如何在没有 persistence.xml 的情况下配置 Spring？

Question

我正在尝试设置 spring xml 配置，而不必再创建一个 persistence.xml。但是我经常遇到以下异常，即使我将数据库属性包含在 spring.xml

    Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in file [C:\Users\me\workspace\app\src\main\webapp\WEB-INF\applicationContext.xml]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: No persistence units parsed from {classpath*:META-INF/persistence.xml}

spring.xml：

  <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${jdbc.driverClassName}" />
    <property name="url" value="${jdbc.url}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
  </bean>

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
     <property name="jpaProperties">
         <props>
            <prop key="hibernate.dialect">${hibernate.dialect}</prop>
            <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>
            <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
            <prop key="hibernate.format_sql">${hibernate.format_sql}</prop>
         </props>
      </property>
    </bean>

我在这里错过了什么？

Answer 1

来自弹簧指南Accessing Data with JPA

@Configuration
@EnableJpaRepositories
public class Application {

    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder().setType(H2).build();
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter) {
        LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
        lef.setDataSource(dataSource);
        lef.setJpaVendorAdapter(jpaVendorAdapter);
        lef.setPackagesToScan("hello");
        return lef;
    }

    @Bean
    public JpaVendorAdapter jpaVendorAdapter() {
        HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
        hibernateJpaVendorAdapter.setShowSql(false);
        hibernateJpaVendorAdapter.setGenerateDdl(true);
        hibernateJpaVendorAdapter.setDatabase(Database.H2);
        return hibernateJpaVendorAdapter;
    }

春季启动

使用启用 Spring Boot 的应用程序会更容易：

示例application.yaml

spring:
    datasource:
        url: jdbc:h2:mem:test
        username: sa
        password: sa
        driver-class-name: org.h2.Driver
    jpa:
        database: H2
        show-sql: false
        hibernate:
            format_sql: true
            ddl-auto: auto

Answer 2

在 entityManagerFactory bean 定义中指定“packagesToScan”和“persistenceUnitName”属性。

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

        <property name="persistenceUnitName" value="myPersistenceUnit" />
        <property name="packagesToScan" >
            <list>
                <value>org.mypackage.*.model</value>
            </list>
        </property>

        <property name="jpaProperties">
            <props>
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>
                <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>
                <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
                <prop key="hibernate.format_sql">${hibernate.format_sql}</prop>
            </props>
        </property>
    </bean>

请注意，这是针对 Spring 版本 > 3.1

Answer 3

MariuszS 的回答很好，只是 entityManagerFactory 方法应该返回 EntityManagerFactory。为此，可以这样写：

@Bean
public EntityManagerFactory entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter) {
    LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
    lef.setDataSource(dataSource);
    lef.setJpaVendorAdapter(jpaVendorAdapter);
    lef.setPackagesToScan("hello");
    return lef.object();
}

对于未来的观众：以下代码有效：

@Bean (name = "entityManagerFactory")
public EntityManagerFactory entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter)
{
    LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
    lef.setDataSource(dataSource);
    lef.setJpaVendorAdapter(jpaVendorAdapter);
    lef.setPackagesToScan("*.models*");
    lef.afterPropertiesSet(); // It will initialize EntityManagerFactory object otherwise below will return null
    return lef.getObject();
}

Answer 4

假设你有一个PersistenceProvider 实现（例如org.hibernate.jpa.HibernatePersistenceProvider），你可以使用PersistenceProvider#createContainerEntityManagerFactory(PersistenceUnitInfo info, Map map) 方法来引导一个EntityManagerFactory 而不需要persistence.xml。

但是，您必须实现 PersistenceUnitInfo 接口很烦人，因此您最好使用 Spring 或 Hibernate，它们都支持在没有 persistence.xml 文件的情况下引导 JPA。

this.nativeEntityManagerFactory = provider.createContainerEntityManagerFactory(
    this.persistenceUnitInfo, 
    getJpaPropertyMap()
);

PersistenceUnitInfo 由 Spring 特定的 MutablePersistenceUnitInfo 类实现。