版本

springboot 2.6.x

现象

jpa配置多数据源后启动报错

Consider defining a bean named ‘entityManagerFactory’

解决

方法1：将其中一个datasource添加@Primary注解
方法2：自行定义entityManagerFactory

private static JpaVendorAdapter jpaVendorAdapter(JpaProperties properties) {
    AbstractJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
    adapter.setShowSql(properties.isShowSql());
    if (properties.getDatabase() != null) {
        adapter.setDatabase(properties.getDatabase());
    }
    if (properties.getDatabasePlatform() != null) {
        adapter.setDatabasePlatform(properties.getDatabasePlatform());
    }
    adapter.setGenerateDdl(properties.isGenerateDdl());
    return adapter;
}
@Bean
public EntityManagerFactoryBuilder entityManagerFactoryBuilder(
        ObjectProvider<PersistenceUnitManager> persistenceUnitManager,
        ObjectProvider<EntityManagerFactoryBuilderCustomizer> customizers
) {
    EntityManagerFactoryBuilder builder = new EntityManagerFactoryBuilder(
            jpaVendorAdapter(jpaProperties()),
            this.jpaProperties().getProperties(),
            (PersistenceUnitManager) persistenceUnitManager.getIfAvailable()
    );
    customizers.orderedStream().forEach((customizer) -> {
        customizer.customize(builder);
    });
    return builder;
}

源码分析

springboot jpa自动配置需要存在单一候选DataSource时才会生效
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration

@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(HibernateProperties.class)
@ConditionalOnSingleCandidate(DataSource.class)
class HibernateJpaConfiguration extends JpaBaseConfiguration {...}