Spring JPA - org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean无法强制转换为javax.persistence.EntityManagerFactory

Question

目前我试图让JPA示例使用spring boot

(http://spring.io/guides/tutorials/data/3/).

当我使用示例中的代码时:

@Bean
public DataSource dataSource() throws SQLException {

EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder();
return builder.setType(EmbeddedDatabaseType.H2).build();
}

@Bean
public EntityManagerFactory entityManagerFactory() throws SQLException {

HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
vendorAdapter.setGenerateDdl(true);

LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setJpaVendorAdapter(vendorAdapter);
factory.setPackagesToScan("com.yummynoodlebar.persistence.domain");
factory.setDataSource(dataSource());
factory.afterPropertiesSet();

return factory.getObject();
}

@Bean
public EntityManager entityManager(EntityManagerFactory entityManagerFactory) {
return entityManagerFactory.createEntityManager();
}

@Bean
public PlatformTransactionManager transactionManager() throws SQLException {

JpaTransactionManager txManager = new JpaTransactionManager();
txManager.setEntityManagerFactory(entityManagerFactory());
return txManager;
}

@Bean
public HibernateExceptionTranslator hibernateExceptionTranslator() {
return new HibernateExceptionTranslator();
}

我总是得到异常"引起:java.lang.ClassCastException:org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean $$ EnhancerBySpringCGLIB $$ 3cbaf28d无法转换为javax.persistence.EntityManagerFactory".

我在自己的数据源中使用此示例:

@Bean
    public DataSource dataSource() {
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUsername("user");
        dataSource.setMaxTotal(5);
        dataSource.setInitialSize(2);
        dataSource.setPassword("pw");
        dataSource.setUrl("jdbc:mysql://localhost/data");
        return dataSource;
    }

当我正在处理某些事情时,一切正常:

我将"EntityManagerFactory" - 方法更改为:

public LocalContainerEntityManagerFactoryBean entityManagerFactory() ...

和transactionManager方法:

public PlatformTransactionManager transactionManager(
        EntityManagerFactory emf) throws SQLException {

并通过方法变量"emf"直接设置EntityManagerFactory.

这是为什么？

有人可以向我解释为什么教程中的示例不起作用？我正在为这个项目使用mysql驱动程序.

谢谢!

问候

Answer 1

这可能有所帮助:

@Bean
    public PlatformTransactionManager transactionManager(final EntityManagerFactory emf) {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);
        transactionManager.setDataSource(dataSource());
        transactionManager.setJpaDialect(jpaDialect());
        return transactionManager;
    }

Answer 2

尝试在 XML 配置中创建 TransactionManager，如下所示：

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

并使用注释导入：

@ImportResource("classpath*:/config.xml")