCHAR2)。

只有當我在SimpleObject類中添加@GeneratedValue註釋時，我纔會收到異常。如果沒有註釋，我可以從數據庫表中獲取數據，但我無法保存新記錄。

我試過的GeneratedValue策略更改爲

@GeneratedValue(strategy=GenerationType.SEQUENCE)

和我在我的DB序列simple_seq所以我試着這樣做：

@Id 
@GeneratedValue(generator="mySeq") 
@SequenceGenerator(name="mySeq",sequenceName="SIMPLE_SEQ") 
private long id;

我不斷收到同樣的異常..

這裏是我的課程：

SimpleObject cla SS從表映射數據

package lt.tomas.proSpring3; 

import javax.persistence.*; 

@Entity 
@Table(name = "simple") 
@NamedQueries({ 
    @NamedQuery(name="SimpleObject.findAll",query = "SELECT c FROM SimpleObject c"), 
@NamedQuery(name="SimpleObject.findById" , query = "SELECT c FROM SimpleObject c where c.id = :id") 
}) 
public class SimpleObject { 


    private Long id; 
    private String word; 

    @Id 
    @GeneratedValue 
    @Column(name = "ID") 
    public long getId() { 
     return id; 
    } 

    public void setId(Long id) { 
     this.id = id; 
    } 


    @Column(name = "WORD") 
    public String getWord(){ 
     return word; 
    } 

    public void setWord(String word){ 
     this.word = word; 
    } 

    public String toString(){ 
     return "ID: " + id + " WORD: " + word ; 
    } 


}

上simpleObject

package lt.tomas.proSpring3; 

import java.util.List; 

import javax.persistence.*; 

import org.springframework.stereotype.Repository; 
import org.springframework.stereotype.Service; 
import org.springframework.transaction.annotation.Transactional; 


@Service("jpaSimpleService") 
@Repository 
@Transactional 
public class SimpleObjectImpl{ 

    @PersistenceContext(unitName="emf") 
    private EntityManager em; 

    @Transactional(readOnly=true) 
    public List<SimpleObject> findAll(){ 
     return em.createNamedQuery("SimpleObject.findAll", SimpleObject.class).getResultList(); 
    } 

    @Transactional(readOnly=true) 
    public SimpleObject findById(Long id){ 
     TypedQuery<SimpleObject> tq = em.createNamedQuery("SimpleObject.findById", SimpleObject.class); 
     tq.setParameter("ID", id); 
     return tq.getSingleResult(); 
    } 

    public void save(SimpleObject s) { 
     em.persist(s); 
    } 

    public void update(SimpleObject s){ 
     em.merge(s); 
    } 

    public void Delete(SimpleObject c) { 
     // TODO Auto-generated method stub 

    } 

}

，以測試它的所有

package lt.tomas.proSpring3; 

import java.util.List; 

import org.springframework.context.support.GenericXmlApplicationContext; 

public class JPATest { 

    public static void main(String[] args) { 
     GenericXmlApplicationContext ctx = new GenericXmlApplicationContext(); 
     ctx.load("app-context.xml"); 
     ctx.refresh(); 

     SimpleObjectImpl si = ctx.getBean("jpaSimpleService", SimpleObjectImpl.class); 
     List<SimpleObject> objects = si.findAll(); 
     for(SimpleObject obj : objects){ 
      System.out.println(obj); 
     } 
    } 
}

語境config.xml文件的類數據執行的操作

SimpleObjectImpl類

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" 
    xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:tx="http://www.springframework.org/schema/tx" 
    xsi:schemaLocation="http://www.springframework.org/schema/jdbc 
http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd 
http://www.springframework.org/schema/beans 
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd 
http://www.springframework.org/schema/tx 
http://www.springframework.org/schema/tx/spring-tx-3.1.xsd 
http://www.springframework.org/schema/context 
http://www.springframework.org/schema/context/spring-context-3.1.xsd"> 


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

    <context:property-placeholder location="jdbc.properties"/> 

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> 
     <property name="entityManagerFactory" ref="emf" /> 
    </bean> 

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

    <bean id="emf" 
     class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> 
     <property name="dataSource" ref="dataSource" /> 
     <property name="jpaVendorAdapter"> 
      <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" /> 
     </property> 
     <property name="packagesToScan" value="lt.tomas.proSpring3" /> 
     <property name="jpaProperties"> 
      <props> 
       <prop key="hibernate.dialect"> 
        org.hibernate.dialect.Oracle10gDialect 
       </prop> 
       <prop key="hibernate.max_fetch_depth">3</prop> 
       <prop key="hibernate.jdbc.fetch_size">50</prop> 
       <prop key="hibernate.jdbc.batch_size">10</prop> 
       <prop key="hibernate.show_sql">true</prop> 
      </props> 
     </property> 
    </bean> 

    <context:annotation-config /> 

    <context:component-scan base-package="lt.tomas.proSpring3"/> 
</beans>

和例外

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager' defined in class path resource [app-context.xml]: Cannot resolve reference to bean 'emf' while setting bean property 'entityManagerFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'emf' defined in class path resource [app-context.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build EntityManagerFactory 
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328) 
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:106) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1360) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1118) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585) 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464) 
    at lt.tomas.proSpring3.JPATest.main(JPATest.java:12) 
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'emf' defined in class path resource [app-context.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build EntityManagerFactory 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1455) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) 
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:322) 
    ... 13 more 
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build EntityManagerFactory 
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:915) 
    at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:74) 
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:257) 
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:310) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1514) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1452) 
    ... 20 more 
Caused by: org.hibernate.PropertyAccessException: Exception occurred inside getter of lt.tomas.proSpring3.SimpleObject.id 
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:175) 
    at org.hibernate.engine.UnsavedValueFactory.getUnsavedIdentifierValue(UnsavedValueFactory.java:67) 
    at org.hibernate.tuple.PropertyFactory.buildIdentifierProperty(PropertyFactory.java:67) 
    at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:135) 
    at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:485) 
    at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:133) 
    at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:84) 
    at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:286) 
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1872) 
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:906) 
    ... 25 more 
Caused by: java.lang.reflect.InvocationTargetException 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    at java.lang.reflect.Method.invoke(Unknown Source) 
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:172) 
    ... 34 more 
Caused by: java.lang.NullPointerException 
    at lt.tomas.proSpring3.SimpleObject.getId(SimpleObject.java:21) 
    ... 39 more

你能告訴我爲什麼這個異常出現了，我做錯了嗎？先謝謝你。

來源

2013-08-03 Tomas

請編輯您的問題以顯示**相關**信息，否則是TL; DR問題。 –

這是你的問題：

private Long id;

id是Long，這是null因爲它不是實例化。

當JPA通過getId()方法訪問它，它期望一個long和不Long，所以訪問器試圖將null轉換爲原始值，因此具有NullPointerException。

最佳的解決方案是：1）更改id是一個long並添加@NotNull註釋到getId()方法。

我希望這會有所幫助。

來源

2013-08-03 22:06:36

你再次救了我，它工作，謝謝！ – Tomas

不客氣。不要忘記接受點滴分數下方複選標記的答案。 –

無法配置JPA項目

回答

相關問題