# 79.12 配置JPA使用的组件

如果想配置一个JPA使用的组件，你需要确保该组件在JPA之前初始化。组件如果是Spring Boot自动配置的，Spring Boot会为你处理。例如，Flyway是自动配置的，Hibernate依赖于Flyway，这样Hibernate有机会在使用数据库前对其进行初始化。

如果自己配置组件，你可以使用`EntityManagerFactoryDependsOnPostProcessor`子类设置必要的依赖，例如，如果你正使用Hibernate搜索，并将Elasticsearch作为它的索引管理器，这样任何`EntityManagerFactory` beans必须设置为依赖`elasticsearchClient` bean：

```java
/**
 * {@link EntityManagerFactoryDependsOnPostProcessor} that ensures that
 * {@link EntityManagerFactory} beans depend on the {@code elasticsearchClient} bean.
 */
@Configuration
static class ElasticsearchJpaDependencyConfiguration
        extends EntityManagerFactoryDependsOnPostProcessor {

    ElasticsearchJpaDependencyConfiguration() {
        super("elasticsearchClient");
    }

}
```


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